摘要:

SUMMARY:The effect of psychrotolerant bacteria on the water‐holding capacity as measured by the extract release volume (ERV), pH and protein degradation in chicken skin stored at 5°C was determined using strains of Achromobacter and pigmented and nonpigmented Pseudomonas. All organisms caused a rapid decrease in ERV to about 50% of the original value during the early log phase of growth before development of off‐odor. Changes in pH and content of extractable nitrogenous materials occurred during bacterial growth but were not pronounced until after the count was greater than 108cells/g of skin and a faint off‐odor was detectable. The content of extractable materials decreased during the early log phase, corresponding to the period of rapid increase in pH; later, during the late log or stationary phases of growth, it rapidly or gradually increased, depending on the or

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1970.tb12113.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARY:Components of the molecular structure of epimysial acid‐soluble collagen (ASC) from meats of varying tenderness were studied by several methods. The ASC was studied since it contains an appreciable amount of intramolecular cross‐links but is still soluble. Though the amount of total collagen in epimysial tissue was found to have no correlation with meat tenderness, the molecular studies indicated some correlation of the type of epimysial ASC with meat tenderness. Sucrose density‐gradient ultracentrifugation analyses of denatured epimysial ASC suggested that this type of collagen contains a lesser degree of cross‐links when obtained from tender meat samples. Viscosity measurements were found to be correlated to tenderness of meat in a manner similar to the results obtained by ultracentrifugation, in that the intrinsic viscosity of epimysial ASC from tender meat was lower than that from tough meat, indicating differences among the relative sizes of the collagen molecules from the different samples. Partial amino acid analyses of the epimysial ASC samples via gas chromatography showed no differences in the levels of aspartic, serine or hydroxyproline, amino acids which may be involved in the ester type of cross‐links. Results of chemical estimation of the ester type of cross‐links indicated that the proportions of esters in the various ASC samples were similar. The amount of lysine was found to be significantly higher (P<0.05) in epimysial ASC from tough meat compared to tender meat, suggesting an increased potential of the aldehydic‐type of cross‐link, which is formed via an aldol condensation of two aldehydes derived biosynthetically from lysine. This was strengthened by the results obtained in the chemical estimation of the aldehydic‐type of cross‐link, in that the epimysial ASC of tough meat contained significantly more aldehyde than did that of t

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1970.tb12114.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1970.tb12115.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARY:DTA (differential thermal analysis) thermograms of epimysial connective tissue from normal and low quality porcine muscle were compared at 0 and 24 hr post‐mortem. In addition, the melting characteristics of intramuscular collagen were determined at 0 hr post‐mortem. In all tissues studied, collagen from low quality muscle consistently gave slightly lower peak melting points than that from normal muscle. Epimysial collagen had a significantly (P<.05) lower peak melting point at 24 hr than at 0 hr post‐mortem (64.24 vs. 65.77°C). Using epimysial collagen, a significantly (P<.01) greater proportion of the total melting range occurred at lower temperatures at 24 hr post‐mortem as compared to 0 hr (4 1.1 vs. 30.9%). The thermal behavior of intramuscular collagen at 0 hr post‐mortem was similar to that of epimysial collagen at 0 hr, but peak melting temperatures were slightly higher for intramuscular connect

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1970.tb12116.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARY:Extracts of orange juice vesicles oxidized p‐hydroquinone (HQ) and o‐dihydroxyphenylalanine (DOPA) with O2. Most of the oxidase activity was associated with a particulate fraction that sedimented at 100,000 × g. Sonic disruption of the particulates followed by chromatography on DEAE‐cellulose increased specific activities with both substrates. The partially purified enzyme oxidized numerous naturally occurring o‐diphenols and o‐methoxyphenols. Acidic media below pH 4 and heating above 70°C destroyed most of the oxidase activity. KCN, diethyl‐dithiocarbamate and 8‐hydroxyquinoline but not EDTA inhibited the oxidase. The partially purified enzyme reduced benzoquinone and oxidized the reduced form of nicotinamide‐dinucleotide (NADH). Ubiquinone, a benzoquinone derivative, but not menadione or vitamin K1, naphthoquinone derivatives, could replace benzoquinone in the oxidation of NADH. Ubiquinone, benzoquinone and similar p‐quinones may function in the orange as the oxidation‐reduction couple between NADH‐quinone reducta

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1970.tb12117.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARY:The functional capillary system was investigated by injecting trypan blue dye into 8 market‐weight porcine animals followed by extracting the dye from various muscles. The trapezius contained more dye than the biceps femoris, with the gluteus medius and longissimus dorsi being equal in dye content but containing less dye than the trapezius and biceps femoris muscles. This rank compared well with the fiber type distribution, with the trapezius being high in red fiber content. The method presents possibilities for study of capillary function but some problems were encountered with the injection procedur

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1970.tb12118.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARY:The viscosities of selected fruit juices and purees were measured with a coaxial‐cylinder viscometer in the temperature range 20–70°C. Depectinized apple juice and Concord grape juice were Newtonian fluids at all concentrations and their viscosity decreased considerably at higher temperatures. Cloudy apple and orange juices changed from Newtonian to pseudoplastic at concentrations higher than 50 and 20° Brix. respectively. Temperature had a smaller effect on viscosity of cloudy juices than of clear juices. The apparent viscosity of fruit purees (pseudoplastic fluids) decreased slightly at higher temperatures. The activation energy for flow increased with the juice concentration and decreased with the presence of suspended particles in the fruit product. The data and conclusions are useful in the design and operation of efficient food‐processing eq

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1970.tb12119.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARY:The growth support potential of frankfurters for Clostridium perfringens was determined. Inoculated emulsions were stuffed into glass tubes and processed so that they reached an internal temperature of 68–69°C in 30–48 min. The tubes were sealed with agar plugs and rubber stoppers to simulate vacuum‐packaging conditions. Total aerobic and anaerobic bacterial counts in uninoculated raw emulsion were 1 to 3 log cycles higher when petri dishes were incubated at 23°C as opposed to 37°C. The low‐temperature‐growing mesophiles and psychrotrophs were destroyed during processing. The 37°C counts were reduced 1 log cycle and the 23°C counts, 2 to 3 log cycles. Clostridium perfringens reproduced rapidly in frankfurters at 37 and 23°C, more slowly at 15 and 12°C, and not at all during 2 wk of storage at 10° or 4 wk at 0–5°C. Clostridium perfringens made up 2.5–10% of the total anaerobic count at 0 time but became the dominant organism during the storage at all temperat

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1970.tb12120.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARY:A Penicillium roqueforti strain produced maximal amounts of lipase when grown in 0.5% casitone‐1% Proflo broth, pH 5.5, at 27°C. Addition of butteroil, com oil or olive oil to the growth medium inhibited the lipase production. Under pH stasis the partially purified lipase ofP. roquefortihad an optimum pH of 8.0 and an optimum temperature of 37°C. Maximum lipolytic activity occurred with 5% butteroil emulsion as the substrate. Manganese chloride and magnesium chloride stimulated the enzyme activity. Calcium, sodium and potassium sale had no appreciable effect on lipolysis; silver, mercury and zinc salts were inhibitory. The lipase was thermolabile, being inactivated completely within 10 min at 50°C. The lipase hydrolyzed tributyrin, tricaprylin, tricaprin, tripropionin and triolein in decreasing o

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1970.tb12121.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARY:A small fraction, containing evidence for the presence of pyroglutamyl dipeptides and an N‐pyroglutamylhexosamine. was isolated from the edible, commercial mushroom. Agaricus campestris. Upon hydrolysis, this isolate liberated a copious amount of glutamic acid, together with smaller quantities of other amino acids and a hexosamine. Analyses of the unhydrolyzed and hydrolyzed portions of the fraction by an automatic amino acid analyzer revealed the identities and quantities of the compounds released. Additional chemical and physical methods of analysis gave supporting evidence for the presence in the mushroom in addition to proline and pyroglutamic acid of the pyroglutamyl dipeptides of threonine, aspartic acid, valine, leucine, citrulline, phenylalanine, glycine, alanine, glutamic acid and proline and also of the amino acid sugar, N‐pyroglutamylglucosamine. Pyroglutamylcitrulline and N‐pyroglutamylglucosamine were tentatively identified. The first 6 dipeptides are reported for the first time. A mechanism is proposed for the enzymic biosynthesis of the pyroglutamyl dipeptides in the mushroom. Results of the present work shed additional light on the complex nature of the higher basidiomy

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1970.tb12122.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY