bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of aflatoxin M1 during manufacture and storage of yoghurt, yoghurt‐cheese and acidified milk
Authors: Hassanin Nagwa I
Published: November 2006

Yoghurt, yoghurt‐cheese and acidified milk were prepared from pasteurised half‐cream milk, naturally contaminated with aflatoxin M1 (AFM1) and then were stored at 4°C for 2 weeks. Levels of AFM1 in these dairy products were high, and then began to decrease during storage period at 4°C. Most of the AFM1 (recoveries of 71%) appeared in yoghurt‐cheese after 14 days, this is due to AFM1 being associated with casein fraction. Whereas pH values of yoghurt‐cheese during refrigerator storage ranged from 5.15 to 4.65 and titratable acidity ranged from 3.9 to 3.5 g lactic acid litre−1, whilst AFM, (recoveries of 41%) from yoghurt after manufacture and storage was much more susceptible to reduction by storage this is due to the higher acidity (range 2.3–3.1 g litre−1) of yoghurt by the action of microorganisms, besides the changes in pH values (5.10–4.70). When acidified milk was used the recoveries of toxin were 34.2% after 2 weeks; pH values ranged from 2.95 to 2.85 and titratable acidity ranged from 2.3 to 2.2 g litre−1 during storage.
Acid detergent dispersible lignin in tropical grasses
Authors: Lowry J Brian , Conlan Laurence L , Schlink Anthony C , McSweeney Christopher S
Published: November 2006

The detergent system of analysis partitions lignin into two fractions: acid detergent lignin (ADL), usually equated with forage lignin, and ‘acid detergent dispersible lignin’ (ADDL), the existence of which has scarcely been recognized, but can be higher than ADL in tropical grasses. For nine species ADL and ADDL as percentage of original dry matter were, respectively: Aristides calcyna. 8.9 and 9.8; Astrebla squarrosa, 8.6 and 14.7; Chloris gayana, 3.9 and 6.7; Eragrostis sp, 4.3 and 8.8; Heteropogon eontorius, 3.9 and 10.4; Iseilema membranaceum 7.2 and 8.2; Panicum maximum, 1.8 and 5.7; Themeda triandra, 7.3 and 8.2; Sorghum sp, 3.4 and 13.8. Tropical legumes (four species) had much lower levels of ADDL. Azo‐stained fibre showed that most of the free phenolic functions and the alkali‐soluble lignin were in the ADDL fraction. The difference between grasses and legumes was so marked that azo‐staining may provide a method for distinguishing grass and legume particles in feed or faecal samples. The apparent discrepancies between grasses and legumes in the effect of lignin on digestibility may be explained by the grass lignin having been grossly underestimated as ADL. When Heteropogon contortus and Astrebla squarrosa were incubated in dacron bags in the rumen the ratio of ADDL to ADL in the residual fibre decreased markedly in the first 48 h, indicating a higher apparent digestibility for ADDL. From feeding experiments with sheep the apparent digestibility of ADL and ADDL were 18 and 38% for Astrebia squarrosa and 14 and 26% for Stylosanthes hamata. As isolated lignin corresponding to ADDL was inhibitory in vitro to a mixed rumen microbial population at a concentration of 0.12 mg ml−1. Measurement of ADDL could easily be included in fibre analysis by the sequential detergent method as it would require only UV absorbance measurement on the acid detergent filtrate. This would allow measurement of total lignin within the existing system.
Relationship between the sensory properties of lupin seed with alkaloid and tannin content
Authors: Dupont M S , Muzquiz M , Estrella I , Fenwick G R , Price K R
Published: November 2006

Seven sensory characteristics (bitter, green, beany, metallic, astringent, floury and woody) were identified for a slurry of eight samples of milled lupin seed in water. This quantitative assay was applied to the seed of five species of lupin, which included three sweet and five bitter varieties. The levels of both total and individual alkaloids and of total tannin and catechin were determined by the chemical analysis of the seed and related to the sensory characteristics. A positive correlation was observed both between the bitter, metallic and woody tastes and between these tastes and total alkaloid content. Individual alkaloids, catechin and total tannin levels were not related to any of the sensory characters. Floury taste was inversely correlated to bitter, metallic and woody tastes, whilst astringent, green and beany tastes appeared to be independent of the other sensory characters.
Fermentation of orange processing wastes for citric acid production
Authors: Aravantinos‐Zafiris Gerasimos , Tzia Constantina , Oreopoulou Vassiliki , Thomopoulos Christos D
Published: November 2006

Press liquor from the dewatering of orange peel was used as a substrate for citric acid production. Of the three strains of Aspergillus niger examined, strain NRRL 599 produced the greatest amount of citric acid. The conditions favouring citric acid production were pH 5.0—6.2 in the presence of 40 ml kg−1 methanol. Under these conditions 30 g of citric acid per kg of press liquor were produced, representing a yield of 630 g kg−1 based on sugars consumed. The yield was further increased to 730 g kg−1 by thermal pretreatment of the press liquor.
Aflatoxin production by microorganisms of the Aspergillus flavus group in spices and the effect of irradiation
Authors: Ito Hitoshi , Ghen Hao , Bunnak Jintana
Published: November 2006

Aflatoxin production of Aspergillus parasiticus IFO 30179 and A flavus var columnaris S46 on black pepper, white pepper and red pepper was investigated and the results compared with those obtained using polished rice. The levels of aflatoxin B1 production on cooked and uncooked black pepper and white pepper were negligible. However, a little aflatoxin production was observed on red pepper even when uncooked. The inhibition of aflatoxin production was also observed in extracts of black pepper, white pepper and red pepper. Irradiation of the spices did not affect aflatoxin production.
The influence of variety and growth conditions on the nutritive value of carrots
Authors: Brunsgaard Grete , Kidmose Ulla , Sørensen Lis , Kaack K , Eggum B O
Published: November 2006

Three carrot varieties were cultivated under different growth conditions repeated over 2 years. A total of 35 samples, differing in variety (early, mid and late season type), total nitrogen supply (40–60 kg N per ha, 90–120 kg N per ha, 180–190 kg N per ha), time of harvest (early, mid and late) and cultivation year (1990 and 1991), were evaluated. The nutritive value of each of the 35 carrot samples was determined in trials with rats. Of the chemical components analysed, protein content exhibited the largest variation (46–101 g kg−1 DM). The late season variety had the highest protein content and the early season variety the lowest. The protein content increased with nitrogen fertilisation. The protein digestibility increased together with the protein content, probably due to a larger proportion of the protein being deposited as storage protein. The protein increment was accompanied by a significant drop in essential amino acids (g per 16 g N). The energy content was low (165–173 MJ kg−1 DM). However, the energy digestibility was high (76.2–88.8%) due to a large proportion of soluble fibre in the dietary fibre fraction. The content of Cd and Pb was below what is considered as acceptable levels.
Studies on the bitter principle and debittering of Palmyrah fruit pulp
Authors: Jansz Errol R , Nikawela Janaka K , Gooneratne Jaanaki , Theivendirarajah Kanagasabai
Published: November 2006

The main bitter principle of Palmyrah (Borassus flabellifer L) fruit pulp has been tentatively identified as a steroidal saponin which is tetraglycoside (flabelitferin II) containing two glucose and two rhamnose residues. Bitterness can be removed by the action of naringinase both on the crude bitter principle extracts (containing flabelliferins I and II) and natural fruit pulp. Naringinase released glucose and rhamnose to produce other flabelliferins, two of which occur naturally in palmyrah tuber.
Glucosinolates in etiolated sprouts of sea‐kale (Crambe maritima L)
Authors: Quinsac Alain , Charrier Anne , Ribaillier Daniel , Péron Jean‐Yves
Published: November 2006

Sea‐kale, a long‐forgotten vegetable, could make a resurgence due to its culinary attractiveness. Unfortunately, as with most cruciferous plants, its quality may be reduced owing to the presence of glucosinolates, mainly known for their antinutritional properties. The aim of this study was to evaluate the actual amount of these compounds found in edible sea‐kale sprouts, using qualitative and quantitative analysis by liquid chromatography carried out after treatment by freezing, blanching and cooking. Before treatment, the quantity of glucosinolates, of which more than 80% is represented by epi‐progoitrin, was found between 5.4 and 7.3 μmol g−1 of fresh matter. In this study, freezing then thawing causes a nearly complete decomposition of glucosinolates into nonidentified compounds which are most probably 5‐vinyloxazolidine‐2‐thionc and nitrites. Cooking for 4 min (blanching) brings about through leaching, a nearly 30% reduction. A greater decrease (76%) can be obtained with a cooking time of 20 min. The amount of glucosinolates found in sea‐kale was compared with that of other commonly used cruciferous vegetables and there appears to be practically no risk when consumed on a monthly basis. At present sea‐kale remains a desired vegetable in gastronomical dishes.
Quantifying transport phenomena in food processing with nuclear magnetic resonance imaging
Authors: McCarthy Michael J , McCarthy Kathryn L
Published: November 2006

Nuclear magnetic resonance imaging is a spectroscopic technique capable of measuring food structure and transport phenomena occurring in foods and in simulated process equipment. This review presents an introduction to the theory of nuclear magnetic resonance imaging and presents methods of analysis for quantifying the transport of heat, mass and momentum in foods during processing, lite methods demonstrate the utility of using nuclear magnetic resonance imaging to study food processing systems. Specific examples include characterization of the rheology of fluid foods and of liquid to solid phase transitions.
Cassava retting: Optimisation of a traditional fermentation by an experimental research methodology
Authors: Ampe Frédéric , Brauman Alain , Treche Serge , Agossou Aurelien
Published: November 2006

Retting, a spontaneous and traditional fermentation of cassava roots in Central Africa, was optimised in terms of time and the quality of the end‐product. Optimal conditions were achieved by using an experimental research methodology. Temperature is the most influential factor, with an optimum of 34°C for quicker retting. The roots should be peeled and soaked in water immediately after harvesting to increase the quality of cassava foods. Inoculation of water with juice from a prior retting helps in cassava detoxification but has no influence on the time or the quality of foo‐foo. Foo‐foo samples had the most favourable organoleptic quality when an incubation temperature of between 28 and 37°C was used. Using optimal conditions, retting time was reduced 3‐fold, and foo‐foo of high and constant quality could be processed.
Protein quality and energy density of green peas as influenced by seed size and time of harvest
Authors: Brunsgaard Grete , Kidmose Ulla , Kaack K , Eggum B O
Published: November 2006

Green peas (Pisum sativum L) were harvested at three different time points—3 days apart—and subsequently sorted into four fractions according to seed size (diameter > 10.2 mm; 10.2–8.75 mm; 8.75–8.2 mm and 8.2–6.0 mm). Three varieties from two years were investigated. The study comprised a total of 31 green pea samples. The average protein content of the samples was 276 g kg−1 DM with relatively low variation (SE = 5.7). Protein content was highest in the smallest seeds. The average energy content was 18.6 MJ kg−1DM. Dietary fibre content was 226 g kg−1 DM, the major part (77%) as insoluble fibre. Seeds of early harvest and seeds with the smallest diameter had the lowest fibre (IDF and TDF) content and at the same time the highest energy digestibility. The average energy digestibility was 83.2%. Protein digestibility was relatively high (average 92.1%), while biological value (BV) and net protein utilisation (NPU) were moderate to low (60.6% and 55.8% respectively) due to low contents of the essential amino acids (g per 16 g N), especially tryptophan, methionine + cystine and lysine. Contents of lysine, tryptophan and methionine + cystine were more than 20% higher in the smallest seeds compared to the larger seeds. Similar differences were observed in seeds of late harvest as compared with seeds of early harvest. Correlation coefficients revealed a strong positive correlation between lysine, tryptophan and methionine + cystine content and the biological value of green pea protein. The three varieties investigated showed no differences in the chemical parameters although small differences in BV and NPU were observed.
A comparative study of hesperetin and methyl anthranilate as markers of the floral origin of citrus honey
Authors: Ferreres Federico , Giner Josep M , Tomás‐Barberán Francisco A
Published: November 2006

Methyl anthranilate (MA) and hesperetin have been compared as markers for the floral origin of citrus honey. In the present work the contents of MA and hesperetin have been determined by GC and HPLC respectively in 18 honey samples produced in Mediterranean Spain. There was no correlation between the contents of MA and hesperetin. The concentration of MA ranged between 1.44 and 3.60 mg kg−1 while hesperetin ranged between 0.28 and 0.84 mg kg−1. These results support the hypothesis that hesperetin could be used as an additional marker in the determination of citrus honey origin.
Effects of ripening and parching on the quality characteristics, the chemical composition and the nutritive value of chickpea (Cicer arietinum L)
Authors: Attia Ramadan S , Shehata Ahmed M El‐Tabey , Aman Mohamed E , Hamza Mahmoud A
Published: November 2006

Physical properties and various chemical constituents of chickpea seeds were determined before and after ripening (malana and dry seeds of Giza 1 cultivar) and before and after parching (dry and parched seeds of Giza 2 cultivar). The raw dry seeds of Giza 2 were much smaller, lighter in mass and higher in seed coat percentage than those of Giza 1. Malana (green seeds at physiological maturity) seeds were large and uniform in size; they became smaller with much variation in seed size upon ripening. Parching significantly reduced the seed mass, but increased the seed volume. Marked differences in the chemical composition of the raw dry seeds were observed between the two cultivars which were grown under different environmental conditions. Ripening resulted in significant decreases in crude protein and polyphenol content but significant increases in nonreducing sugars, raffinose, neutral detergent fibre (NDF), add detergent fibre, cellulose, and phytic acid content. A considerable increase in Ca and Cu, a significant increase in in‐vitro protein digestibility, but significant reductions in NDF, trypsin inhibitor activity and phytic acid content occurred upon parching.
Evaluation, modification and comparison of two rapid assays for cyanogens in cassava
Authors: O'Brien Gerard M , Wheatley Christopher C , Iglesias Carlos , Poulter Nigel H
Published: November 2006

Two rapid semi‐quantitative assays for total cyanogens in cassava were evaluated. These were the well‐known rapid picrate paper test, and a recently proposed rapid paper test involving the reagent tetra base (TB, 4,4′‐ methylenebis‐(N, N‐dimethylaniline)). A precise colorimetric assay was used as a control in the evaluative work. After primary evaluation, both assay methods underwent some modification regarding the interpretation of sample scores. As a result, the reliability of the picrate assay was greatly improved. The TB assay was modified in the interests of safety. Evaluation of this assay over a range of temperatures between 20 and 35°C showed no significant temperature effects upon performance when the new scoring interpretation system was used. The level of endogenous linamarase activity in the sample was found to be an influential factor in rapid assay performance. In a series of comparative trials in three distinct ecosystems, the newly modified picrate assay produced correct results in 68% of cases. This compared with 66% of results correct in the TB assay. It was observed that the TB assay performed more reliably with low cyanogen samples, whilst the picrate assay was more reliable with intermediate cyanogen samples.
Aflatoxin and its metabolites in tissues from laying hens and broiler chickens fed a contaminated diet
Authors: Fernández Antonio , Verde M Teresa , Gascón Manuel , Ramos Juan José , Gómez José
Published: November 2006

Two groups of 32 hens and broiler chickens were contaminated with 2.5 and 5 mg of aflatoxin (AF) kg−1 feed for a period of 32 days. During this contamination 16 birds were sacrificed and aflatoxin and its metabolites were detected using thin‐layer chrotnatography and fluorescence densisometry. The tissues analysed (liver, muscle, kidney, gizzard and eggs) gave a wide range of concentrations, the lowest was found in ben muscle (0.05 μg kg−1 of AFB1) and the highest in gizzards from the 5 mg kg−1 group of the hens (9.01 μg kg−1 of AFB1). Metabolites of AFB1, AFM, and AFB2a appeared in the liver but not in other tissues. In broiler's tissues, the following metabolities were isolated: AFM1 and AFB2a, in liver, aflatoxicol in muscle and AFM1 and AFB2a in kidneys, all having concentrations lower than AFB1. Aflatoxicol was isolated from one egg sample (0.32 μg kg−1). For both types of birds, aflatoxin clearance time was only 24 h for muscle and kidneys. In livers from the 5 mg kg−1 group, AFM1 and AFB2a were still found 4 days after removal of the contaminated feed. In eggs and gizzards, aflatoxin residue was still detected on the 8th day of the clearance period although in low quantities. In the broiler's gizzards, clearance time was only 24 h. These results suggest that aflatoxin transfer to edible tissues is very small and the danger of contaminations to humans is also very small, except in the case of gizzards.
Release of ‘soluble’ lignin fragments from orchardgrass during its passage through the rumen
Authors: Kondo Tsuneo , Ohshita Tomoko , Kyuma Tadashi
Published: November 2006

Soluble lignin fractions were isolated with 90% (v/v) aqueous dioxane from the rumen digesta and faeces of a heifer fed on orchardgrass harvested at the pre‐heading stage. Chemical analysis, UV and IR spectra indicated that the soluble lignin fractions were composed mostly of lignin components. The two solube lignin fractions showed wide distributions of molecular weight and had number‐average molecular weights of 650–690 and weight‐average molecular weights of 1450–1480. The results showed that, part of the orchardgrass lignin fed was released in the rumen as soluble lignin fragments with different molecular weights and excreted in the faeces possibly without further significant modifications.
Influence of Yucca schidigera preparations on the activity of urease from Bacillus pasteurii
Authors: Killed Gerry F , Buggle Katherine A , Hynes Michael J , Walsh Gerard A , Power Ronan F , Headon Denis R
Published: November 2006

Extracts and preparations of the desert plant Yucca schidigera Roezl ex Ortgies (Mohave yucca), family Lillaceae, have a variety of beneficial effects when included in the diet of humans and domestic animals. Such effects include reduced gastrointestinal and faecal ammonia levels. A proposed mode of action is inhibition of microfloral urease (urea amidohydrolase; EC 3.5.1.5). We describe a rigorous method of in vitro urcase assay, in the presence of potential effectors such as Y schidigera preparations, using the phenolindophenol reaction to measure the ammonia product. The urease of Bacillus pasteurii was characterised in order to determine its suitability as a model bacterial urease. K‐phosphate, but not K‐HEPES or K‐citrate, was found to inhibit this bacterial urease, particularly at low pH, as previously reported for other plant and bacterial ureases. B pasteurii urease was found to have a Michaelis‐Menten constant, Km, of 10.5 ± 3.2 mM in 150 mM K‐HEPES, pH 65 and 0.89 M KCl, total ionic strength = 0.90 M at 30°C. It was therefore concluded that B pasteuriiurease is indeed a typical bacterial urease, suitable for studying the influence of Y schidigera preparations. For comparison, the effects of Y schidigera preparations on the activity of β‐galactosidase (β‐D‐galactoside galactohydrolase; EC 3.2.1.23) from Aspergillus or yzae, an unrelated hydrolase, were also determined. Urease and β‐galactosidase were both weakly and non‐specifically inhibited, in a fashion linearly related to the concentration of γ schidigera preparation. Linear regression of the relationship between γ schidigera preparation and enzyme activity yielded inhibition ratios of 3.2 ± 0.4 and 5.4 ± 1.6 nkat ml−1 preparation for urease and β‐galactosidase respectively. By comparing with reported in vivo rates of urea degradation in mammals it was concluded that the observed inhibitory properties of Y schidigera preparations are much too low to account for their in vivo effects at feed inclusion levels of as little as 100 g tonne−1.
Effects of pH, sulphur dioxide, alcohol content, temperature and storage time on colour composition of a young Portuguese red table wine
Authors: Dallas Constantinos , Laureano Olga
Published: November 2006

In a young Portuguese red table wine (Douro Valley) a significant relationship between the colour composition (anthocyanins, polymeric pigment, colour density) and five parameters (pH, SO2, alcohol, temperature, time of storage) were found. Higher temperature increased the loss of individual and total anthocyanins (as measured fay HPLC) during the ageing, while the wines with higher SO2 content contained a greater amount of anthocyanins. Malvidin 3‐glucoside acetate was the only anthocyanin not affected by the SO2 content, but its concentration was related with the interaction term (time of storage × SO2 content). Peonidin and malvidin 3‐glucoside‐p‐coumarate were the two anthocyanins affected by the quadratic term of temperature. Three different groups of equations corresponding to the three different states of the glucoside moiety were found. The polymeric pigment absorbance increases daring conservation and with higher temperature, while the pH and SO2 content decreased the polymeric pigment formation. The colour density of the experimental wine was related significantly to the changes of the coloured anthocyanins and to the polymeric pigment content.
Fatty acid‐containing lipids of the yeast Saccharomyces cerevisiae during post‐fermentation decline in viability
Authors: Slaughter J Colin , Minabe Masaharu
Published: November 2006

On exhaustion of the sugar supply in the medium, cells of the yeast Saccharomyces cerevisiae maintained at 30°C lost most of their phospholipid content and their viability, as assessed by methylene blue staining, within a few days. Both processes occurred more rapidly in cells which had fermented glucose rather than maltose. During this period of decline the cell content of other fatty acid esters, mainly t riacylglycerols, increased. This seemed greater in cells grown with maltose than with glucose but the latter cells also synthesised distinct amounts of waxes. The total quantity of lipid per cell did not change significantly during loss of viability although the composition of the lipid fraction did.
The effect of dietary α‐tocopherol supplementation and antioxidant spraying on colour stability and lipid oxidation of turkey meat
Authors: Sante Véronique S , Lacourt A
Published: November 2006

Vitamin E was supplemented in the diet (250 mg kg−1) of turkeys or sprayed directly on turkey meat. Turkey breast muscles were cut into 1.5 cm slices, wrapped with oxygen‐permeable film and stored at 2–4°C for 1 week. Colour coordinates (L*, a*, b*), pH and reflectance values between 630 and 580 nm were determined at various times post mortem, TBARS (thiobarbituric acid‐reactive substances) values and vitamin E content were assessed immediately after slaughter and at 7 days post mortem for vitamin E‐supplemented, sprayed and control groups. Vitamin E supplementation or antioxidant spraying resulted in a lower myoglobin oxidation (P < 0.05) and a higher a* value at day 2, but not thereafter. No differences in TBARS values and ultimate pH were detected. When peroxidation was induced experimentally by addition of an activated mixture, vitamin E supplemented or antioxidant‐sprayed samples exhibited lower TBARS values than the controls. Vitamin E supplementation in the diet or antioxidant spraying of meat produced a temporary delay in the rate of discoloration of turkey meat.
Effects of various surface treatments on the storage life of guava (Psidium guajava L) at 10°C
Authors: Mohamed Suhaila , Kyi Khin Ma Ma , Yusof Salmah
Published: November 2006

The use or various surface treatments to prolong storage life of guavas at 10°C was examined. LDPE shrinkwrap was most effective in reducing weight loss and maintaining the firmness of guava (most likely indicating its effectiveness in alleviating water stress), followed by clingwrap packaging and 200 g litre−1 palm oil emulsion coating. The skin colour of guava was most effectively preserved by LDPE packaging, sucrose‐ester and 200 g litre−1 palm oil emulsion dips. Paraffin treatment caused the skin to turn brown after 2 weeks storage. The ascorbic acid content was highest in control followed by clingwrapped guava. Clingwrapped guava also received the highest organoleptic scores followed by shrinkwrapping and 200 g litre−1 palm oil treated guava.
Immunoaffinity chromatography purification and characterisation of pea trypsin inhibitors
Authors: Frøkiaer Hanne , Hørlyck Lene , Sørensen Susanne , Sørensen Hilmer
Published: November 2006

Trypsin inhibitors from pea (Pisum sativum (L) cultivar Progreta grown in Denmark) have been isolated and shown to consist of at least nine pea proteinase inhibitors (PPI) with inhibitor activity toward both trypsin and chymotrypsin. The isoelectric points of the inhibitors were in the range 4.9–7.8. From this PPI mixture at least four inhibitors were isolated by immunoaflinity chromatography on a column containing immobilised monoclonal antibody (mAb) with inhibitor specificity. The PPI isolated by immunoaffinity chromatography were further separated by HPLC, and subsequent SDS‐PAGE analysis showed molecular weights for four of the PPI in the range 11.3–14.2 kD. Their pI were determined by isoelectric focusing, mAbs were used for immunochemical characterisation and their amino acid composition showed a high (14.7–21%) content of cysteine. Tryptophan was not present in any of the isolated PPI. The data now obtained support the resemblance of PPI with inhibitors of the Bowman‐Birk class and the differences in immunochemical properties of the various PPI indicate that pea has at least two gene loci coding for the inhibitors.
Flavour production in plant cell cultures of basmati rice (Oryza sativa L)
Authors: Suvarnalatha G , Narayan M S , Ravishankar G A , Venkataraman L V
Published: November 2006

Callus cultures of naturally flavoured rice (Oryza sativa var 370) called basmati were obtained on Murashige and Skoog medium with 2,4‐dichlorophenoxyacetic acid and kinetin. There was a perceptible basmati flavour in fresh callus. The volatile flavour components of basmati rice and callus were obtained by steam distillation‐solvent extraction and were analysed on GC‐MS. A qualitative comparison of volatile flavour components of callus cultures and natural basmati rice was also made. The results show the presence of 29 major compounds in rice and 23 in callus. The identified compounds include hydrocarbons, ketones, aldehydes, alcohols and esters. This demonstrated the potential of callus of basmati rice for flavour development.
Nutritional quality of yam (Dioscorea dumetorum and D rotundata) flours for growing rats
Authors: Lape I Mbome , Treche S
Published: November 2006

The digestibility and metabolism of diets based on flours prepared from raw, boiled or steamed tubers of the sweet yam (Dioscorea dumetorum) were evaluated in growing albino rats by the balance method in comparison with diets containing similar flours from the popular white yam (D rotundata). The results show that whatever their method of preparation, flours from D dumetorum promote higher growth rate and have higher nutritional value in the growing rat than corresponding D rotundata flours. This can be attributed to the good digestibility of D dumetorum starch which facilitates digestibility and absorption of nitrogen and other nutrients. Moisture‐heat treatment of tubers before processing into flour improves the nutritional value, especially for D rotundata.
Fermentation of cassava into foofoo: Effect of time and temperature on processing and storage quality
Authors: Blanshard Alex F J , Dahniya Mohamed T , Poulter Nigel H , Taylor Andrew J
Published: November 2006

The preparation and distribution of foofoo comprises several stages, namely soaking, dewatering and storage prior to sale. The effects of four different time/temperature soaking processes on the quality of foofoo (pH, microbial load, residual cyanogens) were determined. The processes were chosen as they gave roughly equivalent degrees of retting (the softening of cassava during soaking) by which the progress of the initial fermentation is normally judged. Instrumental measurement of cassava hardness confirmed that the processes were equivalent within experimental limits. The four soaking processes had no significant effect on the water content of foofoo, nor did this change during storage. Processing did affect the pH, total titratable acidity and microbial profiles. Analysis of the aqueous extracts from the processes showed that the glucose present in the fresh cassava was fermented into a mixture of acetic, butyric, isobutyric and lactic acids with some ethanol. The lowering of the pH reduced the number of Enterobacteriaceae to the limit of detection and also affected the types of microbe present. The different processes also affected the removal of cyanogens from the product and the processes at 20°C and 35°C led to unacceptable levels of cyanogens (mainly cyanohydrin) in foofoo.
Distribution of linamarin and its metabolising enzymes in cassava tissues
Authors: Nambisan Bala , Sundaresan S
Published: November 2006

The levels of the cyanoglucoside linamarin and the activity of its major metabolising enzymes (linamarase, rhodanase and β‐cyanoalanine synthase) were studied in various tissues of the cassava plant. Leaf, stem and rind tissues contained very high levels of both linamarin and linamarase, while lower levels were observed in edible tuber. Rhodanese activity was detected only in leaf tissue. High activity of β‐cyanoalanine synthase in all tissues indicated that the major pathway of cyanoglucoside turnover in cassava was by conversion to asparagine.
A physico‐chemical study of nigerian velvet tamarind (Dialium guineense L) fruit
Authors: Arogba Sunday S , Ajiboro Adejoke A , Odukwe Ifeanyi J
Published: November 2006

The edible part (pulp) of ripe Dialium guineense fruit is sweet (total sugars 582.1 g kg−1) but acidic (pH 3.3) and relatively poor in protein (61.3 g kg−1) and oil (700 g kg−1), Fairly low levels of ascorbic acid and tannin are present. The seed, however, is mildly acidic (pH 5.5), poor in oil (60.1 g kg−1) but a fairly good source of protein (148.8 g kg−1) and minerals.
The influence of metal ions on concentrations of flavour‐active sulphur compounds measured in beer using dynamic headspace sampling
Authors: Walker Martin D
Published: November 2006

Addition of copper(II) ions (≤1.6 mg litre−1) to beer significantly reduced (P ≤ 0.05) concentrations of hydrogen sulphide and ethanethiol measured in beer, but had no effect on methyl sulphide, methyl thioacetate and methyl disulphide. Zinc, iron(III), manganese(II), nickel, lead(II) and tin(II) ions, at similar concentrations, had no effect on any of the sulphur volatiles. When metal ions were added at a concentration of 1 glitre−1 zinc, iron(III) and lead(II) reversibly bound hydrogen sulphide and enthanethiol.
Sensory characterisation of virgin olive oil and relationship with headspace composition
Authors: Servili Maurizio , Conner John M , Piggott John R , Withers Stephanie J , Paterson Alistair
Published: November 2006

Thirty samples of virgin olive oil were analysed by sensory and instrumental methods. Free‐choice profiling and quantitative descriptive analysis were used for odour analysis, and GC‐MS for the analysis of headspace volatiles. Principal component analysis and partial least squares regression analysis were used for relating sensory and instrumental data. Similar clusters of samples were obtained from principal components analyses of both data sets. Partial least squares regression made good predictions from headspace data of some of the descriptors used in quantitative descriptive analysis. The prediction of cut grass odour was obtained in particular from five unidentified compounds. The five compounds had similar mass spectra, but GC‐sniffport analysis showed that only one of them (possibly isomers or homologues) gave an aroma that could be related to the cut grass descriptor.
Determination of the geographical origin of wine using joint analysis of elemental and isotopic composition. II—Differentiation of the principal production zones in france for the 1990 vintage
Authors: Day Martin P , Zhang Benli , Martin Gerard J
Published: November 2006

Stable isotope analysis of grape juices and fermented products involving 2H‐NMR spectroscopy and isotope ratio mass spectroscopy was carried out in combination with elemental determinations performed by atomic absorption spectroscopy using flame and thermal ionisation. One hundred and sixty five grape samples were carefully collected in well‐defined vineyards of France situated in Alsace, Burgundy, Beaujolais and the Loire Valley. Moreover, the samples from Burgundy were picked from four typical Appellations (Cǒtes de Nuits, Cǒtes de Beaune, Cǒtes Chalonnaises and Mǎconnais) in order to ‘zoom’ the approach to smaller production areas. An exhaustive statistical evaluation of the 165 ± 16 data set was carried out by analysis of variance and principal component analysis. To conclude this study, the classification of the samples in typical Appellations was carried out by discriminant analysis with a nearly 100% degree of achievement.
Effect of stabilisation treatment of rice bran on functional properties of protein concentrates
Authors: Prakash Jamuna , Ramanatham G
Published: November 2006

The functional properties of differently dried protein concentrates prepared from unstabilised, acid‐stabilised, heat‐stabilised and parboiled rice bran were evaluated. Freeze‐dried protein concentrates from all types of bran exhibited similar nitrogen solubilities. Both cabinet‐and roller‐dried protein concentrates had lower nitrogen solubilities than freeze‐dried samples except for cabinet‐dried concentrate from heat‐stabilised bran. The functional properties (bulk density, water and fat absorption, emulsification and foaming capacity) of protein concentrates prepared from acid‐stabilised rice bran were not significantly different from those prepared from untreated bran. Freeze‐dried protein concentrates from both heat‐stabilised and parboiled rice bran had low water absorption capacity and high fat absorption capacity. Cabinet‐dried samples did not exhibit any foaming or emulsification capacity, thereby indicating a greater extent of denaturation. Thus, the study indicated that in addition to stabilisation treatment functionality was also influenced by the drying technique employed.
A quality comparison of breads baked by conventional versus nonconventional ovens: A review
Authors: Yin Y , Walker C E
Published: November 2006

Undesirable qualities of breads baked in nonconventional ovens have been observed by most researchers. The altered heat and mass transfer patterns and much shorter baking times associated with microwave radiation resulted in a crustless product with tougher, coarser, but less firm texture. Insufficient starch gelatinization, microwave‐induced gluten changes, and rapidly generated gas and steam caused by the heating mode could be reasons for quality changes in the microwave‐baked breads. Although breads baked in an electrical resistance oven did not brown, their interior characteristics and shelf‐life were superior to those of products baked in a conventional oven. Bread with a superior keeping quality was obtained using an air impingement convection oven. The determination and explanation of the physical and biochemical changes that occur in products during baking in conventional versus nonconventional ovens are fruitful areas for future research.
Effect of urea and by‐products on the in‐vitro fermentation of untreated and urea treated finger millet (Eleusine coracana) straw
Authors: Sampath Koratikere T , Wood Christopher D , Prasad Cadaba S
Published: November 2006

The in‐vitro fermentation characteristics of untreated and 50 g litre−1 urea‐treated finger millet (Eleusine coracana) straw with four supplements (urea, rice bran, cottonseed and groundnut cakes) at three different ratios of straw: supplement were investigated. Gas production was greater from treated than untreated straw; groundnut cake was the most rapidly fermented supplement followed by cottonseed cake and rice bran. Urea incubated alone inhibited gas production. Untreated and treated straws were incubated with 22, 30 and 37 g rumen degradable nitrogen from the supplements per kg organic matter digested. Significant (P < 0.05) positive interactive effects on gas production were observed with untreated straw at all three levels of groundnut cake supplementation after 12, 52 and 166 h incubation. Similar interactions were observed for cottonseed cake supplementation of untreated straw and groundnut cake supplementation of treated straw, although statistical significance was not achieved for all supplementation levels at the three times for which data were analysed. No consistent significant interactive effects in gas production were observed between cottonseed cake and treated straw. Rice bran inhibited gas production after 12 h but, subsequently, had little effect on either type of straw. Urea inhibited the gas production from both straws at all three ratios of supplementation. Urea also significantly reduced dry matter disappearance of treated straw at two of three levels of urea supplementation. Interactive effects on gas production were most pronounced in the early stages fermentation and appeared to be related to the high content of highly fermentable material particularly in groundnut cake but also in cottonseed cake.
Antioxidative activity and scavenging effects on active oxygen of xylose‐lysine maillard reaction products
Authors: Yen Gow‐Chin , Hsieh Ping‐Ping
Published: November 2006

The antioxidative activity and scavenging effects on active oxygen of Maillard reaction products (MRP) prepared by heating xylose and lysine (XL) at a molar ratio 1:2 and pH 9.0 for 1.5 h (XL‐1 to XL‐5) were investigated. The antioxidative activity and browning intensity of XL MRP increased with increasing duration of reaction, but XL‐1 and XL‐2 MRP showed greater reducing power than other samples (P < 0.05). All XL MRP showed scavenging activity on 1,1‐diphenyl–2‐picrylhydrazyl (DPPH) radical. XL‐1, XL‐2 and XL‐3 MRP exhibited about 50% reduction in absorbance of superoxide. Scavenging effects of XL MRP on DPPH radical and superoxide were markedly decreased after decolorization with Sep‐Pak Cartridge C18, indicating that the browning pigment might contain components that can scavenge superoxide or donate hydrogen atoms. The electron paramagnetic resonance spectra indicated that XL MRP had scavenging activity on the hydroxyl radical; this scavenging effect depended on dose (r = 0.99) and increased with increasing duration of reaction. Based on these data, the antioxidative activity of XL MRP may be attributed to the combined effects of reducing power, donation of hydrogen atoms and scavenging of active oxygen.
Mid‐infrared spectroscopy and chemometrics for determining the type of fruit used in jam
Authors: Defernez Marianne , Wilson Reginald H
Published: November 2006

Fourier transform infrared spectra of jams were analysed by chemometric methods with the aim of differentiating between ‘strawberry’ and ‘non‐strawberry’ containing jams. Spectra were subjected to a data reduction step, which was either principal component analysis (PCA)‐based or partial least squares (PLS)‐based, before being classified in one of the two jam types on the basis of the smaller distance to the group ‘means’. Diffuse reflectance infrared spectra of the insoluble materials of the jams led to a success in classification of almost 100%. However, the preparation method was lengthy and still needs some improvement. Attenuated total reflectance spectra of jams were classified according to fruit type with 91% success. This method was found to be strongly influenced by the spectral differences between ‘normal’ and ‘reduced’ total sugar content jams, which appeared in the first principal component in both the PCA‐based and the PLS‐based method.
Lipid oxidation in salted‐dried fish: II. The effect of photosensitisers on the rate of oxidation of a fish oil
Authors: Davis Louise , Smith Gillian , Hole Michael
Published: November 2006

The contribution of photosensitised oxidation to the extent of lipid oxidation of a model fish oil system has been considered using a number of methods of measurement, namely peroxide value, polyene index and the initial rate of oxygen uptake. This represents the initial stages of the development of a model system which will eventually simulate the processing and storage of salted, sun‐dried fish. The effects of the photosensitisers, protoporphyrin IX, riboflavin and myoglobin on the rate of oxidation of a highly unsaturated fish oil in a model system, have been studied under dark or photosynthetic light conditions at 30°C. As has previously been established, the initial rate of oxygen uptake proved to be a more reliable method than the peroxide value or the polyene index in determining the extent of lipid oxidation of the oil in the model system. Protoporphyrin IX, riboflavin and myoglobin all increased the rate of oxygen uptake significantly in photosynthetic light at 30°C, from a rate of 0–158 μl O2g−1for the control to 0.335 μl O2g−1min−1, 0.308 μl O2 g−1min−1 and 0.461 μl O2g−1min−1, respectively. However, in the dark at 30°C their addition had no effect on the initial rate of oxygen uptake, showing that these components increased the rate via a photosensitised oxidation mechanism rather than by autoxidation. The addition of β‐carotene, a well‐established singlet oxygen quencher, to the systems containing the photosensitisers at 30°C in the light significantly reduced the rate of oxygen uptake, but not to the same rate as in the control. Photosensitised oxidation has been classified as Type I or Type II; the reduction observed in oxygen uptake rate in the presence of β‐carotene shows the Type II mechanism involving singled oxygen to be important. Studying β‐carotene on its own in the model system at 30°C showed an unexpected increase in the rate of oxygen uptake both in the light and in the dark.
Effect of phytate on the in‐vitro solubility of Al+, Ca2+, Hg2+ and Pb2+ as a function of pH at 37°C
Authors: Bullock Joseph I , Duffin Paul A , Nolan Kevin B , Smith Terence K
Published: November 2006

The effect of phytate on the solubility of Al3+ and Pb2 + has been investigated in vitro at 37°C across the pH ranges 3–7 (Pb2+) and 2–5 (Al3+). For both ions minimum solubility was found when the initial metal ion: phytate ratio was in the range 5:1–3:1 across the whole pH range. For Al3+ the solubility rose sharply either side of these ratios whereas for Pb2 + solubility rose only slowly as the metal ion: phytate ratio was reduced. Hg2+ was totally soluble under all conditions tested. At pH 7 Ca2+ solubility was found to be at a minimum when the initial Ca : phytate ratio was 5 :1 irrespective of the initial Ca2+ concentration.
The production of recombinant proteins in plants
Authors: Whitelam Garry C
Published: November 2006

For recombinant proteins that are required in large quantities, plant agriculture probably represents the most cost‐effective means of production. However, the absence of efficient methods for the processing of harvested plant materials and for the cost‐effective purification of extracted proteins has so far limited the exploitation of plant expression systems. This problem, which is particularly acute for recombinant proteins required at high purity, is now being addressed. Thus, the application of oleosins as carrier proteins may provide a facile means of separating recombinant proteins from bulk seed proteins. Transgenic plants are being assessed for the production of a number of recombinant industrial enzymes. Significantly, the seeds from transgenic plants expressing genes encoding either phytase or α‐amylase can be more or less directly employed as enzyme formulations for poultry feed modification and for starch liquefaction, respectively. Furthermore, transgenic seeds provide a simple means of storing and transporting recombinant enzymes. The plant‐synthesised phytase and α‐amylase enzyme are active despite displaying non‐native patterns of glycosylation. Transgenic plants have been shown to be capable of synthesising a wide range of recombinant antibodies and antibody fragments that are typical of those used in industrial processes and in therapy. Plants may be particularly suited to the production of complex, multimeric immunoglobulins since genes encoding the different components of these complex molecules can be combined by simple sexual crossing of individual transgenic plants.
Use of Porter's reagents for the characterisation of thearubigins and other non‐proanthocyanidins
Authors: Powell Christopher , Clifford Michael N , Opie Shaun C , Gibson Colin L
Published: November 2006

A previously published method for the HPLC analysis of the anthocyanidin pigments produced by the autoxidative depolymerization of proanthocyanidins by heating in a solution of n‐butanol/HCl (95/5 v/v) and iron(III) salts (Porter's reagents) has been refined. The pigments are detected by monitoring at 530 nm, but by monitoring the eluate also at 280 nm and 380 nm a wider variety of products resulting from the same autoxidation and/or hydrolysis/transesterification reactions can be detected. Such products have been shown to include aglycones (particularly flavonols from flavonol glycosides) and n‐butyl gallate (from galloyl esters). The advantages of monitoring the wider range of transformation products are illustrated by applying the method to the characterisation of two heterogeneous thearubigin fractions isolated from black tea liquor. The caffeine‐precipitatable thearubigin fraction contained 181 g proanthocyanidins kg−1 (as procyanidin dimer equivalents), a trace (∼2 g kg−1) of flavonols (as aglycones), 74 g kg−1 galloyl ester and 5·6 g kg−1 elemental N (determined by microanalysis): caffeine was not detectable and some 74% of the fraction remains uncharacterised. The theafulvin fraction contained 105 g proanthocyanidins kg−1 (as procyanidin dimer equivalents), < 1 g kg−1 quercetin and 71 g kg−1 galloyl ester, but neither caffeine nor elemental N was detectable; some 82% of the fraction remains uncharacterised. The proanthocyanidins of both hump fractions contained not only prodelphinidins and procyanidins but also propelargonidins which have not previously been reported in tea.