Microencapsulation of α-amylase in beeswax and its application in gluten-free bread as an anti-staling agent

Abstract

In this work, α-amylase was encapsulated into beeswax and the effects of independent variables including beeswax content (1–3 g), enzyme concentration (0.78–1.82 mg/ml), Tween 20 level (0.5–1%) (w/v), and stirring rate (800–1200 rpm) on the encapsulation efficiency of the encapsulated enzyme were optimized using response surface methodology (RSM). Beeswax content and enzyme concentration were significant parameters (p < 0.05). Besides, the optimum conditions for the maximum encapsulation efficiency (40%) were 1 g beeswax, 1.82 mg/ml α-amylase, 1% (w/v) Tween 20 and 800 rpm stirring rate. Scanning electron microscopy (SEM) photos confirmed the size of encapsulated α-amylase between 3.98 and 69.53 μm. The catalytic efficiency of encapsulated enzyme (EE) was about 2 fold lower than that of free enzyme (FE). EE also showed higher thermal and storage stability than FE. The application of EE in gluten-free batter and bread was studied using rheometer, texture analyzer, and sensorial evaluation, implying that EE remained relatively stable in acidic medium of batter and EE-containing breads showed a significantly lower hardness and higher sensorial quality than FE-loaded ones during 5 days of storage period. These results suggested that this enzymatic treatment is efficient in retarding gluten-free bread staling and can be used in bakery industry.