EFFECT OF BLANCHING AND DRYING PROCESS ON CAROTENOIDS COMPOSITION OF UNDERUTILIZED ETHIOPIAN (COCCINIA GRANDIS L. VOIGT) AND INDIAN (TRIGONELLA FOENUM-GRAECUM L.) GREEN LEAFY VEGETABLES

Processing effect on Coccinia grandis (ivy gourd) and Trigonella foenum-graecum (fenugreek) carotenoids was studied. This paper presents findings on the effect of blanching (boiling water, saline water and steam) and drying (lyophilizer, sun, shade and dryer) on retention of carotenoids. Carotenoids were extracted, identified and quantified by high performance liquid chromatography technique. Xanthophylls (neoxanthin, violaxanthin, lutein, zeaxanthin) and beta-carotene were detected in both vegetables, while on the contrary, alpha-carotene was identified only in ivy gourd. Ivy gourd had a higher total of xanthophylls (104 mg/100 g) and hydrocarbon carotenoids (35 mg/100 g) than fenugreek with 86 mg/100 g and 31 mg/100 g, respectively (all dry weight basis). Results reveal that blanching methods did not affect carotenoids level as compared with raw. Except lyophilization, drying methods significantly reduced most carotenoids, sun drying being highly detrimental. It is recommended to use ivy gourd as source of carotenoids for health benefits. Among the processing methods tested, boiling water blanching is most preferable. PRACTICAL APPLICATIONS The results of the present study contain original data on the effect of processing on carotenoids, which are highly beneficial for health. Since there was no systematic study previously conducted on the effect of processing methods on the level of the different carotenoids in green leafy vegetables, the present study findings fill this knowledge gap, an important area in the field of food science and technology. The findings are not only useful in the processing of vegetables at household or higher scale level, but also open a new area of study in the field of food chemistry, mainly, contributing factors that make some carotenoids relatively tolerant to processing than the other carotenoids, mechanisms that affect reduction of carotenoids as well as extent of carotenoids absorption in humans following the different processing methods.