摘要:

SUMMARYRelatively mild preslaughter temperature treatments, involving warm air, cold air, and cold air with an ice‐water spray, were administered, singly and in various combinations, to simulate extremes in environmental conditions and fluctuations. Cold‐air treatment improved mean 24‐hr color‐structure scores and expressible‐juice ratios, although a few animals responded adversely to this treatment given singly. Improvement in these parameters was the most significant and consistent in the muscles of pigs subjected to a change from a warm‐air to cold‐air environment. Rate of pH decline was significantly slower (P<.05) in muscles of pigs from groups involving warm‐to‐cold treatments than in control animals. Although glycogen and lactic acid levels at death were altered by treatment, glycogen levels were decreased the most by the warm‐to‐cold treatments. These improvements resulting from a change in environment from warm to cold, were observed even though the treatments were not severe enough to cause a decrease in muscle temperature. Thus, a sudden change from a warm‐air to a cold‐air ante‐mortem temperature, even when of short duration and not severe enough to reduce muscle temperature at death to levels below normal, altered the post‐mortem glycolytic rate and associated properties of porcine musc

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01803.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYSamples of 6 commercial varieties of peaches–5 freestone (Ranger, Triogem, Sun‐high, Elberta, and Afterglow), and 1 clingstone (Ambergem)–were examined at 4 stages of postharvest ripeness. Fresh fruit samples were tested for firmness and analyzed for pectin‐esterase activity and for three pectin fractions (water‐soluble, Versene‐soluble, and Versene‐insoluble). Shear press readings were taken on the corresponding canned samples as well as subjective firmness ratings for each variety at each stage of ripeness.In Ambergem, the proportions of the three pectin fractions remained relatively constant in fruits held 4 days at 25°C. In freestone peaches, the proportion of water‐soluble pectin increased rapidly at the expense of the other two fractions. There were significant statistical differences between the freestone varieties in the proportions of Versene‐soluble pectin retained with advancing ripeness. The differences in pectin constitution were related to the firmness of the fresh and canned products. Pectin‐esterase activity was markedly lower for Elberta than for the other freestone varieties. The level of pectinesterase activity was not in itself related to firmness retention but may be involved indirectly in demethylation

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01804.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYChanges in lipid composition during wheat development were followed by qualitative and quantitative thin‐layer chromatography (TLC) and by fractionation on silicic acid columns. Development of the wheats was accompanied by a slight decrease of lipid content on an as‐is basis, and by almost doubling of lipids on a kernel basis. Free fatty acids in mature wheat were less than half the amount in wheat 21–23 days preceding ripeness. A similar decrease was found in the levels of mono‐ and diglycerides. No consistent changes were found in phospho‐lipid fractions of lipids extracted from wheat at various stages of maturity. Carotenoid pigments disappeared as the wheat kernel developed an

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01805.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYFour sets of eight tomatoes were subjected to four blanching times of 30, 60, 90, and 120 set at 100°C. Two fruits in each set were also subjected to holding times of 5, 10, 15, and 20 min between the blanching and exhausting operations. Pectic substances were determined as water‐soluble, ammonium‐oxalate‐soluble, and dilute‐hydrochloric‐acid‐soluble fractions. The methoxyl content of each fraction was also determined. Firmness was determined by objective measurements. The 30‐see blanching treatment yielded the firmest tomatoes. These fruits were also characterized by the highest content of ammonium‐oxalate‐soluble pectin. The activity of pectin methylesterase was highest in treatments consisting of 30 see of blanching and a lo‐min holding time. The activity of pectin methylesterase seemed to be greatly suppressed after

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01806.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYDark Green Bloomsdale spinach was grown in the fall and in the spring to study the effect of stage of development upon the distribution of total and soluble oxalates in the plant. The total oxalate content of fall‐grown spinach was highest 32 days after planting, with the amount decreasing as the plant developed vegetatively. Spring‐grown spinach was highest in total and soluble oxalates 32 days after planting, with the amounts decreasing as the plants developed vegetatively. Leaves harvested earlier in growth were higher in total oxalates than leaves harvested when older. The concentration of total and soluble oxalates was highest in the leaves, petioles, and roots, in that order. The total oxalates were closely correlated between the leaves, petioles, and roots. Soluble oxalates were closely correlated between leaves and petioles, but not in the roots. The oxalates in all plant parts were predominantly in the soluble form. Analysis of leaf tissues for total oxalates could indicate the level to be expected in the petioles and roots. The level of soluble oxalates in the leaves and petioles could also be predic

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01807.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYTwelve sets of canned tomatoes, each set composed of three fruits harvested from the same plant and subjected to different ripening conditions, were analyzed for pectic constituents. Firmness was highly significantly correlated with total pectic constituents and with the ratio of the carhonyl and pectic content. Correlation between firmness and mineral content was also significant. These results indicate that a high content, large molecular size, and a low methoxyl content of the pectic constituents result in firmer tomatoes. From the results it appears that firmness is related to retention of the original pectic content and controlled demethylation. This induced demethylation increases the extent of ionic bonding and results in firm fruits.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01808.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Crystallization of water in tissue has received considerable study (Heard, 1955a, b; Maurer and Murray, 1951; Meryman, 1957; Parkes, 1957; Smith, 1961; Woodroofet al., 1946). In many instances the conclusions concerning tissue disruption and crystal location (intra‐ or extracellular) are based on observations of specimens from which the ice crystals have been removed. The ice is usually removed by lyophilization, solvent extraction, or a combination of the two (Humason, 1962; Sass, 1961; Heard, 1955 a, b; Rapatz and Luyet, 1959). Specimens prepared in this manner contain numerous voids which, according to Parkes (1957, p. 524) “presumably represent the spaces occupied by ice crystals.” To our knowledge, no one has published information demonstrating how accurately the void spaces represent the size and location of ice crystals. The information which follows should be of some value in that re

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01809.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYA total of 576 samples of apple juice stored at 0, 37, 72, and 91 °F were analyzed during a period of 242 days. Of these, 283 were analyzed for acetylmethylcarbinol (AMC), 195 for diacetyl, and 98 for ethyl alcohol. There was no significant decrease in quantity of AMC or ethyl alcohol in apple juice in tin cans and glass bottles during the storage periods. The level of diacetyl, however, declined at a significant rate when diacetyl had been added to apple juice in bottles and stored at 91 and 72°F for 219 days. Only AMC was tested for its stability during repeated thawing and re‐freezing periods. No significant changes occurred in the quantities of AMC present in these frozen samp

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01810.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYGas chromatographic examination of the volatiles of cured and uncured ham showed that hexanal and valeraldehyde were present in appreciable quantities in the uncured product hut were barely detectable in the volatiles of the cured meat. The differences were less pronounced in the contents of hutyraldehyde, propionaldehyde, and acetaldehyde between cured and uncured ham volatiles, though these aldehydes tended to be more prevalent in the uncured ham. The branched‐chain aldehydes (isobutyraldehyde, isovaleraldehyde, 2‐methyl‐hutyraldehyde) occurred to the same extent in both meats. Acetone was found to represent a major carhonyl constituent of the volatiles in both cured and uncured ham. The sulfur‐containing fractions of the volatiles from both meats were found to comprise hydrogen sulfide and metha

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01811.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYHard‐maple sawdust was sifted on a con‐trolled‐temperature hotplate for smoke production. The acids, total phenols, and carbonyl compounds were determined on the steam‐volatile and non‐steam‐volatile portions of both whole smoke and the vapor phase. Most of the compounds in these groups were found to be steam‐volatile.Several steam‐volatile monocarboxylic acids and monocarbonyl compounds were isolated and identified from smoke. The C1–C10acids were found to be present in whole smoke, with the C1–C10acids occurring in the greatest concentrations. Only C1–C10acids were found in the vapor phase of the smoke. The following monocarbonyls were identified in the steam‐volatile portion of whole smoke: 2‐pentanone, valeraldehyde, 2‐butanone, butanal, acetone, propanal, crotonaldehyde, and ethanal. In addition, tentative identification of isovalderaldehyde and methanal was made on the basis of a comparison of chromatographic behavior and absorption spectra of the

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1965.tb01812.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY