Abstract

Fructan fatty acid esters are amphiphilic compounds with potential applications in the food industry due to their surface-active properties on the air/water interface. In this work, the regioselective synthesis of fatty acid esters of short-chain inulin-type fructooligosaccharides (FOS) was carried out in a two-step process comprising sequential enzymatic reactions of transfructosylation and acylation. In the first step, Schedonorus arundinaceus sucrose:sucrose 1-fructosyltransferase (1-SST, EC 2.4.1.99) converted sucrose (600 g/L) into the trisaccharide 1-kestose and the tetrasaccharide nystose in a ratio 9:1 with their sum accounting for 53% (w/w) of total carbohydrates. In the second step, the FOS mixture was transesterified with vinyl laurate in 2-methyl-2-butanol by immobilized Candida antarctica lipase B (CALB) (EC.3.1.1.3). NMR analysis of the synthesized monolaurate FOS esters revealed a regioselective acylation of the 6-OH of the terminal fructosyl moiety of both 1-kestose and nystose. The hydrophilic-lipophilic balance (HLB) values of 6’’-O-lauroyl-1-kestose and 6’’’-O-lauroylnystose were 14.7 and 15.7, respectively; which suggests their use as oil in water (O/W) emulsifiers. The main compound 6’’-O-lauroyl-1-kestose with critical micelle concentration (CMC) of 0.6 mM and surface tension of 45.8 mN/m proved to be a more efficient surfactant than 6’’’-O-lauroylnystose (CMC 5.38 mM) and surface tension 36.26 mN/m). We report a regioselective method for the synthesis of lauryl-FOS using the abundant and renewable resource sucrose as the starting substrate.

摘要

果聚糖脂肪酸酯是两亲化合物，由于其在空气/水界面上的表面活性特性，在食品工业中具有潜在应用。在这项工作中，短链菊粉型低聚果糖 (FOS) 脂肪酸酯的区域选择性合成分两步进行，包括转果糖基化和酰化的连续酶促反应。在第一步中，Schedonorus arundinaceus蔗糖:蔗糖 1-果糖基转移酶 (1-SST, EC 2.4.1.99) 将蔗糖 (600 g/L) 转化为 9:1 的三糖 1-酮糖和四糖 nystose，它们的总和占总碳水化合物的 53% (w/w)。在第二步中，FOS 混合物与月桂酸乙烯酯在 2-甲基-2-丁醇中通过固定化南极念珠菌脂肪酶 B (CALB) (EC.3.1.1.3)。合成的单月桂酸酯 FOS 酯的 NMR 分析揭示了 1-酮糖和 nystose 的末端果糖基部分的 6-OH 的区域选择性酰化。6''- O -lauroyl-1-kestose 和 6'''- O -lauroylnystose的亲水亲油平衡 (HLB) 值分别为 14.7 和 15.7；这表明它们可用作水包油 (O/W) 乳化剂。关键胶束浓度 (CMC) 为 0.6 mM 和表面张力为 45.8 mN/m的主要化合物 6''- O -lauroyl-1-kestose 被证明是比 6'''- O更有效的表面活性剂-月桂酰蔗糖 (CMC 5.38 mM) 和表面张力 36.26 mN/m)。我们报告了一种使用丰富且可再生的资源蔗糖作为起始底物合成月桂基-FOS 的区域选择性方法。