Physicochemical and Anti-nutrients Analysis of Pasteurised and Unpasteurised Underutilised Sweet Potato Haulm Juice Powder

Abstract

Under the cash-crop category, sweet potato (Ipomoea Batatas L.) has the second widest plantation area (3, 623 hectares) in Malaysia, after sweet corn. The sweet potato crop had been grown for its edible tubers, leaving behind the top parts of the plants, which led to abundant agricultural waste, around 10 tonnes per hectare. Early studies showed that haulm (unused tops of the plants consisting of stem, stalk, and leaf) from sweet potato plants are a potential source of nutritional contents, including bioactive materials and antioxidants. Suppose the haulms or other fruit and vegetable waste (FVW) are utilised as these nutrient sources benefit Malaysia in terms of consumption and economy, promoting agricultural sustainability. In this study, the sweet potato haulm undergoes slow-juicing, heat-treatment, and freeze-drying. This research focused on elucidating the physicochemical and anti-nutrients analysis of pasteurised and unpasteurised sweet potato haulm juice powder (SPHJP) (water activity, colour analysis, water solubility index, oxalic acid, and phytic acid) as a potentially edible product. Results significantly showed that pasteurised SPHJP had lower water activity (0.34 aw), lower anti-nutrients concentration (oxalic acid and phytic acid), and a higher water solubility index than the unpasteurised SPHJP (p<0.05). It is proven that heat treatment is crucial when utilizing green waste material, as it can reduce the availability of anti-nutrients and increase its potential as a replacement for other green vegetables. Further study must be conducted to convert this underutilised agricultural product into biofertilisers, bioplastics, biofuels, or nutraceutical products.