摘要:

ABSTRACTResearch was undertaken to establish relationships between volatile levels in the juice of fresh apples, determined by GLC headspace vapor analysis, and other objective indices of maturity and ripeness. Mclntosh apples were tested individually after harvest or following storage and ripening. Volatile levels in the juice were correlated with titratable acidity, Magness‐Taylor firmness and stiffness coefficient values. The stiffness coefficient is derived from nondestructive sonic resonance frequency measurements and has potential value for sortin

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb01214.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTSampling involved maceration of apple tissue in acidified 2,4‐dinitrophenylhydrazine, followed by extraction of the carboxyl‐2,4‐DNP‐hydrazones with benzene. Acetaldehyde‐2,4‐DNP‐hydrazone was separated and purified by TLC and quantitatively determined by UV spectroscopy at 354 nm. The identity of acetaldehyde‐2,4‐DNP‐hydrazone was confirmed by mass spectroscopy and gas‐

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb01215.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTA simple gas chromatographic technique was developed for the quantitative determination of organic acids and reducing sugars in fermenting cucumber juice. Acids and sugars were simultaneously chromatographed as their trimethylsilyl derivatives with no prior fractionation reqdired. A 3% OV‐17 column provided resolution of acids, sugars and trimethylsilylimidazole, the silylating agent and solvent. Accurate quantitation of fructose and glucose consumption and lactic acid production were qbtained for cucumber juice samples fermented byLactobacihs plantarumculture. The average and range of the average deviations of duplicates for all samples tested were ±0.015% and 0.001–0.045%, respectively. A study on the recovery of added acetic acid, lactic acid, glucose, and fructose was conducted with an average % redovery of 98.4% and a range of 95.2–

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb01216.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTThe level of methyl anthraniiate was determined in several wines of native American varieties and of related hybrids. In order to evaluate its contribution to the “foxy” aroma that is often associated with these wines, sensory analyses were conducted to estimate the threshold of methyl anthraniiate in wines and to compare its concentration with the perception of “foxiness.” The gas chromatographic analysis reveals that the level of methyl anthranilate varies widely among grape varieties. Not ail wines termed “foxy” exhibit high levels of this compound. Methyl anthraniiate may be an important aroma constituent in a few native varieties but the characteristic “foxy” flavor is not solely due

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb01217.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTThe interacting effects of ascorbic acid and metal ions on carotene oxidation were studied in an aqueous carotene‐linoleate solution at pH 7. Ascorbic acid at concentrations up to 10—3M was a prooxidant. Fe3+and, to a lesser extent Co2+, acted synergistically with ascorbic acid, the prooxidant effect increasing with metal concentration. Cu2+formed a prooxidant system with ascorbic acid only at low metal concentration, but as the copper concentration was raised, inversion of activity occurred and the copper‐ascorbic acid system exerted a stabilizing action on carotene. Prooxidant effects were enhanced and antioxidant effects weakened in the presence of added lmoleate hydroperoxides. The latter were unstable in the presence of ascorbic acid and especially ascorbic acid + Cu2+. Ascorbic acid itself became unstable in the presence of Cu2+. Oxygen depletion, brought about by the rapid oxidation of ascorbic acid, may be partly responsible for the carotene‐stabilizing effect of the Cu*+‐ascorbic acid couple. It is postulated that additional stabilization results from the radical‐scavenging properties of copper or of a copper chelate formed by ascorbic and/or dehydro‐

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb01218.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTThe objective of this work was to prepare a soy‐fortified corn dough having the same rheological properties as the unfortified material. Water sorption isotherms and hydration kinetics of pregelled corn‐flour, corn‐soy and starch powder systems were investigated. The effect of adding processed full‐fat soy flour on hydration, reconstitution and rheological properties of dough systems were studied with Brabender Farinograph and Extensograph instruments. Soy flour imparted an undesirable plasticizing effect on pregelled corn doughs. Rheological properties of model dough systems were studied to solve this problem. Results indicated this effect could be reversed by the addition of pregelled tapioca starch as an elasticizing agent. A corn flour:soy flour:tapioca starch::60:30:10 mixture produced a dough with rheological properties similar to those of a corn flou

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb01219.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTScanning electron microscopy (SEM) was used to determine the influence of sodium stearoyl‐2‐lactylate (SSL) and/or 6% Single Cell Protein (SCP) supplement on dough structure. Dough samples were mixed to optimum development according to farinograph peak times and absorptions before examination by SEM. Supplementation with SCP thickened gluten sheets; contours of starch granules were masked and rupture of gluten increased. Addition of SSL to dough improved gluten sheeting and adding SSL to the SCP dough at least partially counteracted the adverse effects of SCP on the gluten la

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb01220.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTExtraction of defatted rapeseed meal at alkaline pH followed by neutralization of the extract gives a protein isolate in a low yield. This material was found to be rich in acidic proteins and to contain all of the high molecular weight proteins. Quantitative recovery of the extracted proteins was achieved by adding ananionic polymer to the extract prior to acidification. Both methods were found to give protein isolates with a chemical score of 100. The isolates contained proteins with a variety of isoelectric points. A soluble complex between rapeseed proteins and CMC was shown to exist at pH 11.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb01221.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTIn short‐term studies, substitution of dietary sucrose (50%) with wheat flour or its starch component caused, in hypercholesteremic young male rats, an appreciable decrease in fasting serum cholesterol levels; patent flour showed a more pronounced such effect than high‐extraction flour. Liver cholesterol levels were also greatly reduced in flour‐fed rats. Substitution of dietary sucrose with wheat gluten substantially reduced the liver accumulation of cholesterol, triglycerides and phospholipids but lowering effect on serum lipids was mostly observed under the condition of partial, rather than complete, substitution of sucrose with g

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb01222.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTLeaf protein concentrate (LPC) haa been shown to have the phenolic acid, chlorogenic acid, bound to its protein molecules. Bound chlorogenie acid creates off color problems in foods containing LPC as an ingredient and also possibly lowers the digestibility of LPC by inhibiting the rate of trypsin attack on the protein. A buffer, containing 2.5% NaCl‐1 mM mercaptoethanol‐40 mM phosphate, effectively removed 69% of the chiorogenic acid from LPC. LPC, with the majority of its chlorogenic acid removed, had an enhanced in vitro protein digestibility and an amino acid pattern very similar to that of the original LPC. A series of small molecular weight proteins were found to be the chlorogenie acid binding fraction in

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb01223.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY