Nano-encapsulation of naringinase produced by Trichoderma longibrachiatum ATCC18648 on thermally stable biopolymers for citrus juice debittering

Abstract

Characteristics of naringinase nano-encapsulated forms on different carrier materials (chitosan and alginate polymers) were investigated in this study. Screening of twelve fungal isolates for naringinase production indicated that Trichoderma longibrachiatum was the most promising. Grapefruit rind was used as a substrate containing naringin for naringinase production. TEM micrographs showed that chitosan nano-capsules were applied for the production of morphologically homogeneous enzymatic nano-particles with high enzyme encapsulation efficiency, small asymmetric sizes (from 15.09 to 27.07 nm with the mean of 21.8 nm) and rough surfaces compared to nano-encapsulated naringinase in alginate which showed nano-particle size (from 33.37 to 51.01 nm with the mean of 43.03 nm). It was revealed that the highest naringinase activity was found in case of chitosan nano-capsule naringinase compared to alginate nano-capsule one. Thermogram analysis (TGA) showed that the free enzyme loses about 92% of its weight at approximately 110°C, while the nano-encapsulated ones show more stability at higher temperatures. Conclusively, the nano-capsulation process improves the kinetics and operational stability so could be useful as a debittering agent for various thermal processing applications in citrus juices industries which makes the fruit juice more acceptable and cost-effective to the consumer.