摘要:

SUMMARY—A comparison of different ways of treating reflectance data showed that K/S ratios were best suited for quantitative analysis of myoglobin derivatives in intact meat samples. Evidence was found for a change in the average path length of light reflected from a water suspension of a myoglobin‐dried milk mixture. The average path length decreased in the region of an absorbancy peak. The ratios of K/S values derived from reflectance data on myoglobin derivatives can be quite different from the ratios of absorbancy coefficients of the same derivatives at the same wavelengths but obtained by transmission spectrophotometry. Results with a myoglobin‐dried milk suspension showed that the nature of the blank used for reflectance had an important influence on the K/S

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1967.tb01304.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARY—The nonenzymic production of gas in food products stored under tropical conditions can, in many cases, be attributed to the reaction between free amino acids and reducing sugars. Carbon dioxide production in model systems has been studied and its relationship to brown pigment and conjugated unsaturated carbonyl compounds investigated.Over a wide range of pH the variations of sugar, amino acid and temperatures used showed that the type of sugar was the limiting factor in rate of carbon dioxide production rather than the amino acid. Rate increased from disaccharide to hexose to pentose and with rise in pH and temperature. However relative reactivity is a temperature dependent function for lactose and glucose because of the different activation energy involved.Carbon dioxide was formed mainly via the Strecker degradation but it has been demonstrated that another unidentified pathway is available for the formation of carbon dioxide from sugars in the presence of amino compounds.Evidence for the similarities in reaction pathways for the formation of the three end products—carbon dioxide, brown pigment and conjugated unsaturated carbonyl compounds‐is presented. The possibility of using the determination of carbonyl compounds as a sensitive indicator of future spoilage due to gas formation is sugg

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1967.tb01305.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARY—Cling peaches(Prunus persicavar. ‘Halford’) were canned with 36° Brix syrup in no. 2% cans as peeled halves. The polyphenolic compounds were extracted from the drained peaches with 95% ethanol containing 0.1% HCl. The extract was concentrated in a flash evaporator under vacuum to remove the ethanol, and with petroleum ether to remove carotenoids. The polyphenolic compounds were extracted from the concentrate with ethyl acetate and separated by two‐dimensional paper chromatography, with n‐butanol‐acetic acid‐water (4:1:5 v/v) and 2% acetic acid as solvents.Shown to be present in the extract were four chlorogenic acid isomers, five leucoanthocyanidin isomers, catechin, epicatechin, isoflavone, two p‐coumarylquinic acids, and caffeic acid. Chlorogenic acids, leucoanthocyanidins, and catechin were present in larger amount

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1967.tb01306.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARY—Studies were conducted on the lipid composition of 10 normal and 10 pale, soft exudative (PSE) longissimus dorsi muscles of porcine animals. No significant differences, between normal and PSE muscles, were noted in total lipid or fatty acid composition. Likewise, neither lipid content or composition appeared to be related to the post‐mortem extract‐ability of myofibrillar and sarcoplasmic pro

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1967.tb01307.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARY—The stimulation in the presence of methylene blue of the enzymic production of nitric oxide from added nitrite by pork muscle minces under anaerobic conditions and the partial suppression by nitrite of the aerobic respiration of the minces suggested that the respiratory system is involved in nitrite reduction. Using mitochondrial preparations from pork skeletal muscle, it was shown that under anaerobic conditions the mitochondria can utilize nitrite with formation of nitric oxide. Ferrocytochrome c has been located as the immediate substrate involved, the mediating enzyme being cytochrome oxidase, suggesting that under anaerobic conditions nitrite can replace oxygen as the terminal point of the respiratory chain.In the absence of a reducing agent nitrite oxidizes myoglobinin vitroto the met‐form. The reduction of metmyoglobin by pork muscle minces was erratic and reduction by mitochondria has not been observed. Mitochondria can, however, readily reduce nitric oxide metmyoglobin and this observation suggests a possible mechanism for the formation of nitric oxide myoglobin during curing.Observations on mature curing brines from Wiltshire bacon factories indicated that, although active in utilization of nitrite and nitrate, they do not produce nitric oxide. The tissue enzymes, therefore, appear to be the sole agents for producing nitric oxide and thus cured meat co

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1967.tb01308.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARY—Changes in length and ‘extension’ during the onset of rigor mortis in cyclically loaded strips of ox sternomandibularis muscle were found to be markedly different at 1 °C from those at temperatures over the range 537°C. The delay phase of rigor mortis was longer with lower temperature within the range 1.537°C, but was shorter with lower temperature within the range 1.15°C. The onset phase was longer with lower temperature within the range 5–37°, but was shorter at 1° than at 5°C.The change in extension was completed sooner at l° than at 5° or 15°C. At 37°C, by the time the change in extension was complete, acid‐labile phosphorus had fallen to a low level, and the ultimate pH was closely approached or reached; but at 1°C, an appreciable amount of acid‐labile phosphorus still remained, and the pH was considerably above the ultimate value. The shortening at 1 °C was comp

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1967.tb01309.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARY—Samples of onions and bell peppers were taken during various stages of high‐ and low‐temperature dehydration and lyophilization to ascertain the step‐wise changes that occur in the crystallinity of cellulose. Cellulose crystallizes mainly during the later stages of drying in all three processes, and freezing produces only a minor amount of crystallization. Most of the water loss and loss of rehydration capacity occurs at the start of dehydration. The latter is ascribed to cell death and loss of differential permeability in protoplasmic membranes. Rehydration volume is related to crystallinity of cellulose in these materials within each method of dehy

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1967.tb01310.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARY—Twenty‐one pigments were isolated from the hydrocarbon fraction of watermelon carotenoids. Fourteen of these are naturally occurring carotenes, the remaining seven are stereoisomers and probably artifacts. Lycopene and its neo‐isomers were the major pigments (73.7% and 7.6%, respectively, of the total pigment). Other pigments present in appreciable quantities were phytoene (2.1%), phytofluene (1.4%), beta‐carotene (4.1%), zeta‐carotene (1.6%) and gamma‐carotene (0.4%). Alpha‐carotene, poly‐cis‐lycopenes and an unknown pigment were also present in

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1967.tb01311.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARY—The organic volatiles in commercial Delicious apple essence were extracted and reduced to an oil by five different extractants: isopentane, diethyl ether, charcoal (with elution by ether), liquid carbon dioxide, and 1,2‐dichloro‐1,1,2,2‐tetrafluoroethane. Identification and quantitative estimation of the maior constituents were made by gas‐liquid chromatography and mass spectrometry. Isopentane and the fluorocarbon were similar in action. Compared with ether they gave lower recoveries, especially for the low‐molecular‐weight alcohols, but they gave extracts with higher concentrations of esters and aldehydes and thus are useful for further composition studies. Liquid carbon dioxide gave an extract similar to that given by ether.Adsorption on charcoal gave generally good recoveries and was outstanding for alcohols. Panel tests indicated that the low‐molecular‐weight alcohols have only minor importance, if any, to apple aroma. A major proportion of the principal aroma‐bearing constituents was extracted

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1967.tb01312.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARY—To determine the influence of fascicular organization and disposition of muscle stroma on the deposition of interfascicular' lipids, six muscles representing two contrasting structural types were selected from each of five littermate pigs exsanguinated at different stages of growth. Looseness of fascicular organization, as determined subjectively by microscopic examination, generally paralleled the quantity of interfascicular lipid as determined by chemical analysis.In addition, the tendency for percentage of this lipid to increase with growth and maturity was generally more evident in the loosely organized muscles of the trunk and proximal segments of the forelimb than in the tightly bound, consolidated, fusiform muscles nearer the extremitie

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1967.tb01313.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY