Effects of heat‐moisture and alkali treatment on the enzymatic hydrolysis of porous sago ( Metroxylon sagu ) starch

Abstract

Pretreatment(s) of heat-moisture treatment (HMT) and alkali treatment was tested for the enzymatic hydrolysis of sago (Metroxylon sagu) starch. HMT was undergone by autoclaving the sago starch at 120°C for 60 min. While sodium hydroxide pellets (0.60% [w/w starch dry basis (d.b.)] to 50 g of sago starch) were applied as the alkali treatment. Dual pretreatments were also evaluated. The dextrose equivalent values of porous starch with alkali pretreatment (31%), HMT (37%), and dual pretreatments (42%) were significantly higher than those of non-pretreated porous sago starch (21%). Greater porosity of pretreated starch granules (0.91–5.19 µm) was also obtained. The thermal properties (gelatinization temperature) of porous starch with pretreatments were improved compared to the non-pretreated porous sago starch. In addition, the pretreatment(s) also improved the oil adsorption capacity of the porous starch. Dual pretreatments were an efficient way to facilitate enzymatic hydrolysis in preparing porous sago starch. Practical applications Porous starch is in high demand as a natural carrier for food applications such as flavor retention, food structure improvement, and extension of food shelf life. The porosity of the starch provides higher surface area and better immobilization to food ingredients, especially as a functional food. The abundance and lower cost of sago starch added the preference. Hence, the main purpose of the study is to produce highly porous sago starch granules with enhanced surface area to fulfill the processing requirement of food industries. Thus, the effect of pretreatment(s) on sago starch using heat-moisture and alkali treatments prior to enzymatic hydrolysis was evaluated. Both heat-moisture and alkali pretreatment(s) enhanced the enzymatic hydrolysis of sago starch and formed the intended porous structure. Porous sago starch has better absorption capacity and efficient oil adsorption. Besides, the thermal properties of pretreated sago starch were improved compared to the non-pretreated porous sago starch. Hence, the pretreated sago starch is the potential to be an excellent adsorbent. Overall, the outcome shows that the objective is positively achieved via the dual of the pretreatment(s).