摘要:

ABSTRACTAntioxidants, citric acid and ascorbic acid did not affect the initial slow oxidation of myoglobin but extended the time before rapid oxidation began. NaCl increased the initial rate of pigment oxidation. Lipid extracted from freshly ground, lean beef increased the rate of myoglobin oxidation when added to freshly ground lean beef while lipid extracted from ground beef stored for 7 days did not. Added linoleic acid was more effective than trilinolein in promoting myoglobin oxidation. Lipase and lipoxygenase enhanced the rate of pigment oxidation while phospholipase A inhibited it. Oxalate inhibited both lipid and myoglobin oxidation and reversed the pro‐oxidant capacity of Fe+2. EDTA also inhibited lipid oxidation but promoted myoglogin oxidatio

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb12552.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTHistochemical and histological properties were determined for the longissimus and gluteus medius muscles from beef carcasses which exhibited musculature of the four following quality groups: (1) normal in color, firmness and exudation; (2) normal in color but soft and exudative; (3) pale in color, soft and exudative; and (4) dark color, firm and dry. Differences were observed among quality groups for muscle fiber area and muscle fiber type. A greater proportion of ATPase olRed type fibers was observed in groups 2, 3 and 4 compared to group 1, indicating that muscles from these three aberrant groups differ in metabolic potential.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb12553.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTThe objective of this research was to evaluate three different methods of affecting meat tenderness by treating pre‐rigor muscle. The muscle relaxants (phosphate and magnesium chloride), a glycolytic inhibitor (sodium citrate) and microwave cooking were tested for improvement in post‐rigor tenderness. The results indicate that microwave cooking of pre‐rigor muscle produced a significant tenderization effect when compared to post‐rigor cooking and the magnitude of this difference proved to be greater than 50%. Sodium hexametaphosphate, sodium pyrophos‐phate‐sodium hexametaphosphate and sodium citrate also produced an increase in tenderness when compared with the

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb12554.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTUsing1 5N‐labelled sodium nitrite cured pork bellies, with and without the addition of sodium ascorbate, we have attempted to trace the reaction pathways of nitrite in bacon. The depletion of nitrite, originahy at 156 ppm, was followed during the processing operation. Subsequent experiments during the storage of the1 5N labelled, sliced, vacuum packaged bacon showed the further depletion of nitrite in both the lean and adipose tissue portions, the lower nitrite levels being found in the bacon to which ascorbate had been added. The formation and depletion of nitrate was also noted. Analysis of the protein and lipid portions showed incorporation of1 5N into both. Mass spectral measurements showed that between 73 and 87% of the added1 5N remained in the bacon lean portion. The adipose portion contained much less1 5N, equivalent to between 20–25% of that added. A hot water extract of both lean and adipose fractions showed the presence of1 5N greater than the1 5N due to nitrite and nitrate. One effect of the addition of ascorbate was to force1 5N into water soluble compounds. Examination of connective tissue protein isolated from the adipose tissue portion showed incorporation of1 5N equivalent to 6 ppm NaNO2in bacon without ascorbate compared to 2.5 ppm for bacon with added ascorbate.1 5N data also showed incorporation of approximately 25% of the added nitrite into the muscle proteins of both bacons, and incorporation of 10% of the added nitrite into the lipid fraction of the adipose tis

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb12555.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTAn improved muscle protein solubility method has been developed which has two distinct advantages over the traditional method: it requires much less time and may be conducted at room temperature. The pre‐ or post‐rigor sample is homogenized in a Brinkman Polytron in 25 ml buffer and is centrifuged. The supernatant is decanted and soluble protein determined as in the traditional method (biuret). Comparable results were obtained for old vs new method for samples of porcine longissimus muscle which encompassed a wide range of sarcoplasmic and myofibrillar protein solubilities. The new method can also be applied with accuracy equivalent to the traditional method for the determination of solubility in cooked meat samples. A four‐factor response surface experimental design (central composite) was utilized to evaluate the role of process variables and product ingredients on the cooking losses of USDA Utility grade biceps femoris muscle. The factors were cooking time (0.5–12.0 hr), temperature (55–85°C), NaCl (0–4%), and Na tripolyphosphate (0–0.5%):Shrink was determined on ground 25‐g samples by calculating the free moisture lost (as a percentage of total moisture) after centrifugation in Wierbicki tubes. Sarcoplasmic and myofibrillar protein solubility were determined on the same samples by the rapid solubility technique. Stepwise regression was used to tit a multiple polynomial equation to shrink loss and protein solubility (P<0.001). The results indicated that cooking temperature was decisively the most important factor controlling yield and protein solubility. Shrink and protein solubility were nearly independent of time in the center point regions of the experiment which are, based on the type of design (central composite), the most accurate areas for prediction. Previous studies have demonstrated that the major tenderization reactions in beef are dependent both on time and temperature. Therefore, these findings suggest that improved yield in commercial thermal processes is possible by selecting long‐time, low‐temperature treatments since protein solubility and, therefore, yield are primarily functions of temperature and are relatively independent of time at

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb12556.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTCrabmeat is processed commercially at 85°C and held at refrigeration temperatures in order to extend shelf life. It was the purpose of this investigation to examine both the anaerobic and aerobic microflora in crabmeat prior to pasteurization and after pasteurization and storage. Anaerobic bacteria from crabmeat were isolated, quantitated and identified using the VPI&SU anaerobic culture system. Unpasteurized crabmeat contained about lo6to 107anaerobes plus facultative aerobes /g and pasteurized crabmeat contained about 105anaerobes plus facultative aerobes/g. After storage for 3 months at 3.3°C, counts increased to about 108to 109/g. The majority of the isolates in both unpasteurized and pasteurized crabmeat were lactic acid producing, nonsporeforming, Gram positive rods. The lactic acid producing isolates from unpasteurized crabmeat produced hydrogen sulfide and grew at 37°C; however, after pasteurization, the isolates neither produced H2S nor grew at 37°C. Heat resistance of the isolates was determined both in pH 7.20 phosphate. buffer and crabmeat homogenates (pH 7.26). Decimal reduction times in phosphate buffer at 55°C were about 2.5 mm for most isolates. No evidence was obtained that the isolates would survive pasteuriza

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb12557.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTHydrogen sulfide production during heating of raw, precooked, and canned tuna was studied by reflux‐trap technique. Raw tuna homog‐enate did not produce hydrogen sulfide gas when heated at less than 90°C. Canned and precooked samples produce substantially higher amounts of H2S during heating than the raw substrate. Maximum H2S production rate occurred after 150 min for raw, 90 min for precooked, and 60 min for canned samples. An apparatus was devised for quantitative determination of H2S gas present in a sealed can of tuna. Cans of control albacore tuna (Thunnus alalunga) packed in water or oil and retorted for 80 min contained higher amount of H2S than the spoiled cans. Hydrogen sulfide content, volatile acids, volatile reducing substances, and histamine values of both the control and the spoiled canned tuna increased significantly as the retort lime was extended from 80 to 120. to 240 min. Headspace profile of canned tuna volatiles was determined by gas chromatography. Examination of the chromatograms indicated a considerable increase in concentration of volatiles as the retort time was extended from 80 to 120 to 240 min in both control and spoiled substr

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb12558.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTThe dark flesh of mullet (Mugil cephalus) was compared with beef muscle for total iron, total hemoprotein, and total nonheme iron. Mullet dark flesh contained 57.3 ppm iron, over twice the amount in beef, 26.0 ppm. Total possible nonheme iron content of mullet dark flesh ranged from 56–75%, compared to 11–29% for beef. In a linoleate emulsion model system, mullet dark flesh homogenate was analyzed for heme and nonheme iron activity as lipid oxidation catalysts. Addition of ascorbic acid, EDTA, and cyanide, at different pH levels, indicated the nature of the catalyses. Of the additives, cyanide yielded the strongest inhibition on a molar basis. Based on the criteria of other researchers, these data suggest that heme iron is the major catalyst of lipid oxidation in mullet flesh. The rates of O2uptake by mullet dark flesh homogenate and by Fe/EDTA increased with increasing acidity, rather than exhibiting a previously reported peak at pH 5.5. The latter appears to be a phenomenon of limited occurrence rather than a general test criteria. In light of this finding, the nature and nomenclature of biological nonheme iron is discus

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb12559.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTThe anthocyanin pigments responsible for the violet color of the tropical tuberDioscorea tryphidawas investigated. The pigments were extracted with 0.1% HCI in methanol, purified with Dowex 50W × 4 cation exchange resin in the hydrogen form and further purified by paper chromatography. The identification of the pigments was based on Rfvalues in different solvents, partial acid hydrolysis, sugar moiety, alkaline degradation, fluorescence under ultraviolet radiation, color reactions and absorption spectra in the visisble and ultraviolet regions. The pigments were identified as follow: peonidin 3,5‐diglucoside, malvidin 3,5‐diglucoside and malvidin 3,5‐diglucoside‐feru

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb12560.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTMaleic hydrazide (MH), a sprout inhibitor, was applied to potato plants in each of 2 yr. Tubers from these plants were examined for susceptibility to enzymatic discoloration and lipid content. Enzymatic darkening was greater, and both the crude lipid and phospholipid content lower, in tubers from plants treated with MH as compared with the controls. The fatty acid composition of the phospholipid fraction of MH‐treated tubers exhibited a significant increase in saturated fatty acids and a decrease in unsaturated fatty acids. The exact mechanism of action of MH is unknown, but its effect on the lipid composition of tubers may be an important factor contributing to sprout inhibition. Since the lipid of the tuber is an important determinant of cellular integrity, the altered lipid composition resulting from treatment with MH may be an important factor contributing to the tuber's increased susceptibility to bruising and discoloratio

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1977.tb12561.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY