Preservation of Chayote (Sechium edule L) using different drying methods

Abstract

Chayote (Sechium edule L) has a high moisture content range from (87-95%) resulting in a short-shelf life and high postharvest losses. Reduction of moisture content post-harvest can prolong its shelf life. This study aimed at prolonging the shelf life of chayote by using different drying methods. Diced chayote was subjected to drying using convection air drying (60C for 0-27 h), solar drying (35.3-55.6℃for 0-120 h), and osmotic dehydration using (10% sugar or 10% salt for 3h followed by convection drying at 60C for 0-27 h). Drying curves were plotted to determine the time taken to reach 20% moisture content. At 20% moisture content, the nutritional properties of chayote were determined (ash, dietary fiber, total sugars and starch, vitamin C and zinc). Rehydration, textural and sensory properties of dried chayote were also determined. The dried chayote was stored for three months while determining microbial counts (total plate count (TPC), coliforms, Staphylococcus and yeasts and moulds) and assessing sensory attributes of the product monthly. The time to dry to 20% moisture varied significantly (p < 0.05) from 9 h (air dried and osmo-dried chayote in sugar), 12h for osmo-dried chayote in salt to 98h (solar dried). The findings indicated that ash, total sugar, starch and fiber increased significantly (p ˂ 0.05) from fresh sample as follows 5.2 - 28.3 g/100g, (in OD salt), 5.8 - 18.5 g/100g, (in OD sugar), 18.4 - 21.3 g/100g, (in OD sugar), 49.1 - 52.9 g/100g, (in OD sugar) respectively after drying. Vitamin C decreased from 232.5 - 38.4 mg/100g, (air dried) while zinc decreased from 1442.9 - 29.5 mg/100g, (air dried). Rehydration ratio varied from 2.0 ± 0.26 (OD salt after 30 min) to 2.9 ± 0.05 (air-dried after 20 min). Osmotically dehydrated samples were softer than air dried samples after rehydration and cooking. All samples were acceptable although OD- salt and fresh sample were significantly (p ˂ 0.05) more acceptable than the OD- sugar and air dried samples. The microbial quality and sensory acceptability of the dried chayote improved with time during the three months of storage. The study found that osmotic dehydration contributed to the preservation of the nutritional, textural and sensory properties of dried chayote with salt achieving better preservation than sugar. Drying also increased the shelf life of chayote from days to three months with high microbial quality and sensory acceptability. Therefore, farmers and processors should adopt drying with osmotic dehydration as a pre-treatment as a means of reducing postharvest losses in chayote. Further studies can determine the effect of packaging and storage temperature on the physicochemical, nutritional, and sensory properties of dried chayote.