E. T. Rayner

Inactivation of aflatoxins in peanut and cottonseed meals by ammoniation

Aflatoxins in peanut and cottonseed meal can be inactivated by treatment with gaseous ammonia. In pilot plant runs, contaminated peanut meal was ammoniated at two levels each of moisture content, reaction time, temperature and ammonia pressure. Thin layer chromatography indicated that ammoniation inactivated the aflatoxins (121 ppb) in the meal to a nondetectable level. With a similar treatment, total aflatoxins (350 ppb) in cottonseed meal were reduced to 4 ppb. A series of runs was made with large scale equipment using cottonseed meal containing an average of 519 ppb total aflatoxins. Under optimum processing conditions, aflatoxin content of this meal was reduced to below 5 ppb and non-detectable levels.

Novel technique for the analysis of volatiles in aqueous and nonaqueous systems

A simple, efficient, external inlet assembly is described for analyzing volatile components in raw and processed foods by direct gas chromatography and mass spectrometry. The device comprises three sections: a sample inlet, a condenser, and a six-port rotary valve. The versatility and effectiveness of this assembly is demonstrated by the analysis and identification of volatiles from diverse food products as salad oils, vinegar, and corn-soy food blends. The procedure is rapid, efficient, and offers the following desirable features: it is compatible with all commonly used chromatographs and can accomodate samples of different size; sample volatiles are obtained without use of prior enrichment techniques, at ambient or elevated temperatures; uniform heating enhances volatiles elution, thereby improving sensitivity; moisture and air are removed to facilitate mass spectral analysis; the closed nature of the system minimizes loss of low molecular weight volatiles during elution, thus producing a highly reliable pro-file of volatiles.

Analysis of vegetable oils for flavor quality by direct gas chromatography

Abstract and SummaryRecently, a direct gas Chromatographic method for examining volatiles in vegetable oils was reported [Dupuy et al., JAOCS 50:340 (1973); and Dupuy et al., Ibid. 53:628 (1976)]. The procedure stimulated the development of instrumental techniques for determining odor and flavor characteristics of vegetable oils. This symposium paper describes modifications of the original direct gas Chromatographie procedure that substantially enhance its sensitivity and applicability. Profiles of volatiles for several experimental oils obtained by the modified system are presented, together with mass spectral data characterizing significant flavor-related peaks. Regression analysis of the instrumental data, with oil flavor scores, indicates that reliable flavor characteristics of high- and low-quality vegetable oils may be obtained rapidly and efficiently by instrumentation.

Correlations of flavor score with volatiles of vegetable oils

A simple, direct, gas chromatograph (GC) technique is described for eluting flavor-related volatile components from commercially produced vegetable oils. A sample of oil was placed onto glass wool contained in a GC liner, and the liner was inserted in the heated inlet of the GC. Volatiles from the oils were rapidly eluted by heat and carrier gas onto the GC column. Profiles of the volatiles were obtained by temperature-programmed gas chromatography. Flavor score was highly correlated with individual volatile components considered separately, and very highly correlated with multiple volatile components considered together, indicating that reliable flavor characteristics of vegetable oils may be obtained rapidly and efficiently by instrumentation.

DETERMINATION OF RESIDUAL SOLVENT IN OILSEED MEALS AND FLOURS BY A VOLATILIZATION PROCEDURE

A simple volatilization procedure was developed for the determination of residual hexane in oilseed meals and flours. A 2 g sample of meal or flour and 0.2 g of water are weighed into a 120 ml serum bottle, which is sealed and heated at 110 C for 2 hr in an oven. A 1 ml aliquot of the head-space gas is then analyzed by gas chromatography. The concentration of residual hexane is easily determined by comparing the area of the appropriate peak of the chromatogram with a calibration chart. Results are reproducible within ±20%, and concentrations as low as 1 ppm can be detected. The technique is much simpler and more efficient than other procedures available. It also appears to be useful for determining other residual solvents such as acetone and isopropanol, and acetone impurities such as mesityl oxide and diacetone alcohol in oilseed meals and flours.

Removal of aflatoxins from oilseed meals by extraction with aqueous isopropanol

Aqueous isopropanol was found to be an effective solvent for removal of aflatoxins from contaminated cottonseed and peanut meals. Extraction with 6 passes of 80% aqueous isopropanol at 60C resulted in complete removal of aflatoxins in both meals, as measured by thin-layer chromatography. Under similar extraction conditions, the isopropanol-water azeotrope, 88% isopropanol by weight, removed 88% of the total aflatoxins in peanut meal, a reduction from 82 to 10 ppb, and 79% of the total aflatoxins in cottonseed meal, a reduction from 214 to 46 ppb. Lower temperatures were less effective with both solvent systems.

Determination of residual solvent in oilseed meals and flours: IV, acetone

A simple volatilization procedure was developed for the determination of residual acetone in oilseed meals and flours. One gram of meal or flour and 0.2 g of water containing 0.4 mg of methanol are added into a 100 ml serum bottle, which is sealed and heated at 70 C for 5 hr in an oven. A 1 ml aliquot of the headspace gas is then analyzed by gas chromatography. The concentration of residual acetone is easily determined by comparing the ratio of the peak areas of acetone to methanol of the chromatogram with a calibration curve. Results are reproducible within ± 10%, and concentrations of a few ppm can be detected. This technique is much simpler and requires less operator time than other procedures available.

Analysis of flavor quality and residual solvent of soy protein products

A simple, direct, gas Chromatographic technique is described for eluting and resolving residual solvent and flavor-related volatile components from soy products such as flour and protein isolates. No prior enrichment of volatiles is necessary. A sample, together with a small amount of water, is secured in a glass liner and placed in the heated injection port of a gas Chromatograph. The volatiles are rapidly steam distilled from the sample by the heat, moisture, and flow of carrier gas and are adsorbed on the chromatographic column in situ. Residual solvent and other volatiles adsorbed on the column are resolved by temperature-programmed gas chromatography and identified by combined gas chromatography-mass spectrometry. The correlation between taste panel flavor score and concentration of volatile components is significant at the 1% level.

Solvent extraction of aflatoxins from contaminated agricultural products

Abstract and SummarySolvent extraction of agricultural products has been suggested as an effective means of removing aflatoxins from mold-damaged commodities. The use of various polar solvents such as the azeotrope of acetone-hexane-water and of 2-propanol-water, aqueous acetone, and aqueous ethanol has been reported in the literature. This paper examines the overall aspects of solvent extraction, in particular the use of the azeotrope of 2-propanol-water, to remove aflatoxins from prepress solvent extracted cottonseed meal.

Rapid quantitative determination of residual hexane in oils by direct gas chromatography

A simple, direct, gas chromatographic technique is described for the quantitative determination of residual hexane in extracted vegetable oils. The method if rapid and sensitive to one ppm hexane. The inlet liner of a gas chromatograph was packed with 1 1/2 in. glass wool, and 25 mg oil was added onto it. The sample was capped with a small plug of glass wool, and the liner was inserted in the heated inlet of the gas chromatograph. Residual hexane rapidly eluted onto the Poropak P column by heat, and carrier gas was resolved in 20 min by temperature programing between 70–180 C. The method appears useful for monitoring continuous solvent removal processes.