Walter A. Pons

Determination of free gossypol in cottonseed materials

SummaryA method for the determination of free gossypol in cottonseed materials is described. The method consists of extraction of gossypol with a measured volume of 70% aqueous acetone on a shaker for one hour, filtration, and colorimetric analysis for gossypol in an aliquot of the filtrate by means of the reaction between gossypol andp-anisidine.The conditions for complete extraction of gossypol from various types of cottonseed materials have been investigated, the stability of gossypol in aqueous acetone has been demonstrated, and data are presented on recovery of gossypol added to cottonseed materials. The method has been compared with the method of Smith (2).

Objective fluorometric measurement of alfatoxins on TLC plates

Measurement of the solid state fluorescence of aflatoxins on silica gel-coated TLC plates on a densitometer equipped for fluorescence measurements showed a linear relationship between peak areas and concentration over a range of at least 2 to 105×10−4 μg of aflatoxins per spot. Response of individual aflatoxins was in order of B2>G2>B1>G1. Aflatoxins can be measured with a precision of ±2–4%.

AQUEOUS ACETONE EXTRACTION OF COTTONSEED

Extraction of cottonseed flakes with acetone containing 25-30% water removes essentially all of the gossypol, most of the free fatty acids, about half the raffinose, and negligible quanti-ties of neutral oil and protein. After drying and re-flaking of the aqueous acetone extracted marc, the oil may be removed either by hexane extrac-tion or pressing to produce light-colored meals exceptionally low in gossypol pigments, high in protein and available lysine content. Crude oils are light-colored, contain negligible amounts of gossypol, are high in neutral oil content, and re-fine and bleach to a prime color value. The pro-cess is effective for the removal of such toxic mold metabolites as aflatoxins from mold-damaged seed.

Prepress-solvent extraction of cottonseed, processing conditions and characteristics of products

SummaryA study has been made of the relation between processing conditions and the chemical characteristics of cottonseed meals and oils produced by prepressing-solvent extraction. Twenty-six complete sets of mill samples of known processing history and representative of the production at 11 mills were used in the investigation.Cooking conditions were the major factor influencing the distribution of the gossypol between the meal and oil. Reduction in free gossypol during cooking was due to binding with meal components while that occurring during prepressing and solvent extraction resulted mainly from removal of gossypol in the prepressed and solvent-extracted oils.Nitrogen solubility data, which have been suggested as a measure of protein damage, indicated that the major change or reduction in nitrogen solubility occurred during cooking. Very little reduction was noted for prepressing or solvent extraction. The reduction in nitrogen solubility during prepressing is much smaller than that previously reported for normal screw-pressing operations.Prepressed oils gave lower refining losses and lower refined and bleached color than did the solvent-extracted oils. Bleach color reversion, after storage of crude oils for 30 days at 100°F., was greater for solvent-extracted than for prepressed oils.A number of meals exhibited the desirable characteristics of low free gossypol content and high nitrogen solubility. Values calculated for chemical indexes of protein quality, as suggested by Lyman and associates (11), indicate that many of the meals should have good protein quality.

Kinetic study of acid-catalyzed conversion of aflatoxins B1 and G1 to B2a and G2a

Adjusting dilute aqueous solutions of aflatoxins B1 and G1 to pH 1, 2 and 3, and heating over a range of 40–100 C resulted in the conversion of B1 to B2a and G1 to G2a as major products. Both B2a and G2a were identified by co-thin layer chromatography with authentic B2a and G2a and M1 on silica gel plates developed in two different solvents. The rate of disappearance of B1 or G1 at given temperature and at constant pH was found to be first order with respect to each aflatoxin. At given temperature the conversion is strongly pH dependent, a 10-fold increase in H+ ion (1 pH unit) producing about a 9-fold increase in the reaction rate, indicating first order dependent of the rate on H+ ion concentration.

Relationship of physical appearance of individual mold-damaged cottonseed to aflatoxin content

Abstract and SummaryOver 700 individual aflatoxin-suspect cottonseed were hand-selected from a heterogenous stockpile of ginned seed. The seed were categorized on the basis of (a) bright greenish-yellow, fluorescence termed cateye, on the linter fibers under ultraviolet light; (b) partially bald seed with part of the linter fibers removed by ginning; (c) a combination of cateye and balding; (d) thin and discolored lint; and (e) bluish, not cateye, fluorescence. Aflatoxin assays on each of the 771 selected seed showed that 142 out of 771 (18%) were contaminated by aflatoxin (B1+B2) in the range of 150 ppb—5.75 million ppb. Some 93% of the aflatoxin-contaminated seed was concentrated in categories (a), (b), and (c), with the highest concentration, 61%, in category (b). Eight seed in these three categories contained over 1 million ppb of aflatoxins. The data suggest that removal of cateye and partially bald seed from contaminated lots of cottonseed should be more effective for controlling aflatoxin contamination in cottonseed than removal of cateye seed alone.

Physiological evaluation of solvent-treated cottonseed meals in rations for laying hens.

Two commercial cottonseed meals, a direct solvent-extracted meal and a screw-pressed meal, were subjected to successive solvent-extraction procedures by using an acetone/hexane/water azeotrope to reduce their cyclopropenoid fatty acid content. The two original commercial meals, as well as a double- and triple-extracted portion, were then incorporated at 20 wt % levels in the rations of laying hens. A negative control containing 25% soybean meal and a positive con-trol containing 2 % refined cottonseed oil of known CPA content were also employed. During a four-week feeding period the eggs were collected dur-ing the third and fourth week and stored at 35F for periods of three and six months. Over-all egg quality and the fatty acid distribution of the extracted yolk lipids were determined after the three- and six-month storage period.

Separation of aflatoxin-contaminated cottonseed based on physical characteristics of seed cotton and ginned seed

Abstract and SummarySamples of aflatoxin-contaminated stored ginned cottonseed and of freshly harvested seed cotton and companion ginned seed were examined under long wave ultraviolet (UV) and visible light to develop physical criteria for separating aflatoxin-contaminated seed from sound seed. Seed locks characterized by bright greenish-yellow, or cateye, fluorescence when viewed under long wave UV light were separated from samples of 12 varieties of freshly harvested seed. As a result, 80–100% (mean 96%) of the aflatoxin contamination that was concentrated in 2–9% (mean 6%) of the seed weight was effectively removed. The cateye fluorescence separation technique was slightly less effective for removing aflatoxins from companion freshly harvested, ginned samples, but most of the aflatoxins were concentrated in only 0.5–3% (mean 2%) of the seed weight. This approach was relatively ineffective for stored ginned seed, probably due to deterioration of the cateye fluorescence.

Determination of aflatoxins in peanut and cottonseed soapstocks.

An accurate and sensitive procedure is proposed for estimating aflatoxins in both alkaline and acidulated soapstocks. Sample suspensions in aqueous acetone are adjusted to pH 3 with hydrochloric acid, extracted in a high speed blender, treated with lead acetate and partitioned into chloroform. After silica gel cleanup, aflatoxins in purifie extracts are estimated by thin layer chromatography. The use of acetone and lead acetate together apparently catalyzes the relactonization of flatoxins B1 nd G1 and leads to essentially quantitative recovery of aflatoxin B1 and somewhat lower recovery of G1 added to alkaline or acidulated soapstock.

Chemical inactivation of cyclopropenoid fatty acids in cottonseed meals and their physiological evaluation

Chemical inactivation of cyclopropenoid fatty acids in commercial cottonseed meals was explored with three classes of compounds: anhydrous gases, organic acids and sulfhydryl compounds. Of the reagents screened, sulfur dioxide reduced the cyclopropenoid content by over 90% while free cottonseed fatty acids and thioglycollic acid reduced the cyclopropenoid fatty acid content by over 30%. Large batches of the above three selected meals, as well as a control commercial screw-pressed meal, were then incorporated at 20 wt % levels in the rations of laying hens. A negative control containing 25% soybean meal and a positive control containing a 2% refined cottonseed oil of known CPA content were also employed. During a four-week feeding period, eggs were collected during the third and fourth week and stored at 35 F for periods of 3 and 6 months. Overall egg quality and the fatty acid distribution of the yolk lipids were determined after the 3 and 6 months’ storage periods.