摘要:

ABSTRACTAn intermediate moisture model food system containing casein, glucose, glycerol, oil, microcrystalline cellulose and water, was used to study nonenzymatic browning. The initial molar ratio of glucose to available lysine was varied from one‐half to five. The model food system samples were prepared to 0.52 water activity and were stored in sealed cans at 45°C and analyzed periodically. The browning was followed by determining pigment accumulation, glucose utilization, and loss in FDNB‐available lysine. The rate of pigment formation followed zero order kinetics after an initial short induction period. This rate increased linearly as the initial molar ratio of glucose to available lysine increased from one‐half to three. Above this ratio the rate did not change. The initial rate of glucose utilization and available lysine loss obeyed first order kinetics, and increased as the initial molar ratio of glucose to available lysine increased from one‐half to five. This work shows that in the presence of glycerol, the initial condensation reaction is not the rate controlling step for pigment pr

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1976.tb14372.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTA multilayer adsorption equation, originally developed for physical adsorption on nonuniform surfaces, is used to describe the water sorption behavior of a great variety of foods and food components. Characteristic parameters of the sorption equation, for each of the products tested, were computed. A comparison was made between Halsey's equation and Henderson's classical one. Literature data for 220 food isotherms, comprising 69 different materials, were utilized to compare both equations. It was found that in most cases Halsey's equation has a better fit than Henderson's.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1976.tb14373.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTA series of kinetic experiments with aqueous ozone solutions showed that the equation, n co‐ n c = kt, was approximately linear over a period of several hours. The straight‐line segment of this function was extrapolated to 0 hr, and the slope for each extrapolated straight line, representing k, was derived. It was then possible to calculate residual concentrations (c) from corrected covalues. Fifty such calculations resulted in an average of 55% retention of ozone concentration in the upper solubillty range at the end of the first hour. This residue required more than 8 hr for complete disappearance. There was a significant increase in ozone concentration upon small additions of acetic acid to water. In contrast, sodium chloride at a certain concentration accelerated the loss of ozone from solut

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1976.tb14374.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTThe efficiency of a urea‐acid system as an extraction medium for riboflavin from a wide variety of food products was evaluated. Riboflavin present in hamburger and pork was extracted with urea and 1N HCI acid solution. Fruits and all ofher food samples selected for this study, required urea in the presence of 0.lN H2SO4and 0.2N H2SO4acid solutions respectively for the extraction of riboflavin. The extracts were diluted to a known volume, filtered and analyzed. The blank readings of the samples were determined by reducing riboflavin to a nonfluorescent compound with sodium hydrosulfite solution. The analytical data obtained for riboflavin was compared with results obtained by AOAC, enzymatic‐hydrolysis methods and literature values. Automated results were lower for meat and dairy products but higher for fruits and vegetables in comparison with the AOAC values. In general, the suitability of urea‐acid system for the extraction of riboflavin from a wide variety of food products was comparable to those of AOAC and enzymatic‐hydrolysis methods of ext

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1976.tb14375.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTQuality audit data collected as part of a mass feeding quality assurance program were analyzed to determine the relationships between the indicator tests (total aerobic plate count, coliform count andEscherichiu coli) and the common food‐borne pathogens (Staphylococcus aureus, Clostridium perfringensandSalmonella). 132 raw foods and 593 ready‐to‐eat foods were evaluated. The indicators were grouped into ranges and compared to the pathogens and to each other in terms of detectability. There were correlations between the pathogens and the indicator ranges and between the indicators and the indicator ranges. The value of the indicators in the èvaluation of food safety was tested by setting standards and determining the numbers of correct and incorrect decisions which would be made relative to the pathogens detected in the foods. None of the indicators was suitable as a screening agent for food

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1976.tb14376.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTActual amounts of octanal, decanal, dodecanal, tetradecanal, geranial and neral in various coldpressed citrus oils were determined by quantitatively preparing and analyzing the 2,4‐dinitrophenylhydrazone derivatives. These major and other minor carbonyl components in citrus oils were separated and isolated using a combination of column and thin‐layer chromatography of the derivatives. Differences in aldehyde composition include nearly equal amounts of octanal and decanal in Valencia orange oil and significantly less decanal than octanal in Pineapple, Hamlin and Temple orange oil. Tangerine oil has nearly equal amounts of octanal and decanal, but lesser quantities than the orange oils. Valencia essence oil, manufactured commercially by decantation from the aqueous essence phase recovered during juice evaporation, contained almost twice as much decanal as octanal. Coldpressed oils generally showed higher aldehyde/ester ratios than essence oils. The higher ester contents of the essence oils accounted for a more juice‐like aroma of the latter. Quantitative chemical analyses of total aldehydes, esters, alcohols and acids of eight types of citrus oils were performed. These analyses illustrated basic compositional differences in the oxygenated components of orange, mandarin, grapefruit and essence

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1976.tb14377.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTThe degree of browning produced from the oxidation of 4‐methyl catechol by Lerman and Fuerte avocado PPO was affected by the presence of various phenol‐type compounds which could not, by themselves, act as substrates for the enzyme.P‐coumaric acid, protocatechuic acid and p‐cresol arrested the development of dark‐colored o‐quinones, while phloroglucinol, orcinol and resorcinol markedly increased their formation. Similar relative effects were obtained with PPO of either avo

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1976.tb14378.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTInactivation of poliovirus with strawberry extract was time and concentration dependent and could be prevented or reduced but not reversed with serum or gelatin. Strawberry extract inactivated several enteric viruses and herpes simplex virus, and extracts of several fruits inactivated poliovirus; the degree of activity varied with the virus type and the fruit species showing a minimum two log reduction with undiluted fruit extracts, adjusted to pH 7.0. Step‐wise ultrafiltration of strawberry extract indicated that activity was found in fractions of molecular weight300.000. Several compoinds of plant origin were’ found to be antiviral; tannic acid was especially potent. Treatment of HEp2 cells with strawberry extract or tannic acid reduced subsequent infection with virus, almost a log; inhibition was prevented and reversed completely with serum or gelatin. The antiviral components of various fruits and plants may act both on viruses and host cells to prevent in

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1976.tb14379.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTWhen stored at room temperature in the dark, neither peroxide nor total carbonyls rose in raw lightly‐milled rice during 3 yr but parboiled rice became rancid in a few months. The rate of autoxidation was greatly increased when the samples were stored in thin layers in open dishes at a high temperature, but the effect of temperature was greater in raw rice than in parboiled rice. Exposure to light hastened the autoxidation in raw rice at room temperature; it had relatively less effect in parboiled rice or at a high temperature. A high (normal) moisture content delayed the onset of oxidation in lightly‐milled parboiled rice and delayed as well as suppressed it in raw rice, and vice versa. Surprisingly powdered raw rice autoxidized nearly as fast and as much as parboiled whole rice; but in parboiled rice grinding had only a moderate effect. The degree of milling had a dramatic effect on the autoxidation process in raw rice: unmilled rice was very stable, but the rate of oxidation increased sharply with increasing milling. In contrast, the degree of milling had little effect in parboiled rice. The reported presence of antioxidants in raw rice and their destruction in parboiled rice as well as the changed disposition of fat in the latter seem to be implicated with these resu

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1976.tb14380.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTBarley was steeped, malted, and kilned under laboratory conditions. Surface structures of sections were examined by scanning electron microscopy and mineral element components were measured by X‐ray microanalysis. Cell walls and grains of aleurone cells increased in size as a result of steeping and their structures changed throughout the subsequent malting process. In the center of the starchy endosperm, there was an extensive breakdown of the protein matrix, degradation of cell walls, and little degradation of large starch granules. Concentrations of most minerals were lower in steeped than in unsteeped barley, and continued to decrease throughout the malting process. Whereas mineral concentration changes in the husks and pericarp were minor, large decreases were noted in the aleurone tissues. Movements of mineral elements from aleurone grains to the starchy endosperm were slower for Ca and Mg than for P and

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1976.tb14381.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY