Culinary Processing Research Articles

Effect of storage, processing and cooking on glucosinolate content of Brassica vegetables

Epidemiological studies have shown that consumption of Brassica vegetables decrease the risk of cancer. These associations are linked to dietary intake of glucosinolates and their metabolism to cancer preventive isothiocyanates. Bioavailability of glucosinolates and related isothiocyanates are influenced by storage and culinary processing of Brassica vegetables. In this work, the content of the 7 major glucosinolates in broccoli, Brussels sprouts, cauliflower and green cabbage and their stability under different storage and cooking conditions is examined. Glucosinolates and isothiocyanates were quantified by liquid chromatography with tandem mass spectrometric detection (LC–MS/MS). Isothiocyanates were detected with high sensitivity as the corresponding thiourea derivatives. Storage at ambient temperature and in a domestic refrigerator showed no significant difference and a minor loss (9–26%) of glucosinolate levels over 7 days. Vegetables shredded finely showed a marked decline of glucosinolate level with post-shredding dwell time – up to 75% over 6 h. Glucosinolate losses were detected partly as isothiocyanates. Cooking by steaming, microwaving and stir-fry did not produce significant loss of glucosinolates whereas boiling showed significant losses by leaching into cooking water. Most of the loss of the glucosinolates (∼90%) was detected in the cooking water. Increased bioavailability of dietary isothiocyanates may be achieved by avoiding boiling of vegetables.

Effect of Culinary Processes on the Content of Nitrates and Nitrites in Potatoe

The effect of potato culinary processing on the changes in the content of nitrates and nitrites was determined. The experimental material were potato tubers of Ibis, Mila and Muza varieties with elevated nitrate (175.4 - 25 0.7 mg NOkg ) and nitrite (1.7 - 4.3 mg NOkg ) content. The losses of nitrite s 3 2 -1 -1 occurring after the preliminary processing (washing, manual peeling and rinsing) were greater than nitrates and ranged from 25 to 75% and from 18 to 40%, respectively. Differences in the losses of these compounds were variety-dependent. During thermal processing of potato tubers with different methods, the losses of these compounds varied and were significantly greater for nitrites (61-98%) than for nitrates (16-62%). The greatest decrease in the content of nitrates was found for deep fried potatoes and for boiling in water. The losses of nitrates are significantly higher in peeled potato tubers subjected to thermal processing with direct contact of the product with water (p=0.05) than in steam or oil.

Radionuclide content of selected root vegetables as influenced by culinary preparation

A greenhouse study involving root vegetables (carrot, red beet, and turnips) was conducted primarily to evaluate the effect of culinary processing (light washing, scrubbing, and peeling) on the radionuclide content of the edible portions. In terms of concentration ratio of the radionuclides left in roots after peeling, the trend follows: 90 Sr> 137 Cs⪢ 234 U≅ 238 U⩾ 238 Pu . The actinide contents in the roots were apparently due to surface adherence of the contaminated soil particulates as indicated by the diminution of the contents upon brushing the surface, which were further decreased by peeling the skin. Rigorous culinary processing of roots, such as scrubbing or peeling, could substantially diminish the contents of the actinides, but not of the more mobile 90 Sr and 137 Cs .

Künstliche Makkaroni 2. Mitt. Untersuchung des Biologischen Wertes künstlicher Makkaroni

The authors determined (in vitro) the amino-acid composition and the enzymatic cleavage of protein and starch as well as (in vivo) the biological value of synthetic macaroni produced on the basis of casein, soybean protein and cotton-seed protein. The products based on casein and soybean protein have a great biological value. Cotton-seed protein has a toxic effect. The biological value of synthetic macaroni is mainly determined by the composition of the initial mixture. The processes of production and culinary processing exert no essential effects on protein content, amino-acid composition of the protein and enzymatic cleavage.