bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for melatonin synthesis in rodent Harderian gland: A dynamic in vitro study
Authors: Djeridane Yasmina , Vivien‐Roels Berthe , Simonneaux Valérie , Miguez Jesus M. , Pévet Paul
Published: February 2007

ABSTRACT: Melatonin content and release from Harderian glands (HGs) has been measured by an in vitro perifusion technique in three rodent species: Wistar rat, Syrian hamster, and Siberian hamster. Melatonin immunoreactive concentrations in HGs of animals killed at 10.00 hr were 0.31 ± 0.031 pg/mg gland in male Wistar rat, 0.54 ± 0.026 pg/mg gland in male Siberian hamster, 0.17 ± 0.070 and 0.20 ± 0.059 pg/mg gland in male and female Syrian hamster, respectively. In all species examined, isolated HGs perifused for 9–15 hr released melatonin but did not stabilize their melatonin release rate. No sex‐related difference could be noted in the HG melatonin release rate. The total amount of melatonin released over a 15 hr long perifusion was about 0.075 ± 0.004 ng/15 h/mg gland and 0.063 ± 0.010 ng/15 hr/mg gland in male and female Wistar rat, respectively; 0.155 ± 0.019 ng/15 hr/mg gland and 0.141 ± 0.006 ng/15 hr/mg gland in male and female Siberian hamster, respectively; 0.035 ± 0.003 ng/15 hr/mg gland and 0.045 ± 0.004 ng/15 hr/mg gland in male and female Syrian hamster, respectively. This amount, which is higher than the tissue levels, demonstrates the de novo melatonin synthesis. This is confirmed by the fact that infusion of the indoleamine precursor, tryptophan (TRP), stimulated melatonin secretion from HGs. The melatonin release is increased by 2.5‐fold in male and female Wistar rat, 1.5‐fold in male and female Siberian hamster, and 2.0‐ and 3.0‐fold in male and female Syrian hamster, respectively. Treatment with a TRP hydroxylase inhibitor, para‐chlorophenylalanine, reduced basal melatonin release and inhibited the TRP‐induced melatonin stimulation. Kinetics and amounts of melatonin released were not affected by pinealectomy, ruling out a possible plasmatic origin of the HG melatonin. Isoproterenol, a β‐adrenergic agonist, and dibutyryl cyclic AMP, a cyclic AMP analogue, failed to stimulate HG melatonin secretion. In conclusion, these results confirm the presence of melatonin in the HGs and demonstrate that melatonin is synthesized in and released from isolated rodent HGs.
Altered circadian melatonin secretion patterns in relation to sleep in patients with chronic sleep‐wake rhythm disorders
Authors: Rodenbeck Andrea , Huether Gerald , Rüther Eckart , Hajak Goran
Published: February 2007

Rodenbeck A, Huether G, Rüther E, Hajak G. Altered circadian melatonin secretion patterns in relation to sleep in patients with chronic sleep‐wake rhythm disorders. J. Pineal Res. 1998; 25:201–210. © Munksgaard, Copenhagen

Human well‐being depends on the entrainment of endogenous circadian rhythms of biological functions and the sleep‐wake rhythm. Although the incidence of otherwise healthy subjects with chronically altered sleep‐wake rhythms is rather low, the investigation of these patients provides new sights into circadian entrainment mechanisms. We therefore examined the circadian rhythm of circulating melatonin and the sleep‐wake rhythm in five patients with chronic sleep‐wake rhythm disorders and ten age‐matched healthy controls. All patients showed altered circadian melatonin rhythm parameters in relation to their sleep‐wake cycle compared to age‐matched controls. These alterations were random, i.e., independent of the type, the duration, and the age of onset of the disorder. The melatonin onset to sleep onset interval varied between the patients and the melatonin acrophase to sleep offset interval was prolonged in four patients. These findings indicate individual phase relations between the circadian melatonin rhythm and the sleep‐wake cycle in patients with chronic sleep‐wake rhythm disorders. Since the prolonged melatonin acrophase to sleep offset interval was the most consistent finding independent of aetiological origins, this abnormality may be one possible maintaining factor in chronic sleep‐wake rhythm disorders due to reduced phase‐resetting properties of the circadian pacemaker. Furthermore, rather low circadian melatonin amplitudes and a subsensitivity to daylight may maintain the disorder in at least some patients.
Effect of continuous melatonin infusions on steady‐state plasma melatonin levels in rats under near physiological conditions
Authors: Huether G. , Messner M. , Rodenbeck A. , Hardeland R.
Published: February 2007

Abstract: It was the aim of this study to measure the actual amount of melatonin required for elevating the circulating hormone from low daytime levels to the 10‐fold higher nocturnal steady‐state concentrations in rats. For this purpose, escalating doses of melatonin were continuously infused into the right jugular vein and blood samples were repeatedly drawn from the left jugular vein for a period of 2 hr in freely moving catheterized rats. In order to achieve an about 10‐fold elevation of the plasma melatonin concentration, 500 ng melatonin/hr had to be infused, i.e., about 300 times the normal nocturnal melatonin content of the pineal. Infusions of up to 61 ng melatonin/hr (equivalent to the melatonin content of 40 pineals at darkness) failed to cause a significant rise of the low daytime steady‐state concentrations in the blood. If the dose of 500 ng melatonin/h was infused at night, a less‐pronounced rise of the blood levels was observed, as compared to that caused by the infusion of the same dose during daytime. No differences were found in the rate of metabolism between daytime and nighttime. The results of this study indicate 1) that the low basal concentrations of melatonin in the blood are not affected by an increased melatonin supply up to a certain critical threshold, 2) that the rat pineal gland would have to release all its melatonin content almost every 10 sec in order to sustain the elevated steady‐state level of melatonin in the circulation during the dark period, and 3) that significant day/night differences exist in the disposition of circulating melatonin if administered in near physiological amounts and under near physiological conditions.
Circadian secretion patterns of melatonin after major surgery
Authors: Nishimura Shinya , Fujino Yuji , Shimaoka Motomu , Hagihira Satoshi , Taenaka Nobuyuki , Yoshiya Ikuto
Published: February 2007

Abstract: Biorhythms, such as regular variation in core body temperature and the pattern of the secretion of melatonin, are thought to be mediated by the same biological clock. Core body temperature is affected by the inflammatory response to major surgery. Apart from the well‐known inhibitory effect of bright light on its secretion, melatonin is an exceedingly good marker of one of the central generating systems of circadian rhythms. We sequentially measured the plasma melatonin concentration pattern in patients who had undergone esophagectomy with thoracotomy to elucidate the circadian rhythm after major surgery. From seven patients who had received esophagectomy with thoracotomy for esophageal cancer, plasma concentrations of melatonin were measured using an RIA method. Blood samples were collected via each patient's arterial line at 00.00, 02.00, 04.00, 06.00, 08.00, 12.00, 16.00, 20.00, and 24.00 hr on the first postoperative day for six of the patients, and, for one patient, every 2 hr until the third postoperative day and every 4 hr thereafter until the sixth postoperative day. Four patients out of seven had melatonin concentrations of over 30 pg/ml (mean 34 pg/ml) at 24.00 hr on the first postoperative day. Five patients showed circadian secretion patterns of melatonin during the first postoperative day. One patient whose melatonin concentrations were measured consecutively for 6 days showed a regular circadian secretion pattern through the 6 days of the study. Even the stress caused by extremely invasive surgery did not significantly disturb the melatonin secretion pattern.
Protective effect of melatonin on cellular energy depletion mediated by peroxynitrite and poly (ADP‐ribose) synthetase activation in a non‐septic shock model induced by zymosan in the rat
Authors: Cuzzocrea Salvatore , Costantino Giuseppina , Caputi Achille P.
Published: February 2007

Abstract: DNA single‐strand breakage and activation of the nuclear enzyme poly (ADP‐ribose) synthetase (PARS) triggers an energy‐consuming, inefficient repair cycle, which contributes to peroxynitrite‐induced cellular injury. Recently it was proposed that zymosan, a non‐bacterial agent, causes cellular injury by inducing the production of peroxynitrite and consequent PARS activation. Here we investigated whether in vivo melatonin treatment inhibits cellular injury induced by peroxynitrite production and PARS activation in macrophages collected from rats subjected to zymosan‐induced shock. Macrophages harvested from the peritoneal cavity exhibited a significant production of peroxynitrite, as measured by the oxidation of the fluorescent dye dihydrorhodamine 123. Furthermore, zymosan‐induced shock caused a suppression of macrophage mitochondrial respiration, DNA strand breakage, activation of PARS and reduction of cellular levels of NAD+. In vivo treatment with melatonin (25 and 50 mg/kg, intraperitoneally, 1 hr after zymosan injection) significantly reduced in dose‐dependent manner peroxynitrite formation and prevented the appearance of DNA damage, the decrease in mitochondrial respiration, the loss of cellular levels of NAD+, and the PARS activation. Our study supports the view that the antioxidant and antiinflammatory effect of melatonin is also correlated with the inhibition of peroxynitrite production and PARS activation. In conclusion, melatonin may be a novel pharmacological approach to prevent cell injury in inflammation.
Effects of melatonin on macrophages/microglia in postnatal rat brain
Authors: Kaur C. , Ling E. A.
Published: February 2007

Abstract: The present study examined the response of macrophages/microglia to multiple injections of melatonin in the pineal gland and different regions of the brain. The macrophages/microgIia showed a significant increase in cell numbers and upregulation of complement type 3 receptors (CR3), major histocompatibility complex class I (MHC I) and class II (MHC II) antigens, and antigens of monocyte/macrophage lineage, as detected by the antibodies OX‐42, OX‐18, OX‐6, and EDJ, respectively. The upregulation of the above antigens was observed in I‐d‐old rats given daily injections of melatonin and killed at 7–11 d of age; no noticeable change was observed at earlier time intervals. The macrophages/microglia expressing the above antigens appeared round and showed a vacuolated cytoplasm compared with ramified cells in the control rats. Upregulation of CD4 antigens as detected with the antibody W3/25 was also observed in macrophages/microglia in the corpus callosuni and epiplexus cells in the lateral ventricles, but not in the pineal gland and the cerebral cortex in the same age group. In rats killed between 2 and 5 d, and at 14 d of age after melatonin treatment, the immunoreactivities of macrophages/microglia with the above mentioned antibodies were comparable to cells in the control rats. Immunoreactive cells were not detected in any of the age groups in melatonin‐treated or control rats with the antibodies W3/13 and OX‐33, which are markers for T and B lymphocytes. It is concluded that CR3 receptors, MHC antigens, and CD4 antigens on macrophages/microglia are upregulated following melatonin administration. On the other hand, once the melatonin treatment is discontinued the expression of the various antigens/receptors returns to normal levels, suggesting that increased immune potentiality and its maintenance in these cells require the continuous action of the drug.
Effect of melatonin treatment on 24‐hour rhythms of serum ACTH, growth hormone, prolactin, luteinizing hormone and insulin in rats injected with Freund's adjuvant
Authors: Esquifino Ana I. , Castrillón Patricia , García‐Bonacho Manuel , Vara Elena , Cardinali Daniel P.
Published: February 2007

Abstract: The effect of melatonin injection on Freund's adjuvant‐induced changes in levels and 24‐hr rhythms of circulating ACTH, growth hormone (GH), prolactin (PRL), luteinizing hormone (LH), and insulin was assessed in rats. Animals received subcutaneous (s. c.) injections of melatonin (30 ug) or vehicle, 1 hr before lights off for 12 days. Ten days after melatonin treatment, they were injected with Freund's complete adjuvant or its vehicle s. c., and after 3 days, rats were killed at six different time intervals throughout a 24‐hr cycle to measure the different hormones by radioimmunoassay (RIA). Following Freund's adjuvant injection, an increase in serum ACTH, with maintenance of ACTH diurnal rhythm was found. Acrophases of the ACTH rhythm varied from 13: 39 to 17:12 hr and the amplitude of rhythm was augmented after immunization. In immunized rats, melatonin treatment increased the amplitude of serum ACTH rhythm. For GH, a depressive effect of immunization on circulating levels, together with absence of diurnal rhythmicity were found. Immunization augmented circulating PRL, while conserving its diurnal rhythmicity. Melatonin‐injected rats showed significant diurnal variations of serum PRL after immunization only. Acrophases of the serum PRL rhythm varied from 19: 37 to 22:04 hr. Immunization decreased circulating LH and suppressed its 24‐hr rhythmicity pattern. The effect of immunization on LH was counteracted by melatonin injection. Acrophases of serum LH rhythm varied from 00:44 to 03:53 hr. Significant effects of immunization and time of day on circulating insulin were detected; immunization increased serum insulin levels with a shift in acrophase from early afternoon to midnight. The data indicate that several early changes in levels and 24‐hr rhythms of circulating ACTH, PRL, and LH in Freund's adjuvant‐injected rats were sensitive to treatment with pharmacological amounts of melatonin.
Regulation of the expression of serotonin N‐acetyltransferase gene in Japanese quail (Coturnix japonica): I. Rhythmic pattern and effect of light
Authors: Kato Hisanori , Fu Zhengwei , Kotera Naoko , Sugahara Kunio , Kubo Tatsuo
Published: February 2007

Abstract: Serotonin N‐acetyltransferase [arylalkylamine N‐acetyltransferase (AANAT); EC2.3.1.87] is the rate‐limiting enzyme in melatonin synthesis, and its activity exhibits a diurnal rhythm similar to that of the melatonin content in the pineal gland and retina of Japanese quail. Studies were conducted to characterize the Japanese quail AANAT cDNA, and to evaluate the expression of AANAT mRNA in the pineal gland, the retina, and other peripheral tissues. The nucleic acid sequence of a 400 bp cDNA clone obtained by RT‐PCR manifested 78 and 95% homology compared to the rat and chicken AANAT cDNA, respectively, while the deduced amino acid sequence homology was 82 and 99%, respectively. AANAT mRNA content in a single pineal gland or an aliquot of eye lysate was measured by a micro‐lysate protection assay. The expression of AANAT mRNA in the pineal gland and the retina exhibited circadian rhythm with peak levels at night. AANAT mRNA was also detected in the testis, but did not display a rhythmic change over a 24 hr period. AANAT mRNA was not detected in other tissues studied. Darkness during the day did not increase the pineal AANAT mRNA levels. However, unexpected light‐exposure for 2 hr just after lights‐off blocked the increase in AANAT mRNA, and at midnight remarkably decreased AANAT mRNA by 50%
Regulation of the expression of serotonin N‐acetyltransferase gene in Japanese quail (Coturnix japonica): II. Effect of vitamin A deficiency
Authors: Fu Zhengwei , Kato Hisanori , Kotera Naoko , Sugahara Kunio , Kubo Tatsuo
Published: February 2007

Abstract: Levels of serotonin N‐acetyltransferase [arylalkylamine N‐acetyltransferase (AANAT): EC2.3.1.87] mRNA, AANAT activity, and melatonin display a rhythmic pattern in both the pineal gland and the retina. It has been shown that vitamin A is required to maintain the rhythm of melatonin synthesis in the pineal gland of Japanese quail. To understand the mechanism underlying the direct relationship among these factors, we developed an assay system sensitive enough to determine AANAT mRNA, AANAT activity, and melatonin content from a single pineal gland of Japanese quail. Positive direct relationships were found among these three parameters. We next deprived Japanese quail of vitamin A by feeding them a vitamin A‐free diet supplemented with retinoic acid, and examined the effects of vitamin A deficiency on the expression of AANAT mRNA in the pineal gland and the retina. Vitamin A deficiency reduced both the expression of AANAT mRNA and melatonin content in the pineal gland. Retinal AANAT mRNA rhythm disappeared in vitamin A‐deficient quails. Moreover, the responsiveness of the pineal gland and the retina to light was reduced by vitamin A deficiency when compared with the control group.
Melatonin stimulates proliferation and type I collagen synthesis in human bone cells in vitro
Authors: Nakade Osamu , Koyama Hiroki , Ariji Hirohiko , Yajima Akihiro , Kaku Tohru
Published: February 2007

Abstract: The pineal secretory product melatonin reportedly regulates release of growth hormone in humans and prevents phototherapy‐induced hypocalcemia in newborn rats, suggesting that melatonin affects bone metabolism. Little is known about the effects of melatonin on bone in vitro or in vivo. The present study was undertaken to examine whether melatonin acts directly on normal human bone cells (HOB‐M cells) and human osteoblastic cell line (SV‐HFO cells) to affect osteogenic action in vitro. The effect of melatonin on bone cell proliferation was determined using the 2, 3‐bis[2‐methoxy‐4‐nitro‐5‐sulfophenyl]‐2H‐tetrazolium‐5‐carboxanilide (XTT) assay after a 24 hr incubation with melatonin. Melatonin significantly and dose‐dependently increased the proliferation in HOB‐M cells and SV‐HFO cells by 215 ± 22.1%, and 193 ± 6.4%, respectively, with a maximal effect at a concentration of 50 μM. To evaluate the effect of melatonin on bone cell differentiation, alkaline phosphatase (ALP) activity, osteocalcin secretion and procollagen type I c‐peptide (PICP) production (a measure of type I collagen synthesis) were measured after a 48 hr treatment. While melatonin at micromolar concentrations did not significantly affect either the ALP activity or the osteocalcin secretion, it significantly and dose‐dependently increased the PICP production in HOB‐M cells and SV‐HFO cells by 983 ± 42.2%, and 139 ± 4.2%, respectively, with the maximal stimulatory doses between 50 and 100 μM. These results provide new evidence that melatonin stimulates the proliferation and type I collagen synthesis in human bone cells in vitro, suggesting that melatonin may act to stimulate bone formation.
A method of achieving physiological plasma levels of melatonin in the chicken by oral administration
Authors: Neddegaard Flemming , Kennaway David J.
Published: February 2007

Abstract: In avian species it has been difficult to elucidate the precise role of melatonin in the control of reproductive cycles. We have investigated ways of administering melatonin to immature chickens and laying hens to achieve physiological levels and patterns in blood simulating either short or long photoperiods. Melatonin was administered orally using different doses and various ways of applying melatonin to the feed. For subcutaneous injections, melatonin was suspended in propylene glycol or grape seed oil. Melatonin always appeared in the first blood samples taken within an hour of administration. When melatonin was absorbed into feed pellets or whole wheat, a high initial plasma concentration was reached. followed by a rapid decrease over the ensuing 2–3 hr, but was still detectable as long as 24 hr after administration. For example, doses of 300 μg/kg produced 15 nM, which is more than ten times higher than the nocturnal peak concentration. When melatonin was absorbed into cracked wheat grains that were subsequently washed with ethanol, the initial transitory peak was eliminated, levels in plasma were sustained for at least 12 hr in the normal nocturnal range (750 pM), and no melatonin (< 60 pM) was present 18 hr later. When injected (2 μg/bird), concentrations peaked (610 pM) within 30 min and decreased rapidly over the next 2–3 hr. It was concluded that melatonin‐treated. ethanol‐rinsed cracked wheat grains can be used to experimentally mimic long‐night plasma melatonin patterns. Injections may be useful for mimicking the melatonin patterns of very short nights in chickens experiencing constant light.
The Interaction of Two Tethering Factors, p115 and COG complex, is Required for Golgi Integrity
Authors: Sohda Miwa , Misumi Yoshio , Yoshimura Shin‐ichiro , Nakamura Nobuhiro , Fusano Takami , Ogata Shigenori , Sakisaka Shotaro , Ikehara Yukio
Published: February 2007

The vesicle‐tethering protein p115 functions in endoplasmic reticulum–Golgi trafficking. We explored the function of homologous region 2 (HR2) of the p115 head domain that is highly homologous with the yeast counterpart, Uso1p. By expression of p115 mutants in p115 knockdown (KD) cells, we found that deletion of HR2 caused an irregular assembly of the Golgi, which consisted of a cluster of mini‐stacked Golgi fragments, and gathered around microtubule‐organizing center in a microtubule‐dependent manner. Protein interaction analyses revealed that p115 HR2 interacted with Cog2, a subunit of the conserved oligomeric Golgi (COG) complex that is known another putative cis‐Golgi vesicle‐tethering factor. The interaction between p115 and Cog2 was found to be essential for Golgi ribbon reformation after the disruption of the ribbon by p115 KD or brefeldin A treatment and recovery by re‐expression of p115 or drug wash out, respectively. The interaction occurred only in interphase cells and not in mitotic cells. These results strongly suggested that p115 plays an important role in the biogenesis and maintenance of the Golgi by interacting with the COG complex on the cis‐Golgi in vesicular trafficking.
The Phagosome: Compartment with a License to Kill
Authors: Haas Albert
Published: February 2007

Phagosomes are fascinating subcellular structures. After all, there are only a few compartments that are born before our very eyes and whose development we can follow in a light microscope until their contents disintegrate and are completely absorbed. Yet, some phagosomes are taken advantage of by pathogenic microorganisms, which change their fate. Research into phagosome biogenesis has flourished in recent years – the purpose of this review is to give a glimpse of where this research stands, with emphasis on the cell biology of macrophage phagosomes, on new model organisms for the study of phagosome biogenesis and on intracellular pathogens and their interference with normal phagosome function.
ENGINEERING ANALYSIS OF SOY DOUGH RHEOLOGY IN EXTRUSION
Authors: JAO Y. C. , CHEN A. H. , LEWANDOWSKI D. , IRWIN W. E.
Published: February 2007

Effects of moisture level, temperature and shear rate on the rheological properties of defatted soy dough during extrusion were studied on a Brabender laboratory extruder. Entrance pressure loss through the extruder capillary die as well as viscosity of the cooked and compressed soy dough were expressed as a function of added moisture, shear rate and temperature through multiple regression analysis. Process conditions involved in this study were (a) temperature from 100 to 160°C; (b) added moisture from 22 to 32% and (c) shear rate from 50 to 10,500 sec−1. Data were collected at steady state. It was found that in the shear rate range of 50 to 1,000 sec−1 and temperature range of 100 to 160°C the viscosity of the cooked and compressed soy dough with 32%, 25% and 22% added moisture ranged from 10,000 to 500 poise and 20,000 to 200 poise and 20,000 to 1,000 poise respectively.
THE EFFECTS OF DESIGN AND OPERATING CONDITIONS ON PARTICLE MORPHOLOGY FOR SPRAY‐DRIED FOODS
Authors: GREENWALD C. GAIL , KING C. JUDSON
Published: February 2007

An experimental program was carried out in order to provide insight into the effects of the design and operating conditions of spray drying on the morphological behavior of the product. Single streams of uniform‐size drops fell through a column in which air temperature profiles could be monitored and manipulated. Scanning electron microscopy and optical microscopy were used to measure shrinkage (or expansion) and to observe physical characteristics. The effects of varying the type of feed, the feed concentration, initial drop size, and air temperature history were investigated. Results are compared with previous investigations related to bulk density.
EFFECTS OF RECOVERY METHODS ON THE FUNCTIONALITY OF PROTEIN CONCENTRATES FROM FOOD PROCESSING WASTES1
Authors: KNORR D.
Published: February 2007

The multiple effects of the method of protein recovery on food protein functionality are presented. The results indicate the influence of method of protein coagulation (heat coagulation versus coagulation at room temperature) and type of coagulant (HCl, FeCl3, Al2(SO4)3, citric acid) on protein solubility, water binding capacity and baking properties. Dehydration conditions such as air inlet/outlet temperature (120‐125/42‐42° C to 190‐195/70‐72°C) or pH of the protein coagulate (pH 4 to 8) as well as methods of dehydration (freeze‐, spray‐, drum‐drying) affected the water binding capacity and protein solubility of plant protein concentrates. Insignificant correlations (P < 0.01) existed between solubility values and water binding capacity data. Marked effects of the interactions between method of dehydration, protein source or dehydration temperature and pH of the coagulate on protein functionality were found.

Based on the data presented it is proposed to develop processes for the production of protein concentrates with “tailored” functionality by selecting specific protein recovery processes and by mixing differently processed protein concentrates.
A REVIEW ON PREDICTING FREEZING TIMES OF FOODS
Authors: RAMASWAMY H. S. , TUNG M. A.
Published: February 2007

Heat transfer during freezing of a food material involves a complex situation of simultaneous phase transition and changing thermal properties. Models for predicting freezing times range from relatively simple analytical equations based on a number of assumptions and approximations, to the more versatile numerical methods which require the use of a sophisticated computer. The necessity for having a consistent definition for freezing time, the nature of the freezing process, different prediction models and thermo‐physical properties of importance are discussed in view of the mathematics of freezing time computations. In this review, attention has been focused on established analytical models which can be solved without resorting to computer techniques. The review points out the need for further refinement of the existing Plank‐type models to facilitate accurate freezing time estimations under a wide range of practical conditions.
MODELING HEAT AND MASS TRANSFER DURING THE OVEN ROASTING OF MEAT
Authors: SINGH NEERA , AKINS R. G. , ERICKSON L. E.
Published: February 2007

The roasting (baking) of meat involves both heat and mass transfer. A mathematical model which describes the roasting process as it occurs in a conventional oven is presented. Numerical solutions are presented for several different roasting conditions and the results are compared to available experimental results. A significant fraction of the energy required for roasting is associated with the evaporation of water and this needs to be considered in modeling the roasting process. Water losses due to mass transfer from the product depend on oven humidity and temperature. The mathematical model considers the variation of oven humidity with time during roasting. The implicit alternating direction finite difference method is used to obtain the numerical solutions.
HEAT TRANSFER COEFFICIENTS to NEWTONIAN LIQUIDS IN AXIALLY ROTATED CANS
Authors: SOULÉ CARLOS LUCIO , MERSON RICHARD L.
Published: February 2007

Overall heat transfer coefficients to water and silicone fluids in cans rotating in a steam retort were correlated by (Eq. A):

image

where the Reynolds number, pND2/μ, based on the rotational speed of the can, was varied over the range 12 < Re <44,000, the Prandtl number c0μ/k was tested between 2.2 and 2300, the can length to diameter ratio was varied over 1.11 < L/D<1.61, and the ratio of bulk to wall viscosities, μb/μw, was varied between 1.22 and 1.79. All fluid properties were evaluated at the arithmetic average of the initial and final temperatures of the can wall. Data for 106 trials were correlated with a multiple regression correlation coefficient of R’= 0.916. Internal film coefficients were about 7% higher than U values and can be calculated by h = (1.07 ± 0.04) U.
QUANTITATIVE ANALYSIS OF TEXTURE CHANGE IN COD MUSCLE DURING FROZEN STORAGE
Authors: KIM YOON J. , HELDMAN DENNIS R.
Published: February 2007

The textural deterioration of cod muscle during frozen storage was investigated by objective measurement using the Instron Universal Testing Machine. The rates of texture change as a function of storage time revealed that the increased toughness and decreased cohesiveness could be described by a first‐order relationship. Higher storage temperatures resulted in more rapid rates of textural deterioration. Larger activation energy constants for toughness of cod muscle as compared to cohesiveness indicated that toughening was more temperature dependent than cohesiveness. The increased toughness and the decreased cohesiveness of frozen‐stored fish appeared to be related to the protein denaturation of the cod muscle and the loss of water‐holding capacity, respectively.
ACTIVITY COEFFICIENTS of AROMA COMPOUNDS and WATER ACTIVITY IN MODEL SYSTEMS
Authors: VOILLEY A.
Published: February 2007

One aim of this work was to measure the activity of water and aroma compounds in aqueous solutions simultaneously.

The volatilities of aroma substances at infinite dilution in aqueous solutions of polyethylene‐glycols (PEG) were studied. the activity coefficients (γi∞) of volatile compounds were measured by gas stripping (exponential dilution). This dynamic method also allowed the measurement of the water activity of these solutions. the results showed that:

the influence of polyethylene‐glycols on γi∞ depended most strongly on the PEG mass fraction in the solution. the effect of the PEG molecular weight was not significant.

γi∞ increased as molecular weight and length increased for the homologous series of alcohols tested. This can be explained by entropic effects. Probably, the same effect occurs for other homologous series.

γi∞ for 2‐propanone increased as temperature increased. Based on this relation, molar partial excess enthalpies of mixing were calculated for 2‐propanone in an aqueous solution.
EFFECTS of FEED MOISTURE and BARREL TEMPERATURE ON the RHEOLOGICAL PROPERTIES of EXTRUDED COWPEA MEAL1
Authors: KENNEDY M. B. , PHILLIPS R. D. , RAO V. N. M. , CHINNAN M. S.
Published: February 2007

Decorticated cowpea meal was adjusted to 20, 30, and 40% moisture and extruded in a Wayne pilot‐scale extruder at barrel temperatures of 150, 175 and 200°C. the resulting products were subjected to rheological evaluation using the Instron Universal Testing Machine equipped with standard tensile jaws, the Warner‐Bratzler shear device and the Kramer Shear Press. Regression equations relating rheological properties to feed moisture and barrel temperature were computed from the data, and response surfaces were generated from these models. Tensile strength of extrudates was greatest for the dense products produced in the low moisture‐low temperature region and declined at higher moistures and temperatures. Shear strength as determined by either the Warner‐Bratzler or Kramer devices exhibited a ridge of high values extending from 20%‐150°C to 30%‐200°C, and declined for brittle, expanded products made at low moisture and high temperature and for soft products made at high moisture.
SCRAPED SURFACE HEAT EXCHANGERS
Authors: HÄRRÖD MAGNUS
Published: February 2007

In this literature survey flow patterns, mixing effects, heat transfer and power required for rotation in scraped surface heat exchangers (SSHE) are thoroughly discussed, with the emphasis on assumptions and results, while the principal design of different SSHEs are only briefly discussed.

The flow patterns control the desired radial mixing and the undesired axial mixing. the flow in a SSHE can be regarded as the sum of an axial flow and a rotational flow. the axial flow is laminar and the rotational flow is laminar or vortical.

With laminar flow the radial mixing is poor, which causes poor heat transfer and allows the axial flow profile to control the residence time distribution. the precise onset of vortical flow in a SSHE is hard to predict. the vortical flow makes the radial mixing very efficient, giving good heat transfer and perhaps plug flow behavior. However, vortical flow also causes axial mixing which reduces the apparent heat transfer coefficient and increases the residence time distribution.

The power required to rotate the shaft and blades is mainly determined by the design of the blades.
AVERAGE SPECIFIC CAKE RESISTANCE DETERMINED IN the PRESENCE of SEDIMENTATION to FILTRATION of STARCH SLURRY UNDER CONSTANT PRESSURE
Authors: TAKAI RIKUO , ABE HIROSHI , WATANABE HISAHIKO , HASEGAWA HIROSHI , SAKAI YOSHIO
Published: February 2007

An equation for predicting filtration flow rates in the presence of sedimentation at constant pressure drop was developed. It was applied to determine the average specific cake resistance infiltration of starch slurries at 18.8 to 115 kPa pressure drop range. At these conditions, corn, potato and sweet potato starch filter cakes were incompressible but wheat starch cake was compressible.
EXPERIMENTAL VERIFICATION and USE of PRESSURIZED CAN MODELS
Authors: BREWBAKER PHILIP L. , HENDERSON JERALD M.
Published: February 2007

The results of an experimental investigation of the strength characteristics of pressurized food cans are compared with existing models of thin‐walled cylinders as they pertain to the common unbeaded can. After using the data to establish the empirical quantities in the models, good agreement was found between theory and experiment. the models were then used to predict strength characteristics of hypothetical cans.
METHODS to DISTINGUISH BETWEEN LAMINAR and VORTICAL FLOW IN SCRAPED SURFACE HEAT EXCHANGERS
Authors: HÄRRÖD MAGNUS
Published: February 2007

The transition between laminar and vortical flow has been investigated in scraped surface heat exchangers (SSHEs), using new methods based on viscosity and temperature measurements.

The transition occurred close to the critical Reynolds number for annular flow of Newtonian fluids. Thus, the methods used to predict the viscosity can be successfully applied to SSHEs despite the very complex flow behaviour of the products, the complex geometry of the SSHEs, and the heat transfer in the SSHEs.

In industrial applications, the transition can be detected using the new method based on temperature measurements at the outlet of the SSHEs together with some calculations. This is a very important result, since with this “sensor” the flow pattern can be controlled towards the optimal flow pattern in SSHEs, which in turn is a fundamental requirement when the taste of aseptic products containing particulates are to be improved by the introduction of continuous sterilization.
NATURAL CONVECTION HEAT TRANSFER BETWEEN NON‐NEWTONIAN FLUIDS and an IRREGULAR SHAPED PARTICLE1
Authors: ALHAMDAN A. , SASTRY S.K.
Published: February 2007

Natural convection heat transfer was investigated between aqueous solutions of sodium carboxymethylcellulose (modeled as power law fluids) and a mushroom shaped particle, under transient conditions, with various initial temperature differences. Convective heat transfer coefficients (h) were observed to decrease over time due to thermal equilibration. the average value of h was significantly higher for heating (75 to 310 w/m2‐C) than for cooling (22 to 153 w/m2. C), and decreased with increasing viscosity (CMC concentration). For the lower viscosity ranges, h increased significantly with increasing initial temperature difference. Correlations were developed between Nusselt number and generalized Rayleigh and Fourier numbers.
AN APPROACH to STUDY and MODEL the HYDRODYNAMIC CLEANING EFFECT
Authors: BERGMAN BERT‐OVE , TRAGARDH CHRISTIAN
Published: February 2007

A sensor has been developed for continuous measurements of the removal of deposit. the sensor, which was based on heat transfer measurements, was also able to measure the wall shear stress.

The device was used to study the mechanical effect during cleaning. It was found that the removal rate of deposits, at a surface, could be scaled by the mean wall shear stress. Measurements were performed under both laminar and turbulent flow conditions. the turbulent fluctuations did not influence the removal rate.
PARTICLE RESIDENCE TIME DISTRIBUTIONS IN A MODEL HORIZONTAL SCRAPED SURFACE HEAT EXCHANGER1
Authors: LEE JUN H. , SINGH RAKESH K.
Published: February 2007

Residence times and their distribution characteristics of potato cubes with aqueous solutions of sodium carboxymethyl cellulose (CMC), simulating non‐Newtonian fluid foods, in a horizontal scraped surface heat exchanger (SSHE) were investigated. Minimum and maximum normalized particle residence times (NPRTs) and standard deviations of mean values were not significantly affected by the particle concentration while mean NPRTs of up to 10% particle concentration were signficantly lower than those of 20–40% particle concentrations (P < 0.05). Mean NPRTs were significantly influenced by process parameters including concentration of carrier, viz., viscosity, mutator speed and particle size (P< 0.001) as well as 2‐way interactions among flow rate, mutator speed and particle size (P < 0.05 or 0.001). Furthermore, most of the individual particle residence time distributions in a horizontal SSHE flow could be described by either normal or gamma distribution models.
ELECTRICAL CONDUCTIVITIES of SELECTED SOLID FOODS DURING OHMIC HEATING1
Authors: PALANIAPPAN SEVUGAN , SASTRY SUDHIR K.
Published: February 2007

Electrical conductivities of three vegetable and two meat samples were determined by subjecting them to a constant voltage power supply in a static ohmic heating device. Conductivities of vegetable samples were increased by soaking them in salt solutions, while soaking in water resulted in reduced conductivity due to leaching of electrolytes. Conductivities under ohmic heating conditions increased linearly with temperature. When field strengths were decreased, the conductivity‐temperature curve gradually became nonlinear, and under conventional heating conditions, a sharp transition was observed.
MATHEMATICAL MODELING and EXPERIMENTAL STUDIES ON OHMIC HEATING of LIQUID‐PARTICLE MIXTURES IN A STATIC HEATER1
Authors: SASTRY SUDHIR K. , PALANIAPPAN SEVUGAN
Published: February 2007

Understanding of the ohmic heating of liquid‐particle mixtures requires preliminary study and model development within a static heater. A mathematical (3D finite element) model was developed for prediction of temperatures of mixtures of liquids and multiple particles within a static heater. Experiments were conducted using cubic potato particles within sodium phosphate solutions, for various particle sizes, orientations, concentrations, and liquid conductivities. the mathematical model was found to yield satisfactory prediction of experimental trends. Critical parameters affecting the relative heating rates of particles and liquid were the conductivities of the two phases, and the volume fraction of each phase. Ohmic heating appears most promising with high‐solids concentration mixtures.
A MODEL FOR HEATING of LIQUID‐PARTICLE MIXTURES IN A CONTINUOUS FLOW OHMIC HEATER1
Authors: SASTRY SUDHIR K.
Published: February 2007

Design of safe thermal processes in a continuous flow ohmic heater requires mathematical model development, since temperature monitoring of particles in continuous flow is not presently possible. A mathematical model previously developed and verified for a static heater was modified to predict temperatures of fluids and particles within a continuous heater with high particle concentration suspensions. Results for constant voltage simulations indicate that the presence of large populations of low electrical conductivity particles results in slow heating of the entire mixture rather than a single phase alone. In all these cases, particles tend to heat faster than the liquid. However, if isolated low‐conductivity particles enter the system, the danger of underprocessing exists; hence particle conductivity is a critical control point. Simulations also indicate the role played by residence time distribution and liquid‐particle heat transfer coefficients in the above cases.
DETERMINATION of RESIDENCE TIME DISTRIBUTION of NONSETTLING FOOD PARTICLES IN VISCOUS FOOD CARRIER FLUIDS USING HALL EFFECT SENSORS
Authors: TUCKER GARY S. , WITHERS PETER M.
Published: February 2007

Hall effect sensors were used to determine residence time distributions for diced carrot particles in 4% Colflo 67 carrier fluid. Four sensors at either end of a 3.2 m long 2 in. IDF tube viscometer allowed residence times to be measured for carrot particles incorporating a ceramic magnet. Mean particle residence times were greater than mean bulk residence time for 8 mm diced carrots, whereas 15 mm carrots showed trials in which particles travelled faster than the bulk fluid. Increasing concentration of 15 mm diced carrots from 3.25, 6.30, 9.16 to 11.85% w/w resulted in decreasing mean particle residence times from 17.6, 17.0, 15.9 to 14.3 s, with minimum residence times of 16.4, 16.2, 14.8 and 13.4 s, respectively. This sensing technique operates through stainless steel, providing applications for UHT foods containing particles. In addition, the technique was not affected by high particle concentration, and will operate for any distribution of particle size, shape or type.
ON UPSCALING A CURD PARTICLE MODEL to BATCH PROCESSING SCALE
Authors: AKKERMAN J.C. , DE GEE M. , SCHENK J.
Published: February 2007

Drainage of curd is the separation of solid curd grains and whey, an essential process step in making cheese. It is difficult to model this process by use of current consolidation theories, mainly because of the considerable loss of whey by the curd grains themselves during the expulsion of whey from pores between the curd grains. As an alternative we have studied a model that takes the expression of a single curd grain as a starting point. By analyzing experimental results of a column filled with uniform curd grains drained in radial direction while being under axial external pressure, we study the question to which extent this model might be used to predict the change of porosity with time. It appeared that the model gives reasonable results at low external pressures. At high external pressures the model proves to be inadequate. In the intermediate pressure range the model predicts too fast an expression of the curd grains, although a liquid pressure gradient between the center and the outside of the curd column could not be detected. This suggests the existence of isolated pores, or a geometric limitation of the deformation of curd grains in a curd bed.
CHARACTERIZATION of SINGLE PARTICLE TUBE‐FLOW BEHAVIOR AT ELEVATED TEMPERATURES
Authors: GRABOWSKI S. , RAMASWAMY H.S.
Published: February 2007

The single particle flow behavior of food (carrot, parsnip and potato cubes) and Nylon spheres was investigated in simulated holding tubes at different temperatures under pressurized (110C) and nonpressurized (80 and 100C) flow conditions using different carrier fluids (water and 2, 3 and 4% starch suspensions). It was found that the particle to fluid velocity ratio (up/u) was a function of carrier fluid effective viscosity, temperature and flow rate, and particle relative size, density and shape. the maximum value of up/u ranged from 0.4–1.9 which increased almost linearly with temperature showing no specific deviations in the flow behavior of particles as conditions changed from the nonpressurized (>100C) to pressurized (110C) flow. In dimensionless form, the particle to fluid velocity ratio (mean and maximum) as well as particle Reynolds number were found be functions of generalized fluid Reynolds number, particle Archimedes number, particle to tube diameter ratio and particle sphericity.
EFFECT of PLASTICIZER LEVEL and TEMPERATURE ON WATER VAPOR TRANSMISSION of CELLULOSE‐BASED EDIBLE FILMS1
Authors: CHINNAN MANJEET S. , PARK HYUN J.
Published: February 2007

This study was conducted to determine water sorption isotherms of cellulose‐based films made from methyl cellulose (MC) and hydroxypropyl cellulose (HPC), and to evaluate the effect of plasticizer concentration and temperature on water vapor permeability coefficient in those films. the equilibrium moisture contents of MC film and HPC film increased slowly with an increase in water activity (aw) up to 0.75, but increased greatly after 0.75 aw. the water vapor permeability coefficient of HPC film increased as the concentration of polyethylene glycol (PEG) increased; however, the water vapor permeability coefficient of MC film which contained 0.22 ml PEG/g cellulose was lower than of films which contained no or higher PEG. an Arrhenius‐type relationship was fitted to examine temperature dependence of water vapor permeability coefficients of cellulose films. the edible films studied exhibited relatively low activation energies (14.56–16.43 kJ/mol) compared with typical food packaging materials.
DIMENSIONLESS CORRELATIONS FOR MIXED and FORCED CONVECTION HEAT TRANSFER to SPHERICAL and FINITE CYLINDRICAL PARTICLES IN an ASEPTIC PROCESSING HOLDING TUBE SIMULATOR
Authors: AWUAH G.B. , RAMASWAMY H.S.
Published: February 2007

Dimensionless correlations for estimating heat transfer coefficients for spherical and finite cylinders under mixed and forced convection heat transfer regimes were individually investigated using multiple regression of statistically significant dimensionless groups. Food and model particles were subjected to heat treatments in an aseptic processing holding tube simulator (carrier fluid: 0, 0.5, and 1.0%, carboxymethyl cellulose solutions, w/w basis; temperature: 90 to 110C; flow rate 1.0 to 1.9 × 10−4 m3/s). the type of test material was found to have a significant effect on the Nusselt number, and hence developed correlations. Introducing a diffusivity ratio defined as the ratio of particle‐to‐fluid thermal diffusivities was found to consistently improve developed models. Excellent correlations (R2≥ 0.97) were obtained between the Nusselt number and dimensionless groups for all models. Natural convection in heat transfer correlations in situations where forced convection is expected to be the dominant mechanism was accommodated.
OPTIMIZATION of PROTEIN PRECIPITATION IN ACID WHEY OBTAINED FROM SMALL RUMINANT'S MILK
Authors: PINTADO MANUELA E. , MALCATA F. XAVIER
Published: February 2007

Attempts to maximize the precipitation yield of the major proteins via thermal processing of whey obtained from milks of Portuguese native breeds of ewes and goats was done using heating time, heating temperature, and stirring rate as independently manipulated variables. the experiments were planned according to a full factorial design with eight corner points, six axial points, and three replicated center points. Assessment of the fractions of β‐lactoglobulin and α‐lactalbumin removed by precipitation was done by gel filtration chromatography. the loci of the values of each manipulated variable (when the remaining two are fixed) which lead to critical points were obtained for both proteins, and the nature of such points was found. Comparative evaluation of the various loci has indicated that maxima for the precipitation of α‐lactalbumin and β‐lactoglobulin from both whey sources exist. However, a maximum value for the selectivity of precipitation of β‐lactoglobulin relative to that of α‐lactalbumin (within physically realizable conditions and without extrapolation from the experimental range covered) exists only for goat's whey (at a temperature of ca. 92C, heating time of ca. 46 min, and stirring rate of ca. 79 r.p.m.).