Effects of drying and heat pretreatments on the fatty acid compositions of spinach

초록

Spinach, one of widely used leafy vegetables providing essential fatty acids, is used in a fresh state and processed forms. Although processing can expand the utilization of spinach, quality deterioration could occur. To reduce this deterioration, pretreatment such as blanching before drying is usually done. However, there could be also changes in its components during pretreatment. This research was performed to study the effects of drying and heat treatment prior to drying on the fatty acid compositions in lipid classes in spinach by separation of total lipid(TL) into neutral lipid(NL), glycolipid(GL) and phospholipid(PL), followed by gas chromatography. Pretreatment included blanching for 2 minutes(BL2), blanching for 20 minutes(BL20) and steaming for 5 minutes(ST5). Vaccum drying and FIR drying were used after heat pretretment. In vacuum-dried spinach, linolenic acid in TL decreased with increase in linoleic and oleic acid. However, FIR drying resulted in decrease in linolenic and linoleic acid by the pretreatment. NL showed little difference in fatty acid compositions among heat pretreated samples even though there was a tendency of decreasing linolenic acid. GL showed the highest difference among TL, NL, GL and PL by the heat pretreatment. GL of BL20 was the most oxidation susceptible. PL showed the least difference among differently heat treated spinach samples. Especially little effect of heat pretreatment on fatty acid compositions in PL of vacuum-dried spinach was observed. In conclusion, vacuum drying showed less effect on the fatty acid composition than FIR drying, and steaming(ST5) was the least affective in vacuum-dried spinach lipid.