Reduction of Bitterness and Tartness in Grapefruit Juice with Florisil

Treatment of commercial grapefruit juice with Florisil (activated magnesium silicate) simultaneously reduced the content of citric acid and the bitter compounds limonin and naringin. Ascorbic acid concentration and °Brix (total soluble solids) were not altered by the Florisil treatment. Experienced taste panelists were able to differentiate between the nontreated and Florisil-treated juice on the basis of bitterness and tartness (acidity). The panelists indicated a preference for the Florisil-treated juice.     

Mechanically Separated Spleen: Its Composition and Protein Efficiency Ratio

Beef spleens were freed of undesirable capsular and internal connective tissue by passage through a Beehive Model AU 4171 deboner fitted with a desinewing head. The resulting product (called mechanically separated spleen or MSS) was recovered at a 79% yield and contained 17.0% protein, 2.9% fat and 762 ppm iron. The effect of mechanical separation on protein quality was determined by protein efficiency ratio (PER). Rats fed MSS and whole spleen diets exhibited significantly greater weight gains than those fed casein. PER values for whole spleen (2.4) and MSS (2.3) were not significantly different. The PER value for casein (2.5) was significantly higher than that of MSS but not whole spleen.     

Mushroom (Agaricus bisporus), Its Polyphenoloxidase, and Polyphenolics Affect In Vitro Iron Availability

In vitro iron availability (IA) from egg white meals was 14–17% of total meal iron. When mushroom (Agaricus bisporus) was added to egg white meals, IA decreased. The initially low IA from whey protein concentrate meals (<1% of meal iron) was enhanced by mushroom. Sodium benzoate or sodium bisulfite added to egg white/ mushroom meals increased IA. Addition of polyphenoloxidase (PPO) and gallic acid to egg white meals decreased IA; however, gallic acid alone increased IA. Blanching mushrooms eliminated PPO activity and increased IA of egg white/mushroom meals, but it was still less than for egg white meals. Sodium bisulfite added to blanched mushroom/egg white meals increased IA above that for egg white meals. Results are consistent with the interpretation that enzymatic browning can decrease IA.     

External Fat Cover Influence on Raw and Cooked Beef. 1. Fat and Moisture Content

SUMMARY: The fat content of beef semitendinosus muscle, raw and cooked at two oven temperatures, with and without the external fat cover, has been determined. Each muscle was divided into two, an anterior and a posterior roast. The external fat cover was removed from half of the total number of roasts, and all roasts were then cooked to an internal temperature of 58°C at an oven temperature of either 163° or 218°C. Two types of samples were analyzed for their moisture and fat content. These were a separable lean sample and a total sample. The total sample was composed of both the separable lean and the external fat cover. The moisture content of the lean samples was not affected by the oven temperature, the external fat cover or the end of the muscle used. The total samples had moisture contents that reflected the amount of crude fat present. The yield of crude fat from raw or cooked meat was not significantly altered by the use of a polar solvent in place of a nonpolar one. Both of the fat determination methods extracted significantly more fat from the cooked lean samples than from the comparable raw ones. The lean samples from meat roasted at 163°C contained significantly more extractable fat than the samples roasted at 218°C. The presence or absence of the external fat cover did not affect the amount of fat extracted from the cooked lean.     

Isoelectric Focusing Evidence for Banana Isoenzymes with Mono and Diphenolase Activity

Isoelectric focusing on thin layers of Sephadex G-75 superfine gel followed by the print technique was used to investigate the presence of polyphenol oxidase isoenzymes in banana fruits. The enzyme preparation from pulp tissues of unripe “Dwarf Cavendish” bananas, partially purified by (NH₄)₂SO₄ fractionation, revealed 14 isoenzymes having both monophenolase (p-cresol substrate) and diphenolase (dopamine or catechol substrate) functions with isoelectric points (pi) in the pH range 4—5.5. Similarly, two strains of the cv “Red Skin” showed 10 and 13 isoenzymes with pi in the pH range 4–5.8, most of which were capable of hydroxylation of monophenols. Individual isoenzymes exhibited variations in their activity towards mono and odiphenols.     

The chemical and sensorial effects of lysozyme addition to red and white wines over six months' cellar storage

Lysozyme is an enzyme with muramidase activity which can lyse Gram-positive bacteria, including wine lactic acid bacteria. This enzyme provides a practical method for delaying or preventing the growth of Oenococcus oeni and consequently the onset of malolactic fermentation during the vinification of red and white wines. This paper reports the impact of lysozyme on the chemical and sensorial properties of commercially vinified red (Cabernet Sauvignon and Shiraz) and white (Riesling) wines. The addition of lysozyme to these wines had little or no effect on the content of alcohol, free and total sulfur dioxide and titratable acidity, and pH value. The lysozyme retained 75–80% activity in the Riesling wine after six months, however no detectable activity remained in the Cabernet Sauvignon and Shiraz wines after two days. Upon addition of lysozyme to both of the red wines, a rapid initial decrease (up to 17%) in red wine colour density and phenolic content occurred in association with the formation of a light precipitate. The reduction in red wine colour was also noted by the sensory panel. When added to the Riesling wine, lysozyme did not cause an increase in browning over the six month storage time, but did induce heat instability (haze), suggesting that white wines may require protein stabilisation following treatment with lysozyme. Sensory assessment by triangle difference testing revealed that, during the six month storage period, treatment with lysozyme did not cause important changes to either the aroma or palate of the red and white wines tested.     

QUALITY OF MEAT PRODUCTS DURING REFRIGERATED AND ULTRA-CHILLED STORAGE

Standard domestic refrigerators store food between 1 and 5C (33.8–41F). A manufacturer recently developed a refrigerator capable of storing food in the “ultra‐chilled region” (?3 to ?7C) and claimed that storage of fresh meat in this region better maintains quality. To understand quality in terms of chemical reaction rates, microbial growth and texture and flavor changes, three common consumer meat products – steak, ground beef patty and salmon – were stored for a selected period of time, as determined by microbial testing, in five refrigerator models with different environmental conditions (constant temperature and temperature fluctuation). At the end of the storage period, consumer panelists assessed the quality of the cooked samples by ranking them according to preference. In addition, instruments were used to measure the color and shear cutting force (for steak only) of each sample. Results from the consumer Ranking R‐Index Test indicate that panelists preferred samples stored under or near ultra‐chilled conditions rather than samples stored under standard refrigerated conditions. The ultra‐chilled samples not only had higher panelist rankings and more favorable comments, but also had lower microbial aerobic plate counts. The instrument readings, however, highly varied and did not correlate well with sensory data.     

VISCOMETRIC MEASUREMENT OF CHROMIUM(III)-POLYACRYLAMIDE GELS†

Gelled polymers are being used increasingly to modify the movement of injected fluids in secondary and enhaced oil recovery processes. A common gelation process involves the reduction of Cr(VI) to Cr(III) in the presence of polyacrylamide. The Cr(III) reacts or interacts with the polymer to form a gel network. Although correlations of gelation time with principal process variables have been obtained, viscometric data have not been reported during or after gelation. These data are needed for fluid flow calculations in surface equipment and estimation of flow behaviour in reservoir rocks.

A Weissenberg Rheogoniometer, with cone and plate geometry, was used to obtain viscometric data for the gelation of polyacrylamide and chromium (III). Solutions consisting of polyacrylamide polymer, sodium dichromate-dihydrate and sodium bisulfite were gelled under a steady shear field at constant temperature. The shear stress versus time profile for the galation process was interpreted to define a gelation time and to determine the apparent viscosity of the gelled fluid. The gelation time decreased as the applied shear rate increased up to about 14.25 sec^?1 and was affected by shear rate history. Viscometric properties of the gelled solutions were determined. Apparent viscosity of the gelled solutions decreased as the shear rate under which they were formed increased.

Post gelation studies indicated that gels exhibited a residual stress at zero shear rate and behaved as Bingham plastics under steady shear. Gels formed at low shear rates were more viscous than gels formed at high shear rates. However, the structure of these gels was susceptible to shear degradation.     

Methods used to study non-starter microorganisms in cheese: a review

The significance of non-starter lactic acid bacteria (NSLAB), which become the dominant organ-isms in hard cheese varieties during ripening, is still controversial, but they have been shown to contribute to the release of amino acids and to influence flavour development. Since the NSLAB population is essentially uncontrolled, it is likely that at least some of the variability in cheese quality is due to the NSLAB. Several approaches used to assess the significance of NSLAB in cheese ripening are reviewed in this paper.