Hydrolysis of Native and Heat-Treated Starches at Sub-Gelatinization Temperature Using Granular Starch Hydrolyzing Enzyme

Abstract

The effect of heat treatment below the gelatinization temperature on the susceptibility of corn, mung bean, sago, and potato starches towards granular starch hydrolysis (35°C) was investigated. Starches were hydrolyzed in granular state and after heat treatment (50°C for 30 min) by using granular starch hydrolyzing enzyme for 24 h. Hydrolyzed heat-treated starches showed a significant increase in the percentage of dextrose equivalent compared to native starches, respectively, with corn 53% to 56%, mung bean 36% to 47%, sago 15% to 26%, and potato 12% to 15%. Scanning electron microscopy micrographs showed the presence of more porous granules and surface erosion in heat-treated starch compared to native starch. X-ray analysis showed no changes but with sharper peaks for all the starches, suggested that hydrolysis occurred on the amorphous region. The amylose content and swelling power of heat-treated starches was markedly altered after hydrolysis. Evidently, this enzyme was able to hydrolyze granular starches and heat treatment before hydrolysis significantly increased the degree of hydrolysis.

Simultaneous cold hydrolysis and fermentation of fresh sweet potato

“…As discussed in the Introduction section, the hydrolysis of granular starch usually demands greater amount of enzymes than the hydrolysis of gelatinized starch. Regarding works of Uthumporn et al [24], Shariffa et al [25] and Li et al, who also worked with Stargen™ 002, this volume of enzymes is in agreement to the ones reported by them. However, these studies used media with greater concentrations of solids than the one achieved in this study: between 250 g L À1 and 300 g L À1 of dried mass.…”

“…The production of glucose when hydrolysis is carried out without any pretreatment is around half of the production in the case with pretreatment. The same observation was also reported by others authors [24,25]. The improvement in the experiments with pretreatment can be ascribed to the partial gelatinization of starch due the fact that the pretreatment temperature (62 C) is inside the range of gelatinization temperature (Section 3.1).…”

“…For minimizing the cited problems, a preheating step, at subgelatinization temperature, is sometimes suggested by the producer of enzymes [23]. This pretreatment aims to make the granular starch more susceptible to enzyme action and its influence has already been discussed in the literature [24,25].…”

Changes in physicochemical properties and in vitro starch digestion of native and extruded maize flours subjected to branching enzyme and maltogenic α-amylase treatment

“…Additionally, the formation of prebiotic isomaltooligosacharides has been also reported [8,12]. It is important to consider that native starch is only partially accessible for the enzyme catalysis, being necessary to promote previously the damage or breakage of the starch granules [13]. Therefore, whereas those previous treatments were carried out on starches, research on flours subjected to extrusion process is scarce.…”

Purification and characterization of a novel cold adapted fungal glucoamylase

“…Amylases hydrolyze α-glucosidic bonds in starch and according to their catalytic mechanism they are classified into three main groups: (i) α-amylase, which disrupts α-1,4-glycosidic linkages; (ii) β-amylase, which catalyzes the hydrolysis of the second α-1,4 glycosidic bonds from the non-reducing end of starch; and (iii) glucoamylase (an α-glucosidase), which acts on both, α-1,4 and α-1,6 glycosidic bonds from the non-reducing end of the starch molecule [10–13]. Amylases are used in several industrial processes, including the production of high-fructose corn syrup, as additives in detergent formulations, in wool treatment and to obtain fermentable sugars from starch-rich wastes that are used as a substrate for biofuels production [13, 14]. The efficient microbial production of biofuels from raw starch wastes requires the complete degradation of starch, which is currently accomplished by the addition of α-amylase and glucoamylase during the fermentative process to release glucose as the primary end product [15, 16].…”