Development of vegetables powder based nutrients dense food product

Abstract

Worldwide, millions of tons vegetables are produced but majority of this surplus produce goes to waste prior finding place on the food table. Postharvest losses of vegetables in Pakistan are highest i.e. upto 45%. Failure to convert high value and underutilized vegetables to value added foods of economic significance does not only escalate risks of poor access of vegetables in consumer market but also contribute to the burden of food insecurity and nutritional inadequacies among economically weaker population groups. Nexus to the problem stated, this study was planned to investigate functional, nutritional, toxicological, rheological properties of microwave heat treated, blanched, acid and base treated vegetables powders i.e., spinach, cabbage and potato powders. The study also probed the proximate composition, mineral profiling, toxicological, textural and organoleptic features of spinach, cabbage and potato powders supplemented unleavened flatbread (chapatis) at @ 2.5 – 10%. Comparative assessment of functional features of raw & processed forms of spinach, cabbage and potato powders anticipated the raw versions to elucidate significantly (p<0.05) higher values of water solubility index, water absorption index and swelling power. Proximate analysis of raw spinach powder revealed significantly (p<0.05) higher amounts of fibers (8%), ash (3%) and protein (19%) contents than processed spinach, while, highest fibers (10%), ash (3.8%) and protein (19%) contents were displayed by microwave heat treated, acid soaked and alkali soaked spinach powders, respectively. Raw cabbage powder elucidated significantly (p<0.05) higher ash, fiber & proteins i.e., 10, 25 and 12% respectively. While, processed versions of cabbage powder recorded highest ash (10.8%), fibers (24.1%) and proteins (12.1%) in acid soaked, microwaved & blanched powders. Raw potato powder revealed higher nutritional contents than processed i.e., ash (3.1%), fibers (5.7%) and proteins (10%) in microwave heat treated potato powders. Raw spinach, cabbage and potato powders exhibited higher minerals (Na, Ca, K, Fe and Zn) than processed vegetables powders. Microwave treated spinach powder reduced the alkaloids, oxalates, tannins and phytates contents by 86, 87, 85 and 89%, respectively. Among processed cabbage powders revealed maximum decline in alkaloids, oxalates, tannins and phytates by 77, 85, 84 and 86%, respectively on exposure to microwave heat treatment. Heavy metals (i.e., As, Cd, Ni and Pb) in all vegetables samples were observed under safe limits. Microwave heat treatment resulted in highest decline of imidacloprid, cypermethrin, bifenthrin, chlorpyrifos, and deltamethrin in spinach by 86, 74, 84, 80 and 77%, respectively. Microwave heat treated cabbage and potato powders showed 60 – 90% decline in imidacloprid, cypermethrin, bifenthrin, chlorpyrifos, and deltamethrin contents than raw. Spinach and cabbage powders rheological studies revealed decrease in water absorption by 4 – 9%, dough stability by 3 – 12%, while increase in peak height by 14 – 27%. Raw and processed spinach, cabbage and potato powders’ based chapatis anticipated significant (p<0.05) improvement in fibers (1.7 – 4.6%), ash (0.4 – 1.4%) and proteins (8.1 – 11%). Mineral contents of raw and processed spinach, cabbage and potato powders supplemented chapatis @ ~ 10% were significantly (p<0.05) improved than control. Processed spinach powder based unleavened flat breads were recorded to contain significantly (p<0.05) lower amounts of alkaloids (6.1 mg/100g), oxalates (12.2 mg/100g), tannins (4.1 mg/100g) and phytates (3.1 mg/100g) than raw spinach powder supplemented chapatis at ~ 10% supplementation. Similarly, all processed versions of cabbage and potato powder supplemented chapatis elucidated significantly (p<0.05) lower concentrations of alkaloids (5.4 and 3.1 mg/100g), oxalates (0.6 and 0.6 mg/100g), tannins (23 and 1.5 mg/100g) and phytates (1.1 and 0.8 mg/100g), respectively. Pesticides residues were found in safer limits in the processed chapatis prepared @ 10% supplementation with spinach, cabbage and potato powders. Spinach powder supplementation (~10%) resulted in significant (p<0.05) increase in L * values (70 – 60) and b * values (19 – 24), hardness (0.2 – 0.9 N), chewiness (0.6 – 1.4 mm) and gumminess (0.6 – 1.4 N, mm), while, cabbage powder based chapatis showed increase in a * values (2.1 – 4.6), hardness (0.3 – 0.6 N), chewiness (0.4 – 0.9 mm) and gumminess (0.4 – 1 N, mm). Raw and processed potato powder based chapatis resulted in increased a * values (1.9 – 2.6), b * values (11 – 14) and, hardness (3.2 – 8.2 N), while significant decrease in chewiness (1.3 – 0.7 mm), gumminess (3.1 – 1.6 N, mm). Puffing of raw and processed spinach, cabbage and potato powders supplemented chapatis significantly (p<0.05) decreased from 6.4 –3.3 cm. The results for sensory evaluation refers the supplementation of spinach powder in wheat flour based unleavened flat breads (i.e., chapatis) @ 7.5%, while, the cabbage and potato powders @ 5% as viable approach to develop value added baked goods. Conclusively, the findings suggests the use of household microwave heating treatment at 1.1 kW for 2 minutes as commendable approach to reduce intrinsic and extrinsic toxicants. Better functional features of dehydrated vegetables are suggestive of their application as cost effective ingredients for improving the nutritional, thickening & functional properties of savory foods such as curries, soups & gravies.