ALUMINUM STABILIZES TURMERIC IN PICKLE BRINE AGAINST DECOMPOSITION BY LIGHT,HEAT AND PEROXIDASE1

Turmeric in solutions typically used for cucumber pickle manufacturing was protected by Al³⁺ from decomposition caused by fluorescent light, heat and peroxidase. Levels of 1.3–1.5 mM Al³⁺ significantly reduced light-and peroxidase-catalyzed decomposition of turmeric, and the amount of retardation increased with increasing Al³⁺ concentration. Alone, neither peroxidase nor hydrogen peroxide affected turmeric; however when combined, turmeric was rapidly destroyed. Peroxidase destruction of turmeric was uncompetitively inhibited by Al³⁺. Turmeric decomposition increased with increasing temperature from 20 to 90°C. No thermal destruction of turmeric was observed in the presence of 2 or 4 mM Al³⁺.     

LIPID OXIDATION OF FISH LIVER OIL AS AFFECTED BY LIGHT, ANTIOXIDANTS AND TEMPERATURE

Crude and refined Mackerel liver oil with or without antioxidants were stored in artificial light or in darkness to assess the effects of photo-oxidative stress on the stability of oils and the antioxidant activity of butylated hydroxy-anisole (BHA) and tert-butylhydroquinone (TBHQ) on those oils. Changes in peroxide value (PV) and thiobarbituric acid value (TBA) were monitored over 18 days at 5C and 40C. The results showed that visible light exposure played the most critical role in the acceleration of fish liver oil oxidation. The addition of antioxidants showed a significant effect in retarding oxidation with TBHQ more effective than BHA. The oxidation rate of the oils decreased in the following order: control with light > control + BHA with light > control without light > control + TBHQ with light > control + BHA without light > control + TBHQ without light. Higher PV and TBA values were observed in refined oils versus crude oils. Increasing storage temperature accelerated the oxidation of only refined oils in light.     

METABOLISM OF SOLANINE AND CHLOROPHYLL IN POTATO TUBERS AS AFFECTED BY LIGHT AND SPECIFIC CHEMICALS

SUMMARY— Chlorophyll and solanine syntheses as affected by cultivars, specific gravities, light intensities, and chemicals were studied in potato (Solanum tuberosum, L.) tubers. When exposed to 100 ft-c of while fluorescent light for 5 days, tubers of Bounty, Kennebec, Norchip and Red Lasoda were most sensitive to greening and solanine development. LaChipper and Platte tubers were resistant to the light effects. Chlorophyll synthesis was inversely related to specific gravity of tubers, while specific gravity did not affect solanine synthesis. The chlorophyll content of tubers exposed to 50 ft-c and 200 ft-c was significantly less than that of tubers exposed to 100 ft-c and 150 ft-c light intensities. The solanine synthesis was not influenced by the light intensities studied. Chemicals were applied at a concentration of 10,000 ppm by vacuum injection technique. Ethrel® and Alar® were effective in inhibiting chlorophyll and solanine formation. Ethrel was more effective in retarding the chlorophyll formation and alar was most effective in preventing solanine formation. Maleic hydrazide MH®-30 and Cyocel® were ineffective in controlling both chlorophyll and solanine formation.     

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.     

THE THERMAL PROPERTIES OF POTATOES AND CARROTS AS AFFECTED BY THERMAL PROCESSING1

The effects of processing on the thermal properties of white potatoes and carrots were studied. The test samples were blanched, boiled, cooked and canned. Whole potato tubers were baked to study the effects of starch gelatinization. The thermal conductivity (k) and density (ρ) were measured and the specific heat (c_p) and thermal diffusivity (α) were calculated. Results showed that in general, α initially decreased and then increased during processing. Test samples were found to have a gain in α when their moisture content increased by more than 9%. The α of potatoes decreased after canning and increased after boiling. In carrots, a similar trend was also observed but to a lesser degree. The k of potatoes was unaffected after blanching or cooking. In all the processing baking study showed that gelatinization significantly decreased the k of potatoes.     

THERMO-RHEOLOGICAL PROPERTIES AND COOKING YIELD OF SAUSAGE-TYPE PRODUCTS AS AFFECTED BY LEVELS OF FAT AND ADDED-WATER1

Consumer interest in low fat foods has led meat processors to introduce low fat sausages with high added-water. The purpose of this study was to use dynamic thermo-rheological techniques to study the influence of fat and added water on sausage batters and cooking yields during heating. Twenty different sausage batters were formulated to 15–30% fat and 18–35% added water. Batters were heated in a thermal scanning rheometer from 20–80C in increments of IC/min. Rheograms of all batters showed a gradual decrease in storage modulus (G') as temperature increased from 20–59C. Significant changes in G' occurred in the range of 60–75C leading to the formation of rigid gel networks. Batters with levels of fat ≤ 24% and added water > 24% or levels of fat and added water ≥ 27% showed increased cooking yields. Rheological measurements suggested that levels of added water influenced the G' of batters during heating and that high levels of added water could be used in sausage formulations without adversely affecting product yield.     

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.     

CHEMICAL COMPOSITION OF TOMATOES AS AFFECTED BY MATURITY AND FERTIGATION PRACTICES

The objective of this study was to determine the effect of various fertigation practices and maturity stages on tomato fruit composition. Soluble solids, reducing sugar content, and sugar/acid ratio of tomatoes increased with maturity. Fertigation treatments had less of an effect on the chemical composition of the fruit than the stage of maturity. Mineral (P, K, Ca, Mg) levels of tomato fruits in fertigated treatments were higher than in the control plot treatments receiving no supplemental water during the production season. Ascorbic acid content in whole mature-red fresh tomatoes was 13.24% and 25.71% higher than that in mature-pink and mature-light pink tomatoes, respectively. The locule section contained more ascorbic acid than other parts of the fruit at maturity. Intensive mineral fertigation and harvesting at the ripe stage contributes toward higher nutritional quality in fresh tomatoes.     

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.     

ENZYME ACTIVITY AND QUALITY OF FROZEN GREEN BEANS AS AFFECTED BY BLANCHING AND STORAGE

Effects of different blanching conditions on residual enzyme activities and quality changes in green beans during frozen storage were studied. Green beans were blanched at various temperature and time combinations at both pilot plant and commercial scales. After storage at —23°C for 3, 6, 9 and 12 months they were analyzed for residual activities of catalase, lipoxygenase, polyphenoloxidase and peroxidase; changes in sensory quality as evaluated by a taste panel; and color and firmness as measured with instruments. Most of enzymes were inactivated during normal blanching but the residual activities varied among enzymes. Beans blanched above 82°C for 3.5 min yielded higher sensory scores for the quality attributes tested than those blanched at the lower temperatures. However, there appears to be no direct relationship between the quality attributes measured and the residual enzyme activities during 12 months storage.     

EGG QUALITY AS AFFECTED BY STORAGE AND HANDLING METHODS

The quality and shelf-life of fresh eggs were studied under simulated climatic conditions as found in Kuwait. Three groups of eggs (unwashed, washed, and washed and oil treated) were used. The treated eggs were stored at 5°, 25°, 37° and 42°C. Internal and external quality and sensory evaluation of the eggs stored up to 75 days were determined. The quality of the unwashed and washed eggs stored at 37°C and 42°C deteriorated rapidly while the wash and oil treatment extended shelf-life but decreased in quality to C over a period of time. The percent weight loss in the oil treated eggs at all temperatures was about 0.6% while the washed and unwashed lost more depending upon the temperature and storage time. All parameters studied for interior quality showed that oil treated eggs were significantly better than untreated eggs even at 42°C. Sensory evaluation on boiled eggs indicated that changes in flavor and overall quality for untreated eggs stored at high temperatures were obvious while little change in texture was observed. It was concluded that under Kuwaiti conditions eggs should be oil treated directly after collection and stored at or below 25°C so that the quality and shelf-life can be extended significantly.     

SMALL FRUIT QUALITY AS AFFECTED BY POINT OF ORIGIN-DISTANT VERSUS LOCAL1

Small fruits shipped into local markets from major production areas 800 to 2400 km distant were compared to small fruits grown within 25 km of this location. Fruits were evaluated for acceptability of flavor, texture, color, instrumental color (Hunter Color Difference Meter‘L’,‘a’,‘b’, hue, and chroma), shear press firmness, weight loss, dry matter, soluble solids, acidity, mineral content (Ca, Mg, Na, K, P), protein, and Vitamin C (strawberry only) after holding for 0, 2, or 4 days (strawberry); 0, 3, or 5 days (grape); or 0, 3, 5, or 7 days (blueberry) at 21°C. Distant-grown small fruits were nutritionally comparable to those grown locally but generally inferior in overall sensory attributes, particularly taste. There were no real disadvantages observed that would detract from the marketing of these locally produced small fruits.