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Research Project: Defining, Measuring, and Mitigating Attributes that Adversely Impact the Quality and Marketability of Foods

Location: Healthy Processed Foods Research

Title: Preparation and characterization of gellan gum microspheres containing a cold-adapted beta-galactosidase from Rahnella sp. R3

item FAN, YUTING - Jiangnan University
item YI, JIANG - Shenzhen University
item HUA, XIAO - Jiangnan University
item Zhang, Yuzhu
item YANG, RUIJIN - Jiangnan University

Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2017
Publication Date: 1/11/2017
Citation: Fan, Y., Yi, J., Hua, X., Zhang, Y., Yang, R. 2017. Preparation and characterization of gellan gum microspheres containing a cold-adapted beta-galactosidase from Rahnella sp. R3. Carbohydrate Polymers. 162:10-15.

Interpretive Summary: Lactase is the enzyme that breaks down the disaccharide sugar lactose in milk. In most of the world’s population, the production level of lactase are high in infants and down-regulated after weaning. Low level of lactase expression in the small intestine causes the common symptoms of adult-type lactose intolerance. Although populations in some areas of the world were first thought to have high rates of lactase persistence, a large percentage of the world population are affected with lactose intolerance. This has a negative impact on the marketing and utilization of milk product. Cold-adapted beta-galactosidase from Rahnella sp.R3 is active at four degrees and can be used in the manufacturing of lactose-reduced milk and other dairy products. It can also increase the sweetness of milk product as it convert lactose to glucose and galactose. But it is unstable at moderate temperatures. This manuscript reports the stabilization of the enzyme by incorporating it with gellan gum hydrogels, making the application of this enzyme possible for dairy food processing where enzyme activity at low temperatures and stability to mechanical shear are necessary.

Technical Abstract: R-ß-Gal is a cold-adapted ß-galactosidase that is able to hydrolyze lactose and has the potential to produce low-lactose or lactose-free dairy products at low temperatures (4°C). Cold-adapted enzymes unfold at moderate temperatures due to the lower intramolecular stabilizing interactions necessary for flexibility at low temperatures. To increase stability and usage-performance, R-ß-Gal was encapsulated in gellan gum by injecting an aqueous solution into two different hardening solutions (10 mM CaCl2 or 10 mM MgCl2). Enzyme characteristics of both free and encapsulated R-ß-Gal were carried out, and the different effects of two cations were investigated. R-ß-Gal showed better thermal and pH stability after encapsulation. Ca2+ gels had higher encapsulation efficiency (71.4%) than Mg2+ (66.7%) gels, and Ca2+ formed larger inner and surface pores. R-ß-Gal was released from the Ca2+ hydrogel beads more rapidly than the Mg2+ hydrogels during storage in aqueous solution due to the larger inner/surface pores of the matrix.