Valorization of Avocado Seed Starch Waste into Glucose Syrup using Amylases from Aspergillus niger

The rising demand for alternative sweeteners and the need for sustainable agro-industrial waste management imply the importance of developing new sources for glucose syrup production. This study was carried out to explore the enzymatic conversion of starch derived from avocado (Persea americana Mill.) seed waste into glucose syrup as a valorization strategy for underutilized byproducts. Amylases were produced by Aspergillus niger through solid-state fermentation (SSF) using avocado seed waste as the substrate. The crude enzyme was partially purified by ammonium sulfate precipitation at 40–60% saturation, followed by dialysis. Enzyme activity, determined via the dinitrosalicylic acid (DNS) method, reached 0.633 U mL-1. The partially purified amylase was then applied to hydrolyze avocado seed starch (10% w/v) at enzyme concentrations of 1.0%, 1.5%, and 2.0% (v/v). Glucose syrup quality was evaluated based on reducing sugar content, viscosity, moisture, ash content, and organoleptic properties. The highest syrup quality was achieved at 1.0% enzyme addition, producing syrup with 40% reducing sugars, 309 cP viscosity, 16% moisture, 0.5% ash, and a dextrose equivalent of 51%, meeting the Indonesian National Standard (SNI 2978:2021). These findings demonstrate the feasibility of utilizing A. niger-derived amylase for converting avocado seed starch into glucose syrup, offering an environmentally friendly alternative to conventional starch sources while promoting the valorization of agricultural waste.