Tempe is a fermented soybean product originating from Indonesia. The efects of manufacturing conditions, i. e., soaking, boiling, fermentation and home cooking by stewing or firing, and the effect of pure cultures of microorganisms commonly occurring in tempe towards their production of toxicants like biogenic amines and ethyl carbamate were investigated. The level of biogenic amines in soaked soybeans was rather low (total < 28Oppm), and not signijicantly affected by boiling, but considerably increased by fermentation.The finctional fingus Rhizopus oligosporus mainly produced tyramine and some putrescine (total biogenic amines approximately 1800 ppm). With added inoculation of Klebsiella pneumoniae and Trichosporon beigelii, the total amount of biogenic amines increased slightly (2000, resp. 2100 ppm) with a shift towards cadavenne. With added Lactobacillus plantarum, a reduction of tyramine levels resulted in a considerably lower total level of biogenic amines (approx. lo00 ppm). Storage at 5C did not affect the level of biogenic amines, whereas at 25C, increased levels ofputrescine were observed. Home cooking by stewing had little effect, butfrying in oil resulted in significant decreases of both 'corresponding author Safety 13 (1993) 293-303. A11 Rights Reserved. Yopyright I993 by Food & Nutrition Press, Inc., Trumbull, Connecticut. 293 294 M. NOUT, M. RUIKES, H. BOUWMEESTER and P. BELJAARS putrescine and tyramine. Preventive measures to keep biogenic amines at low levels in tempe are recommended. They include inoculation with selected lactic acid bacteria which cannot produce but can degrade biogenic amines, andfrying instead of stewing of tempe. Ethyl carbamate levels were negligible (< 11 ppb) in all treatments; this was attributed to the absence of significant concentrations of ethanol in the product. Journal of Food

A liquid chromatographic (LC) method was developed for determination of tocopherols and tocotrienols in foods. Tocopherols and tocotrienols were released after saponification of test portions for 40 min at 80°C, followed by extraction with hexane-ethyl acetate. After evaporation of the organic solvents, the extract was injected into the LC system. Separation of individual tocopherols and tocotrienols was satisfactory. Some interferences were encountered from tocomoneols, tocodienols, 2-tert-butyl-4-hydroxyanisole (BHA), 2,6-di-tert-butyl-4-methylphenol, (BHT), and plastochromanol-8. The response of the LC system was linear over a range of 0-10 μg/mL for tocopherols and tocotrienols. The detection limit for these compounds was 0.1 μg/mL. Repeatabilty relative standard deviation values for tocopherols and tocotrienols in margarine, infant formula, and broccoli (concentration range, 0.11-22 mg/100 g) varied from 1.3 to 6.4%. Recoveries ranged from 91 to 105%.

An interlaboratory study of the liquid chromatographic (LC) determination of histamine in fish, sauerkraut, and wine was conducted. Diminuted and homogenized samples were suspended in water followed by clarification of extracts with perchloric acid, filtration, and dilution with water. After LC separation on a reversed-phase C18 column with phosphate buffer (pH 3.0)-acetonitrile (875 + 125, v/v) as mobile phase, histamine was measured fluorometrically (excitation, 340 nm; emission, 455 nm) in samples and standards after postcolumn derivatization with ophthaldialdehyde (OPA). Fourteen samples (including 6 blind duplicates and 1 split level) containing histamine at about 10- 400 mg/kg or mg/L were analyzed singly according to the proposed procedure by 11 laboratories. Results from one participant were excluded from statistical analysis. For all samples analyzed, repeatability relative standard deviations varied from 2.1 to 5.6%, and reproducibility relative standard deviations ranged from 2.2 to 7.1%. Average recoveries of histamine for this concentration range varied from 94 to 100%

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An interlaboratory study of the gel permeation chro-matographic (GPC) determination of polymerized triglycerides (PTG) in frying fats and oils was conducted by the Project Group on Collaborative Studies (PCS) of the Inspectorate for Health Protection, Food Inspection Service, The Netherlands. Thirteen laboratories participated in this study, which was focused on thermally abused oil and fat samples containing dimerized and polymerized triglycerides at levels just below and far above the Dutch regulatory limit of 16% (m/m). Samples were dissolved in tetrahydrofuran (THF) and analyzed on a GPC system, using THF as the mobile phase. Refractive index (Rl) detection was used to determine PTG. Six heat-processed fat samples containing from 14 to 28% (m/m) PTG at 3 different levels (3 pairs of split level samples) were single analyzed according to the proposed procedure. Data analysis was performed according to the International Union of Pure and Applied Chemistry/International Organization for Standardization/AOAC protocols for statistics. The results of 2 collaborators were identified as outliers at the 20% (m/m) PTG level by applying the paired Grubbs test at the 1% level of significance. The repeatability relative standard deviation (RSDr) values ranged from 0.48 to 2.25%, whereas the reproducibility relative standard deviation (RSDr) values ranged from 1.34 to 4.57%.