Simultaneous saccharification and fermentation of broken rice: an enzymatic extrusion liquefaction pretreatment for Chinese rice wine production

Abstract

Broken rice, pretreated by enzymatic extrusion liquefaction, was used to produce Chinese rice wine by simultaneous saccharification and fermentation (SSF) process in this study. The study compared the novel process and traditional process for Chinese rice wine fermentation utilizing broken rice and head rice, respectively. With the optimum extrusion parameters (barrel temperature, 98 °C; moisture content, 42% and amylase concentration, 1‰), 18% (v/v at 20 °C) alcoholic degree, 37.66% fermentation recovery and 93.63% fermentation efficiency were achieved, indicating enzymatic extrusion-processed rice wine from broken rice exhibited much higher fermentation rate and efficiency than traditional-processed rice wine from head rice during SSF. The starch molecule distribution data indicated that the alcoholic degree was related to the oligosaccharides' formation during enzymatic extrusion. Sum of amino acid (AA) in the extrusion-processed wine was 53.7% higher than that in the traditional one. These results suggest that the enzymatic extrusion pretreatment for broken rice is a feasible and alternative process in the fermentation of Chinese rice wine.

Metagenomic sequencing reveals the relationship between microbiota composition and quality of Chinese Rice Wine

“…A. Oryzae has strong secretion of amylases including alpha-amylase, which will certainly accelerate the degradation of grains and provide more nutrients for microbes in fermentation. Li, H. et al 27 reported an improvement of rice wine fermentation using grinded grains, suggesting the importance of quick grain degradation in the course of rice wine fermentation. The results here revealed that different microbial makeup greatly influenced the fermentation process.…”

Influence of Enzymatic Extrusion Liquefaction Pretreatment for Chinese Rice Wine on the Volatiles Generated from Extruded Rice

“…This may be due to the synergy of extrusion shear and enzymatic hydrolysis, which improved the digestion of protein in sticky rice flour, and because of the reduced Maillard reaction in the enzymatic exturdates, which would benefit the reserve of AAs as Maillard reaction substrates. Furthermore, the content of AAs in enzymatic extrusion‐processed rice wine was approximately 2‐fold higher than conventional extrusion‐processed wine (Lu and others ; Li and others ). A possible reason may be the advantage of AA reservation in enzymatic extruded rice.…”

“…There are 3 explanations offered: (1) the formation of Maillard‐style volatiles can be inhibited by controlled extrusion conditions at relatively mild levels as described in this study; (2) the release of total volatiles may be enhanced by mild extrusion conditions, especially those lipid‐derived volatiles; (3) the promotion of the reactions between the degradation products of starch, protein, and lipid may be due to the modified reaction environment by increased SME and reduced enzyme activity, which would increase the relative amounts of total volatiles in mildly enzymatic extruded rice. Zhengyu Jin and others (Li and others ) had already demonstrated that the hydrolysis rate of amylopectin increased with thermostable α‐amylase added during enzymatic extrusion, and rice starch was mainly degraded into maltose under low‐temperature operating conditions. Moreover, an optimal product temperature level (94.84 to 96.65 °C) detected for the selected thermostable enzyme at 90 °C also merited attention.…”

“…Many high‐starchy cereals that are processed by extrusion pretreatment instead of traditional steam cooking—an intensive water, energy‐consuming, and low‐throughput process for modern industry—are used as fermenting materials of Chinese rice wine production in the last 2 decades (Xu and others ). By comparison, the content of amino acids (AAs) in the enzymatic extrusion‐processed rice wine was approximately 1.5 times higher than that in traditional Chinese rice wine (Li and others ), but reduced to only three‐quarter times when no enzymatic hydrolysis was performed in extrusion (Lu and others ). The AAs are not only the primary nutrients in Chinese rice wine but the precursors of the Maillard reaction products as well.…”

“…Enzymatic extrusion liquefaction, or enzymatic hydrolysis in extrusion cooking, of cereals is used widely in the fields of oil and protein extraction, starch saccharification, and fermentation (Govindasamy and others ; Lee and others , ; De Mesa‐Stonestreet and others ). The extruder runs as a bioreactor to liquefy starch or protein in feedstock with heat‐stable enzymes addition at mild extrusion conditions of low temperature (70 to 110 °C) and high moisture (30% to 65%) generally (Govindasamy and others ; Tomas and others ; Li and others ). The advantages of such a composite processing unit over conventional extrusion cooking or other multistep heat‐treated methods are economic and efficient in terms of reduction in energy and the usage of raw materials.…”