LIPID COMPOSITION OF PORK MUSCLE AS AFFECTED BY SIRE GENETIC TYPE

Lipid composition of the muscle Semimembranosus was analyzed in the offspring of five different sire genetic types: Danish Duroc (DU), Dutch Large White (LW_D), English Large White (LW_E), Belgian Landrace × Landrace (EL × LR) and Belgian Landrace (BL), all of them mated to Landrace × Large White sows. The animals sired by DU boars showed the highest intramuscular fat, nonpolar lipid and free fatty acid contents. Fatty acid composition of triglycerides was little affected by genetic type. However, the fatty acid composition of phospholipids was strongly affected, the highest monounsaturated fatty acid (MUFA) and the lowest polyunsaturated fatty acid (PUFA) percentages being found in the animals sired by BL × LR boars. On the other hand, the animals sired by BL boars, which showed the highest phospholipid content, showed the highest PUFA percentage.     

CHEMICAL CHANGES AND SENSORY EVALUATION OF CHANNEL CATFISH AS AFFECTED BY DIET, PACKAGING METHOD AND FROZEN STORAGE

Fillets from farm-raised channel catfish (Ictalurum punctatus) fed diets containing various amounts of protein were packaged by the following methods: polyvinylidene chloride (PVDC) film overwrapping, vacuum packaging with Eva bag and vacuum skin packaging. Packaged fillets were stored at —28C for 90 days. Chemical and sensory changes were determined. Neither the packaging method nor protein content of diet had a significant (p < 0.05) effect on TBA number of frozen stored catfish. No significant differences on free fatty acid content of catfish packaged in different methods were also found. However, sensory evaluation revealed that greasiness of cooked catfish decreased as toughness of fillet texture increased throughout entire frozen storage.     

THERMAL BROWNING OF TOMATO SOLIDS AS AFFECTED BY CONCENTRATION AND INHIBITORS

SUMMARY– The amount of brown color developed was always determined by reconstituting the sample to 5.6% total solids and measuring optical density (O.D.) of an acetone extract at 420 mμ. Tomato solids at concentrations of 5.6 to 98% were heated for 15 min at 95°C. The O.D. increased slowly with increasing concentration to about 50% solids. Thereafter, the O.D. increased rapidly to a peak at 95% and decreased to half this value at 98%. The effect of heating time at 55, 75 and 95°C and at 5.6 and 45% solids was studied. The browning rate was slight at the lower 2 temperatures relative to that at 95°C, and was much more rapid at the higher concentration than at single strength. Under each temperature and solids condition, the rate of browning was highest at the earlier times. The inhibition effects of pH and SO₂ were studied. Browning was at a minimum at pH 2.5. Browning could be further reduced at each pH by increasing levels of SO₂. The protective effect of acidification and SO₂ addition increased with increasing solids concentration.     

VISCOSITY AND QUALITY OF TOMATO JUICE AS AFFECTED BY PROCESSING METHODS

ABSTRACT

Quality and viscosity of tomato juice is strongly governed by mechanical and thermal abuse during processing. The effect of processing and storage duration on the viscosity and quality parameters of tomato juice was evaluated in the present work. Tomato juice was obtained by two different methods, normal method (NM) and variable method (VM), and was heated by both conventional and microwave hot break treatments. Tomato juice was evaluated for various quality characteristics including precipitate weight ratio, degree of serum separation (DOSS), Brookfield viscosity, lycopene levels, vitamin C, phenols and antioxidant activity. Changes observed in several quality parameters during storage were statistically insignificant. The methods and processing had the greatest contribution toward viscosity, whereas storage duration had no significant effects. Viscosity parameters viz precipitate weight, DOSS and Bostwick consistency revealed that juice processed by VM was more viscous than that of NM, irrespective of the hot break processing used. Ascorbic acid and lycopene content varied significantly with mechanical methods and processing conditions. However, phenolic content and antioxidant activity remained stable. The variable process represents an improvement over the conventional by enabling tomato processors to improve the consistency of the tomato product.

PRACTICAL APPLICATIONS

Quartering or slicing tomatoes followed by hot break processing techniques can significantly improve the quality of tomato juice in terms of reduced degree of serum separation and precipitate weight ratio. The modified technology could be considered as a viable and economical method for small‐ and medium‐scale tomato processors with limited resources and facilities at their disposal.

     

RHEOLOGY OF APPLE AND POTATO TISSUE AS AFFECTED BY CELL TURGOR PRESSURE

Experiments were performed on two varieties of apple tissue and one variety of potato tissue, in which cell turgor pressure was varied and the concomitant mechanical properties of the tissue were tested. Turgor pressure was controlled by immersion in solutions of various mannitol concentrations, and the degree of swelling or contraction of the tissue samples was measured. Under constant-strain-rate loading, mode of failure varied among the different commodities, and underwent a transition as the turgor pressure was varied. Rate of loading also caused a transition in failure mode. The stress and strain at failure and tissue stiffness were related to mode of failure, turgor pressure, and strain rate. From the osmotic swelling data, estimates were made of the cell wall stress-strain behavior and of the probability distribution for cell-wall strength in Ida Red apple tissue.     

BUTTER STABILITY AS AFFECTED BY EXTRACTS OF SAGE, ROSEMARY AND OREGANO

Effects of methanolic extracts of sage ( Salvia fruticosa L.), rosemary ( Rosmarinus officinalis L.) and oregano ( Origanum vulgare L.) on butter stability were investigated. All extracts were individually added to butter at 0.02 or 0.05%. For comparison, 0.02% butylated hydroxyanisole (BHA) and control group were also prepared and tested. The samples were stored at 25 or 5C. The peroxide value, free fatty acids and thiobarbituric acid value were determined at regular intervals for all samples. Spice extracts and their combinations exhibited a better effect than that of BHA in stabilizing butter against oxidation. The most effective extract was that of sage. The extracts significantly stabilized butter (P<0.05). Butter samples stored at 5C were more stable (P<0.05) than those kept at 25C.     

A RESEARCH NOTEE CHEMICAL, PHYSICAL, AND SENSORY CHARACTERISTICS OF COLOR MODIFIED PORK AS AFFECTED BY DIAMINOCYCLO-HEXANE-TETRACETIC ACID MONOHYDRATE

Restructured pork chops were manufactured from ground pork shoulders that had been color modified by washing with phosphate buffer solutions, color modified with the addition of diaminocyclo-hexane-tetraacetic acid monohydrate (CDTA), or not color modified as a control. Proximate analysis, cooking loss, pH, sensory traits, color (subjective and objectivee, and TBARS were evaluated. Color modified washed samples without CDTA had higher (P<0.05) pH and moisture content and lower (P<0.05) percentage protein and cooking loss than the control treatment. There was no difference (P>0. 05) between control and color modified products for sensory traits. These traits did not change from 1 to 10 days except for favor intensity which decreased for the color modified product. Thiobarbituric acid reactive substances (TBARS) values revealed that the washed product did not become rancid with or without CDTA, until after 10 days of display; whereas, the control was rancid the first day. This modification produced a lighter colored (P<0.05) product that is less vulnerable to rancidity.