Showing papers in "Journal of Food Biochemistry in 1987"

Anthocyanins as food colorants —a review

Abstract: A number of factors affecting anthocyanin stability and color are discussed in this review. The anthocyanins are probably the most spectacular of plant pigments since they are responsible for most of the red, purple and blue pigmentation of flowers, fruits and vegetables. However, because of their highly reactive nature, anthocyanins readily degrade, or react with other constituents in the media, to form colorless or brown colored compounds. The presence of an ox-onium ion adjacent to carbon 2 makes the anthocyanins particularly susceptible to nucleophilic attack by such compounds as sulfur dioxide, ascorbic acid, hydrogen peroxide and even water. Loss of anthocyanin pigmentation also occurs in the presence of oxygen and various enzymes, and as a result of high temperature processing. A certain degree of pigment stabilization may be conferred by acylation with various organic acids, copigmentation, self-association and/or metal chelation. In addition, pH has a marked effect on anthocyanin stability, and on the color of media containing these pigments. A number of anthocyanin-rich sources have been investigated for their potential as commercial pigment extracts. Although their application is primarily limited to acidic media, continued research on the chemistry of anthocyanins may lead to application and stabilization of these pigments in a wider variety of food products.

Lipid oxidation in retail beef, pork and chicken muscles as affected by concentrations of heme pigments and nonheme iron and microsomal enzymic lipid peroxidation activity

Abstract: Muscles of beef, pork and chicken purchased in two seasons were analyzed for lipid oxidation potential, concentrations of total pigments, myoglobin and nonheme iron, and microsomal enzymic lipid peroxidation activity. To determine lipid oxidation potential, thiobarbituric acid (TBA) assays with antioxidant protection were conducted on raw and cooked comminuted muscles stored at 4°C. TBA values of raw chicken muscles (white and dark) and pork muscles were low and changed little during 2–6 days of storage, whereas the values of raw beef muscles were higher and increased progressively. However, TBA values of cooked muscles of all three species increased during 2–4 days of storage with no marked differences among the species. Total pigment and mycglobin concentrations best explained the differences in TBA values of stored, raw muscles among the three species.

A review: enzymatic cross-linking of proteins applicable to foods.

Abstract: The functional properties of food proteins may be changed by the use of specific enzymes. Enzymatic reactions can be carried out under relatively mild conditions and, because of the specificity of the reactions, are not likely to lead to toxic products. Among the several reactions catalyzed by enzymes, some lead to the intra- and intermolecular cross-linking of proteins. In this review, we briefly describe the reactions catalyzed by transglutaminase, lipoxygenase, lysyl oxidase, protein disulfide reductase, protein disulfide isomerase and sulfhydryl oxidase and the feasibility of using these enzymes for cross-linking of food proteins. Very little data are available on the efficiency of cross-linking and the effect on functional and nutritional properties of the proteins.

A review: separation and chemical properties of anthocyanins used for their qualitative and quantitative analysis

Abstract: Methods of analysis for naturally occurring anthocyanins are described. The large number of chemical groups which may bind to the flavylium molecule has contributed to a large variation in structure, making the qualitative analysis of anthocyanins difficult. Qualitative analysis has generally involved preliminary solvent extraction followed by chromatographic separation and purification of pigments. Individual anthocyanins are then characterized by their chromatographic mobility, absorption spectra, and by means of controlled hydrolysis and oxidation tests. Quantitative analysis of anthocyanins may be carried out using either differential or subtractive spectral methods. The validity of results obtained by either of these methods is dependent on the presence or absence of interfering substances within the samples. Where the quantification of individual anthocyanins is desired, their separation from a mixture, normally by means of column chromatography, is first necessary. High resolution of microgram quantities of anthocyanin without the need for extensive sample purification prior to analysis has led to an increase in the use of HPLC techniques for quantitative work.

Lignification: evidence for a role in hard-to-cook beans

Abstract: An investigation was undertaken to establish whether lignification was a possible mechanism contributing to the hard-to-cook defect in beans (Phaseolus vulgaris). Cell wall material (CWM) from control and defective beans was isolated and microscopic techniques employed to compare the two fractions. Transmission electron microscopy indicated that potassium permanganate-fixed material had heavier deposition of manganese dioxide in cell corners, secondary walls and middle lamella of hard beans, a pattern seen during the lignification of plant tissue. CWM from hard beans had a lamellated appearance not seen in the control as viewed by scanning electron microscopy. It is suggested that this is a result of cellulose deposition, a process known to occur before lignification. This tentative evidence of lignin within the cell walls of legume seeds has a host of implications for hydration during cooking, cell separation and ultimately, texture.

Effect of in situ formaldehyde production on solubility and cross‐linking of proteins of minced red hake muscle during frozen storage

Abstract: Three forms of minced red hake muscle representing whole-mince, mince with the low molecular weight fraction removed (reconstituted-minced) and mince with low and high molecular weight soluble fractions removed (washed-minced) were stored frozen with added Fe+2 and ascorbate (trimethylamine oxide (TMAO) was added when necessary). The production of DMA and free formaldehyde was measured as were the decreases in water-soluble and salt-soluble proteins and TMAO as a function of increasing concentrations of ascorbate. Dimethylamine (DMA) production and loss of overall protein extractability were greatest in minced muscle, followed by reconstituted-minced muscle, and least in washed-minced muscle. The minced muscle lost water-soluble proteins, however, less rapidly than the reconstituted-minced muscle. The percentage of formaldehyde that was bound was highest in the minced, next in the reconstituted-minced and least in the washed-minced muscle. This supports earlier data and indicates that formaldehyde reacts with both the small molecular weight fraction and the water-soluble proteins as well as the contractile proteins. Loss of protein extractability in all samples appeared to be heavily dependent on hydrophobic interactions. Disulfide interactions appeared to occur to some extent in the reconstituted-minced and washed-minced muscle but were a minor factor with the minced muscle samples. Surface hydrophobicity of the proteins was inversely related to their extractability. In the sample of minced muscle with the highest concentration of added ascorbate where approximately 79% of the proteins became inextractable, some 2% of the muscle proteins were covalently linked in polymers with molecular weights greater than that of the myosin heavy chains. The data indicate that cross-linking of protein components occurs as well as hydrolysis of a considerable amount of the protein.

Effects of cryoprotectants in minimizing physicochemical changes of bovine natural actomyosin during frozen storage

Abstract: Physicochemical changes in bovine natural actomyosin extracted from prerigor semimembranosus muscle were investigated during frozen storage at −28°C as affected by the addition of cryoprotectants (5.6% Polydextrose® or 5.6% mixture (1:1) of sucrose and sorbitol). Proteins were destabilized during freezing and frozen storage as reflected by decreases in protein solubility, the visual appearance of aggregates in protein sols, decrease in intensity of flow birefringence, intrinsic viscosity and ATPase activity, and changes in size, shape, or charge of the protein (especially myosin) as evidenced by nondenaturing electrophoresis. These effects were reduced to some extent by the two cryoprotectant treatments.

The composition and vitamin a value of the carotenoids of pumpkins of different colors

Abstract: The carotenoid pigments of the yellow and orange flesh varieties of the pumpkins Cucurbita moschata and C.maxima were identified and quantified, α-Carotene, β-carotene, ζ-carotene, β-carotene 5,6-epoxide, β-cryptoxanthin, lutein, taraxanthin, zeaxanthin, luteoxanthin and auroxanthin were detected in the pumpkins. The difference was that the yellow variety of C. moschata had no zeaxanthin. The quantitative patterns of the two varieties were similar. Although some quantitative variation was observed, lutein, β-carotene and luteoxanthin predominated. The difference in the color between the two varieties resulted from these quantitative differences in carotenoid composition. The vitamin A activity of the C. moschata variety with yellow flesh was higher than that of the C. maxima, which had many oxygenated carotenoids.

Collagen in the tissues of squid illex argentinus and loligo patagonica ‐ contents and solubility

Abstract: Collagen was isolated from the skin, connective tissue sheets, and mantle muscle of squid Illex argentinus and Loligo patagonica, by extracting all soluble noncollagenous material. The tissues and the collagen isolates were characterized by determining the total nitrogen, hydroxyproline, and solubility. The contents of hydroxyproline in the collagen isolate of skin, membranes, and muscle of Illex were 5.3, 8.0, and 4.4% dry matter and of Loligo 6.1, 7.4, and 4.9%, respectively. The collagen contents in these tissues were in Illex 4.9, 7.8, and 1.0; in Loligo 3.4, 4.9, and 0.3%, respectively, in the wet material. Collagen preparations obtained from the skin, membranes, and mantle muscle of Loligo yielded, respectively, 9%, 4%, and 8% collagen soluble in citrate buffer. For Illex squid the solubilities were 41%, 6%, and 21%, respectively.

TEMPERATURE ACCLIMATION OF ATLANTIC COD (GADUS MORHUA) AND ITS INFLUENCE ON FREEZING POINT AND BIOCHEMICAL DAMAGE OF POSTMORTEM MUSCLE DURING STORAGE AT 0° and ‐3°C

Abstract: The freezing point of muscle fluid from Newfoundland Atlantic cod held at ambient sea water temperature was as low as - 1.30°C in March and as high as - 0.80°C in July. Muscle fluid from cod held live at 0°C for 3 weeks had a freezing point of - 1.02°C in contrast to a muscle fluid freezing point of - 0.90°C for cod acclimated at 10°C prior to sacrifice. Muscle fluid from cold acclimated cod exhibited 0.40°C thermal hysteresis indicating freezing point depression was influenced by antifreeze substances. The following indices of deterioration were measured in muscle sections stored at 0°C or - 3°C for 21 days: extractable protein (EP), free drip (FD), extracellular area (EA), trimethylamineoxide (TMAO), trimethylamine (TMA), dimethylamine (DMA), free amino acids (AA), and pH. Muscle sections at the anterior end of fillets, from myotomes 9–20, prepared using aseptic technique and treated with antibiotic showed less evidence of biochemical deterioration: (a) when stored at - 3°C compared to 0°C with respect to EP, AA, EA; (b) when prepared from fish acclimated at 0°C compared to at 10°C and stored at 0°C or - 3°C with respect to EP, EA, FD, AA. Negligible changes in pH, TMA and DMA occurred during 21 days storage at either temperature. TMAO decreased more during storage at-3°C than at 0°C.

Action pattern of bacillus licheniformis alpha-amylase on ordinary, waxy, and high-amylose corn starches and their hydroxypropyl derivatives

Abstract: The action of thermally stable alpha-amylase from Bacillus licheniformis on ordinary, waxy and high-amylose corn starches and their hydroxypropyl derivatives gave distinctive patterns of malto-oligosaccharide products that were dependent on conversion time. These alpha-amylolysis patterns of the various starches were derived from high performance liquid chromatographic analyses of the oligosaccharide compositions produced at various levels of hydrolysis. The products from amylolysis at high substrate concentrations (20–30%) and elevated temperature (95°C) suggest an endo-specific hydrolysis of the amylose and amylopectin chains to give a trio product-specificity for the formation of DP5, DP3, and DP2 oligosaccharides. These results confirm and expand the studies by Saito (1973) and Nakakuki et al. (1984), who found that B. licheniformis amylase degraded a 1% solution of short-chain amylose at 40° to give mainly DP5 and DP3 oligomers. The hydroxypropyl groups on ordinary, waxy and high-amylose starch derivatives greatly hindered alpha-amylolysis, but the action patterns were essentially the same.

ANTTNUTRITIONAL FACTORS AND TOXICITY IN RAW DRY BEANS (Phaseolus vulgaris, L.) OF 12 BRAZILIAN CULTTVARS

Abstract: In the present work, the relative toxicity of 12 cultivars of raw dry beans was studied. When raw dry bean flours were given in the diets as the only source of protein the Wistar rats died within 3.8 (Goiano Precoce) to 8.4 days (Aroana). When whole seed flour was mixed with casein, strong impairment to ration utilization and animal development was observed, which was measured as loss of weigh:, decreased protein digestibility, decreased biological value and net protein utilization. A positive and significant correlation between toxicity and hemagglutination activity was established. On the other hand, antitryptic activity and tannin content did not show any correlation with the toxic effect. The deterimental effect of the lectins was evident by their interaction with the intestinal mucosa, which resulted in rupture of intestinal villii thus causing interference with absorption. These effects, when strong and prolonged, can cause the rat's death, in spite of the rat's adaptive and recovering capacity.

PARTIAL PURIFICATION AND CHARACTERIZATION OF α‐GALACTOSIDASE FROM ASPERGILLUS ORYZAE

Abstract: A crude extract of α-galactosidase obtained by fermenting Aspergillus oryzae on wheat bran was purified 35 fold by ethanol precipitation, gel filtration and ion-exchange chromatography. The final preparation was free of protease activity but contained invertase activity. The molecular weight of the enzyme was estimated as 64,000 daltons. The pH and temperature optima were 4.0 and 60°C, respectively. The enzyme was stable over the pH range 3–7.5 and at temperatures up to 55°C (pH 4.0). The Km values for p-nitrophenyl α-Dgalactopyranoside (PNPG) and raffinose were 4.0 × 10−4M and 1 × 10−2M, respectively. Divalent cations were not required for activity. More than 80% of the oligosaccharides in soy milk were hydrolyzed after 3 h at 50°C using 0.113 PNPG units/mL milk.

Immobilization of papain on an anion exchange resin by physical adsorption followed by cross linking with glutaraldehyde

Abstract: A practical method involving physical adsorption by vacuum drying of papain on Dowex MWA-1 (mesh 20–50), followed by intermolecular cross linking with 1.0% glutaraldehyde under neutral pH conditions was developed. Potassium phosphate buffer (0.1 M, pH 12.5) was better for immobilization of papain than was acetate buffer (0.1 M, pH 4.0). Nitrogen recovery was increased by increasing the reaction time with glutaraldehyde from 0.5 to 15 min and enzyme concentration from 1 to 80 mg/0.3 mL buffer/0.2 g resin. Recovery of absolute and proteolytic activities, using casein as a substrate, was increased when reaction time was increased from 0.5 to 5 min. These activities were increased in a papain concentration range of 5 mg/0.2 mL buffer/0.2 g resin to 5 mg/0.3 mL buffer/0.2 g resin and then decreased with greater volumes of buffer, ranging from 11.2 to 8.6%. Relative activity recovery was decreased with an increase in reaction time and enzyme concentration, ranging from 40.5 to 7.5% and 47.5 to 1.5%, respectively. Cysteine (0.08 M) and EDTA (2 mM) enabled more than 95% of the original activity of immobilized papain to be maintained for 2 months at 5°C; NaHSO3 and ascorbic acid inactivated immobilized papain.

Multivariate analysis of structure‐related data to explain milk clotting activity of proteolytic enzymes

Abstract: Multivariate analysis was used for investigating the relationships between milk-clotting activity and physical/chemical properties, such as CD spectra, hydrophobicity and zeta potential, of ten proteolytic enzymes measured at six different pH values. Cluster analysis of CD data and zeta potential values classified the enzymes into five groups, i.e., three active enzyme groups and two inactive enzyme groups with respect to milk clotting activity. Classification of the enzymes into three groups, i.e., enzymes with high, medium and low milk-clotting activity, was achieved by discriminant analysis after adding the ratio of secondary structure parameters to the predictor variables. Results indicated that β-sheet, β-turn and random structure features were important for milk-clotting activity.

Determination of tyramine in alcoholic and nonalcoholic beers by high performance liquid chromatography with electrochemical detection

Abstract: A simple method for the isolation of tyramine from alcoholic and nonalcoholic beers and its subsequent analysis by HPLC with electrochemical detection has been developed. Ultrafiltration of the beer followed by a cation-exchange step provided clear resolution of the tyramine peak and greatly shortened the assay time. The concentration of tyramine in the alcoholic beers ranged from 0.98 to 3.21 mg L−1 and in the nonalcoholic beers from 0.52 to 3.96mg L−1. The possible hazard of consumption of both types of beer to patients on monoamine oxidase inhibitor treatment is discussed. The application of the method to the determination in other beverages is also demonstrated.

SELECTED p‐NITROANILIDES AS SUBSTRATES FOR SENSITIVE PAPAIN ASSAY

Abstract: N-acetyl-Leu-Leu-Gly-p-nitroanilide and N-succinyl-Ala-Ala-(S-benzyl) Cys-p-nitroanilide were found to be very sensitive papain substrates, making it possible to detect 0.5 or 0.7 μg of technical papain in 1 mL of beer in a short time. This detection limit is about 10 times lower than the usual papain level used for chillproofing. The estimated kinetic constants (kcat, Km) for papain, bromelain and trypsin permit certain conclusions about papain specificity for oligopeptides, which will help to prepare even more specific p-nitroanilide substrates.