摘要:

ABSTRACTThe problem of migration from a packaging material into packaged food is treated in the literature using extraction studies from polymeric materials into simulating solvents such as heptane, oil, water, 3% acetic acid, 50% ethanol, etc. (Figge, 1972). Such studies provide a good measure for predicting possible migration into foods, but do not serve as a direct measure for the relative affinity of foods or their components for the migrant (e.g. vinylchloride monomer, VCM). The approach taken in this study was to establish directly the relative affinities of the basic food constituents for vinyl‐chloride. Sorption measurements of VCM by four basic food constituents, (water, corn oil, casein and sucrose) were conducted. In addition, sorption studies were carried out with oil in water emulsions. For water, oil, oil/water emulsions and casein, it was found that the partition coefficient values (defined as the equilibrium concentration of VCM sorbed over the equilibrium concentration of VCM in headspace) were fairly constant within the sorbate (VCM) concentrations studied. At 24°C, the partition coefficient values for oil, casein and water were 23.7 × 103, 11.7 × l03and 2.1 × 103, respectively. Sucrose did not sorb detectable amounts of VCM under the experimental conditions employed. The sorption of VCM by an oil‐in‐water emulsion, representing a multi‐component system, follows the same relationship to initial headspace concentration and temperature as do water and oil. The total amount of VCM sorbed by the emulsion, however, is not the exact arithematical sum of potential contributions of its individual components. Sorption studies showed that the chemical nature of the sorbent (i.e. food constituent), starting sorbate (i.e. VCM) concentrations and temperature are important factors affecting the extent of vinylchlori

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1979.tb10002.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

ABSTRACTSorption of vinylchloride (VCM) by dry casein particles was determined as a function of temperature and moisture content. The amount sorbed was found to increase with a decrease in temperature or reduction in moisture content of the particles. At 30° C, the partition coefficient values (Ku) were 1.05, 0.4 and 0.33 × 102for casein particles of moisture content 3.5, 6.0 and 7.5, weight percent respectively. The partition coefficient was defined as the equilibrium concentration of VCM sorbed over the sorbate concentration in the headspace. The effect of dipole moment of the sorbate on sorption to casein was evaluated by comparing sorption of VCM and the analogues, ethylene and vinylidene chloride. Sorption was found to increase with the dipole moment of the sorbate, suggesting the importance of dipole moment as a sorption inducing factor. Further supportive evidence for the importance of dipole moment in sorbate‐casein interaction was obtained by a gas chromatographic technique (inverse phase gas chromatography). Using casein as the stationary phase of a gas chromatographic column, the solutes VCM, ethylene, vinylidene chloride (VCD) and hexane were pulsed through the column and the peak shapes recorded. Peak shapes indicated an interaction between casein and the polar solutes (VCM and VDC) whereas no such interaction (sorption) was indicated for the nonpolar solutes, ethylene and hexane. A rate model for VCM sorption by dry casein particles was also develo

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1979.tb10003.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

ABSTRACTCoconut protein prepared from fresh coconut kernels has been studied and was found to separate into at least three protein peaks in column chromatography, and six protein bands in electrophoresis. The protein solubilized maximally at pH 10.3 and precipitated at pH 5.8. It was found to be associated with lipid in a 10:1 ratio. Analysis of its enzyme activities showed that it has five at pH 6.3, the natural pH for the coconut fruits. Esterase and lipase activities were absent in the mature fruits while pyrophosphatase and acid phosphatase activities were high. Possible roles of the protein in the metabolism of the coconut fruits are discussed.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1979.tb10004.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

ABSTRACTComplex formation of anthocyanins with rutin stabilize their color under conditions similar to those of grape juices. This color intensification results in both the increase in intensity and a batho‐chromic shift in the color of their solutions. The changes in the color intensity of the anthocyanin solutions are not uniform throughout the pH range 1–7, but are influenced by the substitution patterns of the B‐ring, and by the nature of substituent in the 3‐ and 5‐position. Thus maximum complex formation occurs with the 3‐glucosides at around pH 4.2, with the 3,5‐diglucoside at around pH 3.1, with the 3‐acylglucosides around pH 4.0–4.5 and at around pH 3.1 with the 3‐acylglucoside+glucosides: The obtained data further support the involvement of the anhydro base of anthocyanins in the complex formation with rutin

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1979.tb10005.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

ABSTRACTFive citrus methoxy flavones that have been found to have physiological activities on human erythrocyte can be separated and determined quantitatively by HPLC. Tangerine juice was found to have more nobiletin and tangeretin but lower amounts of the other three known flavones than orange juice. Several other peaks remain to be identified. Characteristic patterns of these juice flavones may be used to determine the presence of one juice in the other.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1979.tb10006.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

ABSTRACTThe rate of betanine degradation as affected by monocarboxylic acids (lactic acid, acetic acid), metal cations (Fe+++, Cu++), antioxidants (ascorbic acid, α‐tocopherol) and sequestrants (citric acid, Na2EDTA) was studied. Betanine was extracted from beets using water, and purified by molecular exclusion and adsorption chromatography. Column packings used were Sephadex G‐25, polyacrylamide, and polyvinylpolypyrrolidone. The effect of food additives on the rate of oxidation of betanine in buffered systems was determined using a modification of the active oxygen method. A betanine solution was placed in a reaction chamber, held at 75° C, and oxygen was passed through the solution at a rate of 3 ml/min. The half‐life value of betanine at 75° C, pH 5.0 in a phosphate buffer was 48.0 ± 1.0 min (control). Addition of 100 ppm lactic acid had no effect on stability (41 ± 1.7 mm), while 5.9% acetic acid caused a decrease in stability (33.4 ± 1.9 min) possibly as a result of pH changes at elevated temperatures. Metal ions at a level of 100 ppm caused an increase in the degradation rate compared to that of the control with addition of iron resulting in a half‐life value of 33 ± 1.4 min. Copper had the greatest effect, reducing the half‐life value to 6.0 ± 0.2 mm. Neither 100 ppm ascorbic acid nor 100 ppm a‐tocopherol affected the half‐life value of betanine (45.3 ± 2.3 and 50.2 ± 3.4 min, respectively). Ascorbic acid at 1000 ppm decreased the halt‐life value (32.3 ± 3.3 min), whereas 10,000 ppm citric acid and 10,000 ppm EDTA caused an increase in the half‐life value of 1.5 times compared to that of the control (69.4 ± 3.1 and 70.7 ± 7.1 min). Both 100 and 1000 ppm citric acid had n

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1979.tb10007.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

ABSTRACTFactors responsible for the differences in color quality between preserves commercially manufactured from Hood and Tioga strawberry varieties were determined. Color analyses on Hood and Tioga preserves during a 26‐wk storage period revealed that color deterioration occurred at a much faster rate in Tioga preserves than in Hood preserves, and that this deterioration was due to a faster rate of browning. Compositional analyses of fruit showed that the Tioga variety contained higher levels of leucoanthocyanins, flavanols and total phenolics while the Hood variety contained higher levels of anthocyanin pigment, ascorbic acid, and free amino acids. It is proposed that reactive phenolics (leucoanthocyanins, flavanols) play a major role in the color deterioration of strawberry preserve

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1979.tb10008.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

ABSTRACTA selected panel was used to determine the odor threshold of geosmin [trans‐1, 10‐dimethyl‐trans‐(9)decalol], an important aroma constituent of table beets, in juice made from cooked and peeled beets. The estimated threshold of 5.8 parts geosmin in 109parts beet juice was 35 times higher than the odor threshold of geosmin in water determined by the same panel. Four samples of cooked beet juice containing different levels of geosmin were subsequently ranked according to their characteristic beet‐like aroma. An increase in geosmin content was perceived as an increase in beet‐like aroma up to a 5.8 ng/g concentration of geosmin. Juice made from cooked and peeled beets showed a 56–60% reduction in geosmin content in comparison with juice prepared from raw beets (with geosmin concentration below 5.8 ng/g). Therefore processing may reduce the characteristic a

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1979.tb10009.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

ABSTRACTTable beet polyphenol oxidase (PPO) causes undesirable color in underblanched products. The effects of pH and temperature on PPO activity were studied. Varietal differences and the effects of blanching on PPO activity of table beets were measured. The enzyme was most active at pH 7.0 and temperature 25°C. The rate of heat inactivation increases rapidly with increasing temperature and follows pseudo‐first order kinetics. The enzyme activity varied among different cultivars of table beets. Water blanching deactivated the enzyme but the time required for a complete inactivation varied according to the size of table bee

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1979.tb10010.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

ABSTRACTMost stability studies on carotenoid pigments and vitamins A in food systems concern autoxidation only. Trans‐cis isomerization of all‐trans lycopene (ATL) during tomato processing, and subsequent reversion in storage, lead to different sequence. Proposed reaction pathway scheme, based on known isomer characteristics and constituent reactions, includes lycopene autoxidation/isomerization relationships. The pathway may be applicable more generally to carotenoid degradation in other foods. Stage I: ATL oxidizes or isomerizes (up to 20%) to less colored, more oxidizable cis‐forms which either autoxidize or revert to ATL. Processing and storage conditions influence distribution between two routes. Stage II: all forms autoxidize. Oxidized degradation products and fragments accumulate, with product fading and off‐flavor. Presented scheme integrates available information, enables both kinetic and technological system considerations. Knowledge of lycopene behavior aids in improving tomato powder color retention and

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1979.tb10011.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY