bluuebunny/crossref_metadata_2025 huggingface dataset:
Enzyme activities in quinoa (Chenopodium quinoa)
Authors: LORENZ K. , NYANZI F.
Published: July 2010

The amylase, protease, cellulase and hemicellulase activities were determined in the flour of untreated quinoa seeds, and again after mechanical abrasion and after water and heat treatment to remove saponins. Optimum pH for amylase activity was approximately 5.0 and for protease activity it was 4.2

In comparison with a non‐malted wheat flour, which generally would have a Braben‐der unit (BU) reading of over 2000 in the Amylograph, values for quinoa were very low, indicating a high α‐amylase activity. Mechanical abrasion, which removed about 18% of kernel weight, increased α‐amylase and protease activities of the seeds because of removal of layers low in activity. Only toasting of seeds at 170°C after saponin removal reduced activities of these enzymes substantially.

Total amylase, cellulase and hemicellulase activities were highest in the unprocessed seeds. Activities decreased after mechanical abrasion of seeds. Heat treatment after saponin removal caused a further decrease in activity of these enzymes.
Objective measurement of banana pulp colour
Authors: WAINWRIGHT H. , HUGHES P.A.
Published: July 2010

Two methods for determining the colour of banana pulp were compared by using either visual matching with colour charts or a portable tristimulus colorimeter. Pulp colour of ripe and unripe bananas was evaluated in both the darker central carpellary zone and the outer pulp zone near the skin of the fruit. Colour coordinates L* and b* were highly correlated (r = ‐0.89 and 0.87 respectively) with the visual matching colour charts, the central carpellary region giving higher correlations than the outer pulp zone. Results obtained show that the colour of banana pulp can be objectively measured by the combined use of L* and b* coordinates determined in the carpellary zone. The potential use of a reproducible and defined method for determining banana pulp colour is discussed.
Extraction of ginger rhizome: kinetic studies with acetone
Authors: SPIRO M. , KANDIAH M.
Published: July 2010

Ground sieved Jamaican ginger rhizome has been treated with acetone under various conditions and, in each case, the concentration of [6]‐gingerol extracted was measured as a function of time. The results could be expressed by two intersecting first‐order plots and an initial intercept, representing very rapid initial extraction, followed by a fast stage and a subsequent slow stage. At 30°C the rate constant of the slow stage was c. 95 times smaller than that of the fast stage and its activation energy was 3.6 times larger. The fast stage was not affected by solvent flow into the ginger particles, or by an increase in the stirring speed. These findings, together with the fact that both first‐order rate constants were inversely proportional to the square of the radius of the particles, pointed to [6]‐gingerol diffusion through the solid ginger as the rate‐determining step. The data could also be fitted by the equation of So and MacDonald (1986). The relevance of the research to the industrial production of ginger oleoresin is pointed out.
Reduction of Streptococcus thermophilus in a whey protein isolate by low moisture extrusion cooking without loss of functional properties
Authors: QUÉGUINER C. , DUMAY E. , CAVALIER C. , CHEFTEL J. C.
Published: July 2010

A whey protein isolate powder (WPI) (4–5% water) inoculated with 5x105 viable Streptococcus thermophilus per g, was continuously processed in a twin screw extruder under the following conditions (barrel length = 500 or 1000 mm; screw profile = forward transport and compression elements; moisture content during extrusion = 4–5%; feed rate = 10 kg h‐1; barrel temperature (Tb) = 80–204°C; speed of screw rotation = 50 r.p.m.). The minimum residence time determined by pulse injection of erythrosin was 20–25 s (500 mm barrel) or 35–40 s (1000 mm barrel).

Reduction values of viable Streptococcus thermophilus of 104.2‐fold (500 mm barrel, Tb= 143°C) or 104.9‐fold (1000 mm barrel, Tb= 133°C) were obtained without any modification of protein solubility or gelling properties. WPI extruded at the highest barrel temperatures (182–204°C) underwent limited browning and reduction of protein solubility. Gel permeation and hydrophobic interaction chromatography of the soluble constituents did not show any aggregates of β‐lactoglobulin or α‐lactalbumin.

Gels prepared from control or extruded WPI (Tb 143°C with a barrel length = 500 mm or Tb 133°C with a barrel length = 1000 mm) were identical, as judged by scanning electron microscopy and rheological evaluations.
The heat stability and isoenzyme composition of peroxidases in Ohane grapes
Authors: ROBINSON D. S. , BRETHERICK M. R. , DONNELLY JUDITH K.
Published: July 2010

Soluble and ionically bound peroxidases have been obtained from homogenized Ohane grapes. The soluble fraction contained the highest level of peroxidase activity and accounted for approximately 87% of the total enzymic activity. Plots of the percentage of heat inactivation for the grape peroxidases against time were non‐linear with approximately 90% of the peroxidase activity being destroyed after 10 min at 80°C. Following heat inactivation there was no significant regeneration of enzymic activity. Using isoelectric focusing six isoperoxidases with isoelectric points ranging from approximately pI 3.5 to 9.8 were detected.
An investigation of enzyme activities found in thaumatin preparations
Authors: RAMSOHOYE PAMELA V. , KOZLOV I. A.
Published: July 2010

A new alkaline cathodic gel has been developed which improves on the acidic cathodic gel of Reisfeld, Lewis and Williams (1962) when resolving thaumatin isoproteins in commercial thaumatin by electrophoresis. This new gel was used in the investigation of protease and esterase activities in commercial thaumatin and thaumatin isoprotein preparations. Enzyme activity stainings of the thaumatins on the new gel indicate that these activities do not belong to thaumatin but to contaminating enzymes. Other data, such as the decrease in the protease and esterase activities as a result of further purification of the thaumatins and the titration of the proteolytic activities with the specific inhibitor, E‐64, also support this conclusion.
Physical properties of cassava mash
Authors: GEVAUDAN A. , CHUZEL G. , DIDIER S. , ANDRIEU J.
Published: July 2010

Sorption and thermophysical properties (desorption curves, density and specific heat) of native and gelatinized cassava mash and of cassava starch were determined, in order to gain a better understanding of the heat and mass‐transfer phenomena involved in gari cooking and drying.

Desorption isotherms of native cassava mash are given at four temperatures from 40 to 90°C; the experimental data were described using the GAB model with a maximum root mean square error (RMS) of 5%.

The net desorption enthalpy, calculated from the desorption data, decreases from 902.0 to 80.2 kJ/kg when the moisture content increases from 0.04 to 0.24 kg of water/kg dry matter. Desorption curves are not significantly affected by the degree of gelatinization of the starch, but at constant water activity, native cassava mash has a higher equilibrium moisture content than the other samples.

The density of cassava mash increases from 1239 to 1509 kg/m3 when it is dehydrated from 51.8 to 6% (wet basis), and the specific heats of dry cassava starch and dry cassava mash, determined by differential scanning calorimetry, vary linearly over the temperature range ‐20°C to 96°C from 1.128 to 1.760 and from 0.979 to 1.591 kJ/kgxK.
The palm oil bleaching capacity of various Nigerian clay deposits
Authors: OKPALA K. O. , NWOKE M. N.
Published: July 2010

The ability of clay deposits from six different locations in Nigeria to bleach palm oil was assessed. Each clay was analysed for gross mineral composition. Degummed and steam‐sparged palm oil was heated with different quantities of each fine clay for 30 min. The degree of bleaching was determined by comparing the absorbance of residual pigment at 452 nm with that of unbleached oil. Performance was assessed with a modified form of the Freundlich adsorption isotherm (X/M = KCn), where X/M is the mass of pigment adsorbed per unit weight of adsorbent, C is the equilibrium concentration of pigment, and the constant K provides an index of performance for each clay. The exponent n was 2 for all clays, and K values varied from 120 to 2950, apparently with the Fe2O3 content of the clay. Clays with high iron content should be tested further, for use in bleaching palm oil.
Degradation of polysaccharides by immobilized depolymerizing enzymes
Authors: TURECEK P. L. , PITTNER F. , BIRKNER F.
Published: July 2010

Polysaccharides in fruit and vegetable juices can be efficiently degraded using co‐immobilized amylolytic and pectolytic enzymes combined with naringinase. The enzymes were immobilized on silica carriers for use in fining procedures to remove cloudiness.
Changes in the electrical conductivity of foods during ohmic heating
Authors: HALDEN K. , DE ALWIS A. A. P. , FRYER P. J.
Published: July 2010

Ohmic heating is a food processing operation in which heat is internally generated within foods by the passage of alternating electric current. The process enables solid particles to heat as fast as liquids, thus making it possible to use High Temperature Short Time sterilization techniques on particulate foods. Ohmic heating rates are critically dependent on the electrical conductivities of the foods being processed, about which little information is available. This paper reports experiments to determine the changes in electrical conductivity which occur during ohmic heating of some common foods. A number of effects which occur during conventional heating, such as starch transition, melting of fats and cell structure changes, are shown to affect the electrical conductivity. In some cases the presence of an electric field induces enhanced diffusion of cell fluids in the food which increases the rate of change of conductivity with temperature above that found by conventional heating. Preheating is found to increase the electrical conductivity of some foods, making them acceptable for ohmic processing.
An improved high‐pressure homogenizer for making fine emulsions on a small scale
Authors: BURGAUD I. , DICKINSON E. , NELSON P. V.
Published: July 2010

A reliable high‐pressure laboratory homogenizer is described for the small‐scale production of emulsions with highly reproducible droplet‐size distribution. A key feature of the design of this ‘jet homogenizer’ is the inclusion of separate chambers for oil and aqueous phases, thereby eliminating the necessity for premixing prior to homogenization, with its associated problems of air incorporation. To illustrate the performance characteristics of the jet homogenizer, data are presented for the effect of homogenization pressure and equipment dimensions on the droplet size of n‐tetradecane‐in‐water emulsions stabilized by sodium caseinate.
Chemical and nutritional quality of Indonesian dried‐salted mackerel (Rastrelliger kanagurta)
Authors: MARUF F. W. , LEDWARD D. A. , NEALE R. J. , POULTER R. G.
Published: July 2010

Indonesian mackerel (Rastrelliger kanagurta) were sun dried or salted and sun dried and stored at 30°C for up to 20 weeks in air. During processing and storage polyunsaturated fatty acids oxidized to form thiobarbituric acid (TBA) reactive substances and fluorescent compounds. TBA values increased with increasing salt content (range 2.3–20.7%). Positive, highly significant correlations were found between the odour of the stored products and both fluorescent pigment production and the degree of browning. Amino acid analysis indicated loss of lysine, glutamic acid, serine, histidine, arginine and the sulphur containing amino acids, but these losses were far too small to account for the massive decreases found in net protein utilization (NPU) of the stored products, measured by rat‐feeding trials. The latter were highly correlated with the fluorescent pigment content and degree of browning in products of intermediate (∼ 14%) salt content.
Amino acid composition of whole mackerel (Scomber scombrus) stored anaerobically at 20°C and at 2°C
Authors: HAALAND H. , ARNESEN E. , NJAA L. R.
Published: July 2010

Total amino acid composition of whole mackerel (Scomber scombrus) and of milt and roe from mackerel stored at different conditions were studied. During storage at low temperature, no obvious changes were found. When stored at high temperature (20°C), the contents of several of the amino acids decreased, and phenylethylamine, tyramine, putrescine, histamine and cadaverine were formed the formation of cadaverine was higher than the loss of lysine.
A comparison of modified atmosphere and vacuum skin packing for the storage of red meats
Authors: TAYLOR A. A. , DOWN N. F. , SHAW B. G.
Published: July 2010

The performances of two commercially available packaging systems for prolonging the shelf‐life of fresh meat were compared at 1°C and during simulated retail display. Beef and pork loin steaks in modified atmosphere packs (MAP), containing 75% O2 and 25% CO2, developed an initial bright red (beef) or pink (pork) colour, which gradually changed to brownish‐red or ‐pink after 12 days; similar samples in vacuum skin packs (VSP) remained purple‐red throughout the storage period. Off‐odours developed more rapidly in MAP (8–12 days), possibly due to more extensive growth of Brochothrix thermosphacta and the effects of aerobic conditions on the metabolites of lactic acid bacteria, which predominated in both types of packs. Evidence of rancidity, using thiobarbituric acid assay, was demonstrated in MAP beef after approximately 8 days, but not in VSP. Drip losses in MAP increased after 6 days' storage, but remained generally low in VSP. Physical texture (shear force values of cooked samples) of beef was unaffected by packaging method, but pork in VSP was significantly more tender (P < 0.001) than in MAP.
Effects of controlled atmospheres on microbial spoilage, electrolyte leakage and sugar content of fresh ‘ready‐to‐use’ grated carrots
Authors: CARLIN F. , NGUYEN‐THE C. , CHAMBROY Y. , REICH MARYSE
Published: July 2010

The effects of controlled atmospheres (CO2 concentrations ranging from 0.03 to 40% and O2 concentrations ranging from 21 to 1%, measured in pack) were studied on fresh ‘ready‐to‐use’ grated carrots, stored at 10°C. High CO2 or low O2 conditions favour the growth of lactic acid bacteria (LAB) on grated carrots, but not in a sterile carrot medium, and induce an increased potassium ion leakage. A 25% CO2 and 2% O2 atmosphere improves retention of sugars.

Grated carrots were inoculated by a strain of Leuconostoc mesenteroides, which caused increased potassium ion leakage and exudation only under an atmosphere containing 40% CO2 and 10% O2.

The origin of the spoilage of ‘ready‐to‐use’ grated carrots is discussed.
Water desorption isotherms of two varieties of sweet potato
Authors: DIAMANTE L. M. , MUNRO P. A.
Published: July 2010

Water desorption isotherms were determined for New Zealand sweet potato at 25, 40 and 55°C, and for Philippines sweet potato at 28°C. The isotherms were sigmoid in shape and of type II according to the BET classification. The data were fitted to eight two‐parameter equations reported in the literature. The effect of water activity, aw, and temperature, T°C, on the equilibrium moisture content, Me g water/100g dry solids, was best described for New Zealand sweet potato by: Me = 20.51 T‐0.204 (aw/(1‐aw)0.39 for aw= 0.06–0.81
Extraction of ginger rhizome: kinetic studies with dichloromethane, ethanol, 2‐propanol and an acetone—water mixture
Authors: SPIRO M. , KANDIAH M. , PRICE W.
Published: July 2010

The kinetics of extraction of [6]‐gingerol from ground Jamaican ginger rhizome have been determined at 30°C in dichloromethane, ethanol, isopropanol and an 80% (v/v) acetone + 20% (v/v) water mixture. The extractions all proceeded in three stages: an initial ‘washing’ stage, a fast stage and a subsequent much slower stage. The rate of extraction of hexahydrocurcumin in ethanol was found to follow a simpler pattern. From the first order plots, the diffusion coefficients of the extracted solubles within the ginger particles were calculated. They varied inversely with the 0.6 power of the solvent viscosity, which explained why the rates of [6]‐gingerol extraction decreased in the sequence: acetone < acetone + water < dichloromethane < ethanol < isopropanol. These results show that solvents of low viscosity should be chosen to attain fast extraction rates. The diffusion coefficient of [6]‐gingerol was also measured at 30°C in pure acetone, ethanol and isopropanol. The values in these bulk solvents were 13–20 times greater than the diffusion coefficients of [6]‐gingerol within the ginger particles for the fast stage and over 900–1800 times greater than those for the slow stage. These hindrance factors quantify the effect of the ginger matrix environment on internal diffusion.
Catalysis of the reaction between sorbic acid and thiols by surfactants
Authors: WEDZICHA B. L. , ZEB A.
Published: July 2010

Sorbic acid reacts slowly with simple thiols at 80°C. The reaction involves nucleophilic attack on the sorbic acid molecule by the thiolate anion. Second order rate constants for the reactions of mercaptoethanol, mercaptoacetic acid, cysteine and glutathione are, respectively, 0.86, 0.68, 2.3 and 2.5 M‐1 h−1 at 80°C and independent of pH in the range pH 3.7–5.7. The effects of dodecyltrimethylammonium bromide (DoTAB), sodium dodecyl sulphate (SDS), lecithin, datem ester (diacetyltartaric acid ester of C18 monoglyceride) and Tween 80 on the initial rates of these reactions at pH 5.0 are reported. The greatest catalytic effect was shown by DoTAB, giving a maximum enhancement of rate by a factor of 21.4 for the mercaptoethanol reaction and 4.6 for the glutathione reaction. SDS was much less effective. The nonionic surfactants all behaved as catalysts. The mechanism of the surfactant‐catalysed reaction is discussed. Kinetically derived stoichiometries of binding of the solutes in question to DoTAB micelles depend on surfactant concentration, and for the thiols used (mercaptoacetic acid, cysteine and glutathione) it is found that each thiol molecule is associated with at least 10 surfactant molecules making up the micelles for surfactant concentrations greater than or equal to 50 mM. The implications of micellar catalysis to food additive‐food component interactions are considered.
Purification and preliminary characterization of five serine proteinases produced by Brevibacterium linens
Authors: HAYASHI K. , CLIFFE A. J. , LAW B. A.
Published: July 2010

Five proteinases were purified from culture filtrate of Brevibacterium linens by a series of column chromatography and found to be homogeneous by polyacrylamide gel electrophoresis. All appear to be serine proteinases, being inactivated by phenyl‐methylsulphonyl fluoride and not by EDTA or p‐chloromercuribenzoic acid. They were all active against casein in alkaline pH (pH optimum of 11.0) and specific activity was within the range 2.66–3.23 units mg−1 protein. Proteinases C, D and E were more stable in higher temperature and acidic pH than proteinases A and B. Molecular weights estimated by gel filtration were 37000, 37000, 44000, 127000 and 325000 for proteinases, A, B, C, D and E, respectively.
Partial characterization of the in situ activity of pectinesterase in Bramley apple
Authors: KING KAREN
Published: July 2010

The characteristics of pectinesterase (PE) have been examined in waste material (peel, cores and offcuts) obtained from Bramley seedling apples barn stored for 2, 4 and 12 weeks. A crude enzyme extract was prepared by suspending the dried and milled apple waste in 0.1 m NaCl at pH 8.5. The activity of PE under standard assay conditions of 0.5% apple pectin, 0.1 m NaCl, pH 8.5 and 30°C was low, between 4 and 8 units g−1 dry matter, but activities up to 60 units g−1 dry matter were obtained at higher temperatures. The optimum temperature was 60°C with the enzyme stable up to 40°C with 5 min heating. The mean activation energy for PE in the three samples was calculated at 39.2 kJ mol−1 K−1. The optimum pH was high at 10.0 probably due to the PE assay measuring the extraction/solubilization and stability of the enzyme in addition to its activity. Optimum activity was obtained in 0.15 m NaCl with optimum stability at 0.5 m.
Evaluation of cooking time and quality of seven diverse cowpea (Vigna unguiculata (L.) Walp.) varieties
Authors: DEMOOY B. E. , DEMOOY C. J.
Published: July 2010

Seven cowpea (Vigna unguiculata (L.) Walp.) varieties, which were part of a larger collection evaluated in agronomic field trials in Botswana, were selected for characterization of cooking time and quality. Newly harvested seed was kept in the open air for 2 weeks, then stored at 4°C and 40% relative humidity for 3 months. Duplicate samples were tested for cooking time with and without 12‐h prior soaking. Varieties showed differences (P < 0.01) in cooking time and response to soaking, although the overall effect of soaking was insignificant. Cooking times ranged from 29 to 64 min without soaking and 36 to 56 min after soaking, with small‐seeded varieties having the longer cooking times. The seed coat of some varieties readily became soft, but others remained tough or split before finally softening.
Carotenoid composition and vitamin A value of some native Brazilian green leafy vegetables
Authors: MERCADANTE ADRIANA Z. , RODRIGUEZ‐AMAYA DELIA B.
Published: July 2010

The composition of carotenoids in five native Brazilian leafy vegetables was determined. The ranges of total carotenoid contents of Amaranthus viridis, Lepidium pseudodidymum, Xanthosoma spp., Sonchus oleraceus, and Portulaca oleracea were 347–468, 237–280, 225–361, 149–334 and 71–109 μg g−1, with lutein and β‐carotene predominating. The mean β‐carotene contents (μg−1) and vitamin A values (retinol equivalents REg−1) were 110 and 18.4, 84.6 and 14.1, 67.3 and 11.2, 62.9 and 10.5, 29.8 and 4.99, respectively. The leaves contained 54–61% of lutein plus violaxanthin, 24–34% of β‐carotene, 10–14% of neoxanthin and traces of zeaxanthin and α‐crypto‐xanthin. The native leafy vegetables were richer sources of provitamin A than the cultivated leafy vegetables analysed previously, justifying their commercial production.
Evaluation of a general purpose abrasive mill for pearling of coarse cereals and dehusking of pulses
Authors: SAHAY K. M.
Published: July 2010

A general purpose abrasive mill, developed to pearl and dehusk cereals and pulses, has integral milling and cleaning chambers and a 10‐grinding wheel rotor driven by a 3.7 kW motor. Its capacity is between 96 and 340 kg h−1, depending upon the grain being handled, with a maximum dehulling efficiency of 75%. The cost of processing varied from Rs 4.5 to 9.2 per tonne of feed. It could be owned, operated, and manned by small‐scale processors in rural and semi‐urban areas.
Tensile and compressive strengths of two horticultural packaging materials: cane and palm frond
Authors: ADEGOROYE A. S. , ENIAYEJU D. E. , AJIBOLA O. O.
Published: July 2010

Tensile and compressive strengths of cane and palm frond rachis were measured fresh and after ambient indoor, sun, and oven drying. Sun drying gave the best tensile strength in palm frond, but still much less than cane; it was almost as effective as oven drying for cane. The compressive strength of frond was much less than for cane, but a combination of both might be useful in strength over frond baskets and in cost over cane baskets.
Mechanisms of gelation of sardine proteins: influence of thermal processing and of various additives on the texture and protein solubility of kamaboko gels
Authors: ROUSSEL H. , CHEFTEL J. C.
Published: July 2010

Surimi prepared from freshly caught sardines was mixed with NaCl and other additives and used to prepare kamaboko gels. Protein‐protein interactions involved in the setting (at 4 or 37°C) and/or the cooking (at 90°C) gelation steps were investigated (i) by assessment of kamaboko texture as a result of the type and concentration of additive added; (ii) by partial solubilization of kamaboko gels in buffers containing mercaptoethanol, sodium dodecyl sulphate (SDS) and/or urea, followed by determination of the soluble protein constituents by polyacrylamide gel electrophoresis. Cooked gels of high elasticity and of varying rigidity and gel strength were obtained in the 73–80% water range. Adequate gel texture required a NaCl content of 1.7–3.5% and a pH range of 6.4–8.4. Low concentrations of reducing agents (mercaptoethanol, dithiothreitol, cysteine) or of divalent cations (Ca2+, Mg2+) improved the texture of gels obtained by setting at 37°C with and without subsequent cooking at 90°C. On the other hand, the addition of N‐ethyl maleimide or of ethylene diamine tetra‐acetate led to texture deterioration after cooking. These data demonstrate the involvement of disulphide bonds and of electrostatic interactions in surimi gelation. Gel solubilization experiments indicate that the aggregation of myosin heavy chains through various types of protein‐protein interactions may be responsible for the elastic gel network formed during setting at 37°C (30 min) or 4°C (24h). Strengthening of the gel network after cooking appears to be due to additional disulphide and hydrophobic interactions.
The properties of surimi and kamaboko gels from nine British species of fish
Authors: HASTINGS R. J. , KEAY J. N. , YOUNG K. W.
Published: July 2010

This paper describes the preparation and properties of surimi and derived kamaboko gels from a range of British‐caught species of teleost (or bony) fish including white fish (fillets, trimmings and skeletons), fatty fish and an elasmobranch (or cartilaginous) fish. The data include yields, moisture and fat contents, water‐binding capacities, pH values and Hunter L,a,b colour values as well as sensory and instrumentally measured indices of texture.

Cod, haddock and whiting fillets and trimmings of haddock and whiting yielded surimi and derived gels with functional properties most closely approaching those of the Alaska pollack surimi used as a standard. Saithe gave a gel which was firm and elastic but which had a low water‐binding capacity and was dark in colour. The fatty fish yielded surimi with some potentially useful functional properties but colour and water‐binding capacity were inferior to pollack surimi.
Rancidity and lipid oxidation of dried‐salted sardines
Authors: LUBIS Z. , BUCKLE K. A.
Published: July 2010

Rancidity scores and several chemical assessments of lipid degradation (thiobarbituric acid reactive substances, diene conjugation, fluorescent products, polyene index) were made on three types of dried‐salted sardines stored at three temperatures for 24 weeks. The non‐enzymic browning of the samples was also evaluated. Results from only two of the five indices, i.e. polyene index and the presence of fluorescent products, showed a significant correlation (P < 0.01) with rancidity score.
Changes in the composition of the fatty acids and aldehydes of meat lipids after heating
Authors: FOGERTY A. C. , WHITFIELD F. B. , SVORONOS D. , FORD G. L.
Published: July 2010

The effects of heating at 132°C on the fatty acids and fatty aldehydes of neutral lipids and phospholipids of lean beef, veal, lamb, pork and chicken were studied. Heating caused hydrolysis of the plasmalogens in the phospholipids, and varying amounts of the liberated fatty aldehydes were recovered in the neutral lipid fractions. Beef phosphatidyl choline lost more polyunsaturated fatty acids than that of the other meats. Beef and veal phosphatidyl ethanolamine lost more polyunsaturated fatty acid than that of lamb, pork or chicken, but the effect was obscured by the influx of fatty acids from elsewhere into this fraction after heating.
Extraction of ginger rhizome: kinetic studies with supercritical carbon dioxide
Authors: KANDIAH M. , SPIRO M.
Published: July 2010

The rates of extraction of [6]‐gingerol from ground dried Jamaican ginger rhizomes were determined in supercritical carbon dioxide over the pressure range 128–197 bar (1850–2850 psi) and the temperature range 50–65°C. The CO2 densities varied from 0.415 to 0.775 g cm−3. First‐order plots showed two approximately linear sections with an initial intercept. The first linear section corresponded to a relatively fast initial extraction stage while the last 20% or so of the gingerol was extracted in the much slower subsequent stage. Reducing the ginger particle size by a factor of 3 increased the rate constant of the fast stage nine‐fold. Despite the low viscosity of the supercritical fluid, the rate constants of the fast stage were much smaller than in extractions with organic solvents. Only when the CO2 density was increased to 0.775 g cm−3 did the rate constant of the fast stage rise to a value comparable with, but still smaller than, those in organic solvents of similar density. The rate constants of the later slow extraction stage were also somewhat smaller than the corresponding values in organic solvents at 30°C.
Effect of batch extraction conditions on extraction of polyphenols from rooibos tea (Aspalathus linearis)
Authors: JOUBERT E.
Published: July 2010

The effects of extraction temperature (23, 50, 60, 70, 80 and 90°C), mass ratio of extract: dry tea leaf (5:1 and 10:1) and flow rate of water (0.1 and 0.2m3/h) on extraction of total polyphenols, flavonoids and non‐flavonoid phenols from rooibos tea were determined with a single‐stage batch‐extraction system. Extraction of the different phenolic groups from tea leaves increased significantly with increasing temperature. The increase in total polyphenol extraction was due mainly to increasing extraction of flavonoids. Increasing mass ratio and decreasing flow rate resulted in better extraction of the different phenolic groups. The phenolic content of extract soluble solids also increased significantly with temperature. At extraction temperatures 23 and 50°C, increasing mass ratio resulted in a significant increase in total polyphenol and flavonoid content of the soluble solids. The non‐flavonoid phenol content increased significantly with increasing mass ratio at temperatures above 23°C. Flow rate did not significantly affect the total phenolic and flavonoid content of soluble solids.
Heat of sorption of water in dried fruits
Authors: TSAMI E. , MAROULIS Z. B. , MARINOS‐KOURIS D. , SARAVACOS G. D.
Published: July 2010

The heats of moisture adsorption and desorption in four dried fruits (sultana raisins, figs, prunes and apricots) were estimated from equilibrium sorption data, using the Clausius‐Clapeyron equation in the temperature range 15–60°C. The net isosteric heat of sorption (qst) decreased sharply from about 20 kJ mol−1 water to near zero when the moisture content was increased from 0.05 to 0.50kg water kg−1 dry matter. An exponential function was fitted to the experimental qst values at various moisture contents (X), yielding two characteristic constants (q0 and X0) for each fruit. Mean and total heats of sorption were calculated from the proposed empirical equation, which are useful for enthalpy prediction in food dehydration. The heats of desorption were higher than the heats of adsorption, indicating significant hysteresis in the sorption of water, especially in dried apricots.
Equilibrium moisture content, BET monolayer moisture and crispness of extruded rice‐legume snacks
Authors: CHAUHAN G. S. , BAINS G. S.
Published: July 2010

Extruded Jaya rice‐legume (3:1 w/w) snacks equilibrated at different relative humidities (RH; 10–86%) exhibited similar typical sorption‐isotherms and equilibrium moisture contents (EMC) up to 33% RH. Acceptable crispness was lost above 43% equilibrium relative humidity (ERH) and about 110N breaking strength. The values for the BET monolayer moisture content of various products were almost identical to their initial moisture content, indicating the adequacy of the processing conditions for snacks of satisfactory shelf‐life if packed immediately in moisture‐impermeable packets.
Salting and drying of yellowtail (Trachurus mccullochi Nichols)
Authors: BERHIMPON S. , SOUNESS R. A. , BUCKLE K. A. , EDWARDS R. A.
Published: July 2010

Wet salting of low‐fat yellowtail (Trachurus mccullochi Nichols) using three brine solutions (15%, 21% and saturated salt) and drying of salted fish at 35°C and 50% RH, 45°C and 30% RH, or 55°C and 18% RH was carried out and assessments made of salt and moisture contents, water activity (aw), and sensory properties of dried‐salted fish. Brine concentration during salting and the drying conditions had a significant effect on the drying rate. Brining in saturated brine gave the most rapid rate of reduction in moisture content and the lowest final moisture content during brining, but produced a slower rate of reduction of moisture and higher final moisture content during drying. Fish brined in saturated salt and dried at 55°C was of lower sensory quality.
Thermal treatment of aseptically processed tomato paste
Authors: MALLIDIS C. G. , FRANTZESKAKIS P. , BALATSOURAS G. , KATSABOXAKIS C.
Published: July 2010

The heat resistance characteristics of Bacillus coagulans (NRRL B‐1103) spores suspended in buffer (pH 7.0, 4.5), tomato serum and tomato paste were studied. It was found that the heat resistance of spores was reduced significantly when buffer of pH 4.5, tomato serum or tomato paste was used as suspension medium instead of buffer pH 7.0. This effect was more apparent at higher temperatures. It was concluded that a thermal process of F105°C= 3 min is capable of causing at least 3D destruction of spores of the most heat resistant strains of B. coagulans
The influence of fruit anatomy on ease of peeling of tomatoes for canning
Authors: MOHR W. P.
Published: July 2010

Anatomical features of the outer pericarp region of ripe tomato fruit were correlated with ease of peeling before canning. Fruit of many lines were examined, and were assessed for 11 properties that might be associated with the promotion of peel removal. Highest correlations were found for a steep cell‐size gradient towards the outer surface, and also for an absence of small cells in the mesocarp. Several other features were significantly correlated with the ease of peel removal.
Effect of cooking method on water absorption and ease of dehulling in preparation of African locust beans for Iru
Authors: OYEWOLE O. B. , ODUNFA S. A.
Published: July 2010

Gas boiling or pressure cooking increased the level of water uptake by locust beans over that with firewood cooking, mainly because of sustained heat input. Presoaking in cold water produced no advantage. The boiling times necessary for satisfactory dehulling were 10h using firewood, 6h by gas boiling, and 30 and 50min respectively by pressure cooking at 121 and 115°C.
Water activity of culture media used in food microbiology
Authors: ESTEBAN M. A. , ALCALA M. , MARCOS A. , FERNANDEZ‐SALGUERO J. , DE FERNANDO G. D. GARCIA , ORDOÑEZ J. A. , SANZ B.
Published: July 2010

An improved gravimetric method was used to simultaneously determine (in a single assay) the water activity (aw) of 30 solid and liquid culture media covering the entire useful range of aw in food microbiology, including media recommended for osmophilic, halophilic and xerophilic organisms. The water activities of the media ranged between 0.999 and 0.739. As could be expected, the water activities of the solid media were not affected significantly by the presence of agar. No significant differences were observed either between the gravimetric (20°C) and the cryoscopic measurements (below 0°C) of liquid media of very high aw.
Effect of slaughter method on the progress of rigor of rainbow trout (Salmo gairdneri) as measured by an image processing system
Authors: AZAM K. , STRACHAN N. J. C. , MACKIE I. M. , SMITH J. , NESVADBA P.
Published: July 2010

Rainbow trout (Salmo gairdneri) were slaughtered by AC and DC electrocution, exposure to elevated concentrations of carbon dioxide and by a blow to the head. The fish were subsequently bled and placed in ice.

At regular intervals after slaughter the fish were taken from the ice and placed on a horizontal table with the posterior half of the fish overhanging the edge. The angle which the fish's tail formed with the vertical was used as an index of rigor and was measured by an image processing system. It was found that the stages of rigor were statistically the same for the four different treatments except that the onset of rigor for fish given a blow on the head was delayed.
Effect of length and temperature of storage on the ESR signal from various bones in irradiated chicken carcasses
Authors: GRAY R. , STEVENSON M. H.
Published: July 2010

Eighty‐four whole, fresh chicken carcasses were randomly allocated to three groups of 28. Half of the carcasses within each group acted as controls (0kGy) and the remainder received an average irradiation dose of 5.27 kGy. The carcasses were then stored at either +20°C, +5°C or ‐20°C for periods of 1, 3, 7, 14, 21, 28, 56, 84 or 128 days. Bones from four sites within the carcass (tibia, femur, rib and sternum) were removed and prepared for analysis by electron spin resonance (ESR) spectroscopy. The strength of the ESR signal induced in the bones as a result of gamma irradiation was determined by double integration of these signals. The site from which the bone was removed had a highly significant effect on the ESR signal intensity and this response was highly correlated with bone crystallinity. Neither storage time, temperature nor the interaction of these two variables significantly affected the ESR signal strength in the bones from the four sites within the carcass. Nevertheless, there was a tendency for the signal to decrease with time when the samples were stored in dried from at +20°C.
Co‐operative trial of methods of analysis to detect irradiation treatment of chicken samples: initial trial
Authors: SCOTTER S. L. , HOLLEY P. , WOOD R.
Published: July 2010

The results of a co‐operative trial of methods for detecting irradiated chicken are reported.

Seven laboratories participated in the trial. Participants received bone, skin or flesh from whole birds which had been irradiated at 2.5 and 5kGy and also from control unirradiated birds. The most frequently used method was electron spin resonance (ESR) but other methods used by participants included hydrocarbon profiling and a bacterial screen.

Most participants using ESR methodology estimated the dose received by the chickens to within 1kGy at the lower dose level. Greater error in dose quantification was apparent at the higher level although no statistical analyses could be performed due to insufficient data. However, there were some discrepant results. Results using other procedures, although only semi‐quantitative or qualitative, were in the correct order. Similar trials will be organized and will include a variety of food‐stuffs other than chicken.
Preparation of transparent pea protein gels: a comparison of isolation procedures
Authors: BACON J. R. , NOEL T. R. , LAMBERT N.
Published: July 2010

Two commercially viable procedures for the preparation of protein fractions from pea flour are described and discussed. These fractions form thermally induced transparent gels at acid pH and are composed of the globulins, vicilin and legumin, identified by electrophoresis and differential scanning calorimetry. The gels have clarities that allow their use as vegetarian substitutes for gelatin and additionally show thermal stabilities suitable for applications in hot products. The influence of other food ingredients (salt, sugar and vegetable oil) on gel clarity is also investigated.
Response of American consumers to akara, a traditional West African food made from cowpea paste
Authors: McWATTERS K. H. , RESURRECCION A. V. A. , FLETCHER S. M.
Published: July 2010

Dry cowpeas, an excellent source of protein and B‐vitamins, are underutilized in the US primarily because of their inconvenience. Akara, a popular West African food made from whipped cowpea paste that is seasoned and deep‐fat fried, has potential for extending use of cowpeas in US markets. Acceptance tests involving 450 respondents were conducted to assess response of US consumers to akara. Akara was most acceptable to Caucasians, older consumers, and those with no, little or some high school education. Its most appropriate use was perceived as a snack food with sauce and as a fully cooked, frozen, reheatable product.
Influence of precooking on the firmness and pectic substances of three stem vegetables
Authors: WU A. , CHANG W. H.
Published: July 2010

Edible portions of the stems of sprouting broccoli, asparagus lettuce, and large‐stem mustard were compared for total pectin contents, amounts of different pectin fractions, pectinesterase activities and changes during cooking to investigate effects on the textural changes during cooking. Slices precooked for 30min at temperatures below 60°C (broccoli) or 70°C (lettuce, mustard) were firmer after 15 min recooking in boiling water than those directly cooked without precooking. Optimum temperatures for this firming effect of precooking were 50, 60 and 60°C, respectively, and coincided with the optimum temperatures of activity of pectinesterases extracted from the fresh tissues. Analysis of pectin fractions revealed that the firming effect of precooking is related to the shift from the cold water‐soluble fraction to sodium hexametaphosphate‐soluble and hot water‐soluble fractions of pectins.
Extraction of ginger rhizome: partition constants and other equilibrium properties in organic solvents and in supercritical carbon dioxide
Authors: SPIRO M. , KANDIAH M.
Published: July 2010

Equations have been derived for the direct and indirect methods of determining partition constants for constituents extracted from food and other natural materials. A careful distinction is drawn between mass and volume partition constants. The direct method has been applied to the extraction of [6]‐gingerol from Jamaican ginger rhizome with supercritical carbon dioxide and the indirect method to its extraction with acetone, dichloromethane, ethanol and isopropanol. The resulting average mass partition constants were 0.29 and 0.39, respectively. The content of [6]‐gingerol in the original ginger rhizome was found to be 31–32μmol g−1. The extent of oleoresin extraction from the ground ginger and the degree of swelling and organic solvent uptake were also measured.
Mass transfer during osmotic dehydration of pineapple rings
Authors: BERISTAIN C. I. , AZUARA E. , CORTÉS R. , GARCIA H. S.
Published: July 2010

The effect of temperature (30, 40 and 50°C) and sucrose concentration (50, 60 and 70°Brix) on the osmotic dehydration of commercial size pineapple rings were studied, at an initial ratio of 1:4 fruit:sucrose solution. The rate of water loss in the fruit varied with both osmotic solution concentration and temperature. A proposed model based on Crank's equation was fitted to the experimental data.
An enzyme immunoassay for nisin
Authors: FALAHEE M. B. , ADAMS M. R. , DALE J. W. , MORRIS B. A.
Published: July 2010

The development of an enzyme‐linked immunosorbent assay (ELISA) for nisin using polyclonal antiserum is described. The method has a limit of detection of 1.9 X 10−2 i.u. ml−1 and correlates well with the bioassay. Its use in the analysis of commercial processed cheese samples is described and the results obtained compared with those from the bioassay.
Colour stability of thawed lamb chops. I. Effect of short‐term frozen storage
Authors: MOORE V. J.
Published: July 2010

The colour stability of thawed lamb chops was examined, by colour panel and colorimeter, under simulated retail display conditions. Chops held frozen at –20°C for 1 week had a display life of 3 days when thawed, compared with 2 days for fresh chops. When the frozen storage was increased to 8 weeks the display life was reduced to 1 day. When the whole loin was stored frozen for 8 weeks, chops cut from it and thawed had a 2‐day display life. By comparison, vacuum‐packed chops stored at –1.5°C for 8 weeks had a 3‐day display life. The relationship between Hunter colour values and panel scores is discussed.
Influence of sodium chloride and sodium tripolyphosphate on the quality of UK‐style grillsteaks: relationship to freezing point depression
Authors: SHEARD P. R. , JOLLEY P. D. , KATIB A. M. A. , ROBINSON J. M. , MORLEY M. J.
Published: July 2010

Grillsteaks were prepared from lean beef flaked at –4°C and subsequently mixed at nominal temperatures of either –3°C or +1°C with each combination of five sodium chloride levels (0, 0.5, 1.0, 2.0 and 4.0%) and three levels of sodium tripolyphosphate (Na5P3O10) (0, 0.25 and 0.50%).

Sodium chloride was more effective than sodium tripolyphosphate in lowering the initial freezing point (ifp) of meat, as measured by differential scanning calorimetry which also showed that the freezing point depression was proportional to the solute concentration.

Cooking losses generally were lower with higher levels of sodium chloride and sodium tripolyphosphate, and when the meat was mixed at +1°C. It is argued that localized salt concentrations can influence product quality, as can the relative proportions of ice and water when meat is processed below the ifp.
Effect of cooking and cooling method on the processing times, mass losses and bacterial condition of large meat Joints
Authors: BURFOOT D. , SELF K. P. , HUDSON W. R. , WILKINS T. J. , JAMES S. J.
Published: July 2010

This study compares the heating and cooling times of and mass losses from meat joints in three systems: convective air, water immersion and pressure/vacuum. Cooling times were compared with the UK Department of Health (DoH, 1989) guidelines which state that joints should be cooled to 10°C or below in less than 150 min.

Five types of joint were used: 50‐mm thick (0.94kg) slabs of beef m. semitendinosus, 2.7kg rolled beef forequarter and silverside, 6.4kg rolled turkey and 7.1kg boned‐out ham joints. Six replicates of all joints were cooked from 5 to 75°C (beef), 80°C (ham) or 85°C (turkey) and then cooled to a maximum internal temperature of 10°C.

Average cooking times for convection, immersion and pressure were 263, 278 and 135 min, respectively. Average cooling times for convection, immersion and vacuum were 433, 298 and 50 min, respectively. Vacuum cooling times did not depend on joint size but may have been affected by porosity of the meat. The DoH guidelines could be achieved by immersion or vacuum methods when cooling the small beef slabs but only vacuum cooling was sufficiently rapid when cooling the larger joints.

Mass losses due to pressure cooking (mean 37.4%) were greater than those during convection heating (28.9%). Vacuum cooling resulted in an average mass loss of 8.2% but losses were smaller after convection cooling (2.5%). Average total viable counts (log10 no. of bacteria cm−2) after processing and 12h storage were 1.0 at both the surface and interior.
Co‐trial on ESR identification and estimates of γ‐ray and electron absorbed doses given to meat and bones
Authors: DESROSIERS M. F. , McLAUGHLIN W. L. , SHEAHEN L. A. , DODD N. J. F. , LEA J. S. , EVANS J. C. , ROWLANDS C. C. , RAFFI J. J. , AGNEL J.‐P. L.
Published: July 2010

A multinational co‐trial was organized to determine if electron spin resonance (ESR) spectroscopy could be used to monitor foods exposed to ionizing radiation. The bones of chicken legs, frog legs and pork rib bones were prepared and distributed as unknowns to the participating laboratories. In every instance, non‐irradiated bones were correctly identified as such. Moreover, irradiated bones were not only correctly identified, but relatively good estimates of the absorbed dose were obtained. An intercomparison of the different approaches used by each laboratory is discussed, and recommendations for future trials are presented.