Effect of blanching conditions and solar drying on selected nutritional, anti-nutritional and bioactive components of formulated avocado seed powder

Abstract

Avocado (Persea americana Mill) seeds are mainly considered as waste by-products of avocado fruit processing in many countries, including Tanzania despite their potential health and economic benefits. The present work investigated the effect of hot water blanching and solar drying treatments on nutritional, bioactive, and cyanogenic glycosides of avocado seed samples in an attempt to develop quality avocado seed powders (ASPs) by using solar drying technology. Results showed that total ash, crude protein, crude fiber, total phenolic, proanthocyanidins, and cyanogenic glycosides contents showed a significant reduction in avocado seed powders with respect to increased blanching temperature and time. On the other hand, crude fat and total carotenoids contents, showed a decline with respect to increased temperature only. Blanching treatment at 85 °C for 10 minutes retained a significant amount of total ash (86.9%), crude fat (100%), crude protein (78.8%), crude fiber (91.6%), total carotenoids (43.6%) and total phenol contents (47.0%) in developed avocado seed powder. Cyanogenic glycosides were highly reduced at 95 °C for 20 minutes (81.1%) than at 85 °C for 10 minutes (58.5%). However, the level of cyanogenic glycosides in all avocado seed powders are far below the lethal dose (36 mg/100 g) of hydrocyanic acid. The significant high losses of nutrients and phytochemicals was observed at a blanching treatment of 95 °C for 20 minutes. This could be due to prolonged leaching of soluble compounds to hot water and degradation of heat-sensitive bioactive compounds. The aforementioned results revealed that, different temperatures and times during hot water blanching significantly influence the quality of formulated avocado seed powder. Therefore, hot water blanching treatment at 85 °C for 10 minutes and solar drying technology could be employed to produce a nutrient-rich and palatable avocado seed powder that can find its use in normal food consumption and food processing industries, particularly in low income settings. Key words: Avocado seed, avocado seed powder, solar drying, hot water blanching, utilization