Osmo-predried fluted pumpkin (Telfairia occidentalis) leaf and its nutri-economic evaluation

Abstract

Purpose Leafy vegetables are known to be highly perishable because of high moisture content, which had resulted in applications of different preservative methods. However, these methods were not without certain limitations during storage. Osmotic pre-dehydration had been proved to be a better alternative because of high retention and improvement in nutritional qualities and stability during storage. This study aims to investigate the osmotic pre-dehydration of fluted pumpkin (Telfairia occidentalis) leaves. Design/methodology/approach Fluted pumpkin (T. occidentalis) leaves were pre-dried using sucrose, corn syrup and sodium chloride solutions as osmotic agents, while unosmo-predried leaves were used as the control. Both osmo-predehydrated and unosmo-predried leaves were dried in a hot air oven, whereas the effect of the osmotic agents on the nutritional qualities was investigated using standard protocols. Findings There were significant differences (p-values ranged from 0.001 to 0.030) in the proximate compositions of samples. Osmo-predried leaves recorded higher mineral contents in Ca, Cu, Fe, K, Mg, Mn and Na. Osmotic pre-dehydration by NaCl had a significant effect (p = 0.02) on ascorbic acid. The amino acid profile of the oven-dried leaves (unosmo-predried) showed that histidine and cysteine recorded high amino acid scores of 120.42% and 135%, respectively. Threonine (43.73%) recorded the highest essential amino acid score (without histidine). The economic evaluation indicated the percentage cost index difference of leaves treated with NaCl as 2.08%, sucrose (11.19%) and corn syrup (16.43%). Originality/value The high proportion of beneficial elements such as calcium, magnesium, phosphorus, potassium and appreciable chemical compositions of the osmo-predried leaves compared to unpre-dried leaves proved osmotic pre-dehydration as a value-added technique for preservation of leafy vegetables. The best osmotic agent was sodium chloride. This process could be applied on a small scale for the development of self-entrepreneurs and home-scale industries.