P. E. Koehler

Four-factor response surface optimization of the enzymatic modification of triolein to structured lipids

The ability of an immobilized lipase to modify the fatty acid composition of (88.8% C18:1, 4.3% C16:0, 3.1% C18:0, and 3.8% C18:2 as determined by gas chromatography, and approximately 90% triolein) in hexane by incorporation of a medium-chain fatty acid, capric acid (C10), to form structured triacylglycerol was studied. Response surface methodology was used to evaluate the effect of synthesis variables, such as reaction time (12–36 h), temperature (25–65°C), molar substrate ratio of capric acid to triolein (2:1–6:1), and enzyme amount (10–30% wt% of triacylglycerol), on the yield of structured lipid. Optimization of the transesterification was attempted to obtain maximum yield of structured lipid while using the minimum molar substrate ratio and enzyme amount as much as possible. Computer-generated contour plot interpretation revealed that a relatively high molar substrate ratio (6:1) combined with low enzyme amount (10%) after 30 h of reaction at 25°C gave optimum incorporation of capric acid. A total yield for combined monoand dicaproolein of up to 100% was obtained.

Regulation of Growth and Pigmentation of Monascus Purpureus by Carbon and Nitrogen Concentrations

Growth and pigment production of Monascus purpureus were affected by the ratio of glucose to ammonium nitrate concentration in a synthetic medium. Mycelial growth increased with an increase of gluc...

Tocopherols in runner and Virginia peanut cultivars at various maturity stages

Alpha-, beta-, gamma-, and delta-tocopherol (α-T, β-T, γ-T and σ-T) were determined in peanut (Arachis hypogaea L.) cultivars Florunner, Sunrunner, Southern Runner, AT-127, GK-7, NC-7, NC-9 and GK-3. There were significant differences in tocopherol content among runner- and virginia-type peanut cultivars, and these differences were affected by the degree of maturation. α-T decreased with maturation for all of the cultivars except Florunner. γ-T increased with maturation for GK-7, NC-9 and GK-3 but decreased for Florunner. For the mature nuts, Florunner and NC-9 had the highest levels of α-T while GK-3 and Southern Runner had the lowest levels. GK-7 and Sunrunner had the highest levels of γ-T, while the lowest levels were in Florunner and GK-3.

Formulation and optimization of sucrose polyester physical properties by mixture response surface methodology

The physical properties of sucrose polyester (SPE), prepared from different composite blends of fatty acid methyl esters (FAME) of safflower oil, palm oil, and peanut oil, were evaluated by mixture response surface methodology. Optimum combinations of fatty, acids to achieve specific physical properties of SPE were determined. The SPE most similar in physical properties to peanut oil was obtained with a 55:45 molar ratio of mixed FAME from safflower oil and peanut oil. The physical properties of SPE were significantly affected by the degree of saturation and the average chainlength of their composite fatty acids.

Differentiation in Aspergillus flavus as influenced by L-canavanine.

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Aflatoxin B1—Effects on rainbow trout liver chromatin☆

Abstract Injection of 400 μg/kg doses of aflatoxin B 1 into the Virginia strain of rainbow trout resulted in quantitative changes in the protein/DNA ratio of liver chromatin. Ammoniacal-silver staining indicated a 41 per cent loss of chromatin stainability. A 65 per cent total loss of histone and acidic proteins, relative to DNA, was observed by direct measurement of extracted and fractionated chromatin. Losses of chromatin protein were restored within 48 hr after injection.

Fluorometric measurement of aflatoxins.

An accurate, precise and sensitive fluorometric method for quantifying purified aflatoxins in solution is proposed. After purification, aflatoxin samples are read in a fluorometer with a primary filter of 365 nm and a secondary filter of 435 nm for B1 and B2 and 465 nm for G1 and G2. The method is precise at as little as 0.0002 µg/ml B1 and G1 and 0.00006 µg/ml B2 and G2, and accurate at concentrations of 0.002 µg/ml B1 and G1 and 0.0006 µg/ml B2 and G2.