Black rice addition prompted the beer quality by the extrusion as pretreatment

Abstract

Flavor compounds, including total polyphenols, amino acids, and protein, in beer with extruded black rice as adjunct were detected and analyzed. Beer brewing technique has been intensively investigated in the past century. The chase of beer quality, including the color, flavor, foam, nutrition, and functionality, attracted considerable attention. Hence, headspace solid‐phase microextraction in combination with a gas chromatography coupled to mass spectrometry (HS‐SPME‐GC–MS) was used to analyze flavor compounds qualitatively and quantitatively. A total of one organic acid, one aromatic, ten alcohols and 23 esters were present in extruded black rice adjunct beer. Protein components and molecular weight were analyzed, and the results were consistent with those of traditional beer in terms of content of foam‐stabilizing protein. The contents of essential amino acid which is an important nutritive index were higher than those in traditional rice adjunct beer, especially valine (70.9 mg/L) and threonine (42.8 mg/L). The representative ingredients of extruded black rice adjunct beer were polyphenols, nerolidol, geraniol, and geranylgeraniol which affected the functionality and antioxidant ability.

Impact of germination on the chemical profile of HomChaiya rice wort and beer

“…The rice beer's amino acid contents vary widely with the process and the rice species. Zhang et al (2019) 42 observed proline, alanine, glutamic acid, and valine as the dominant amino acids in the rice beer, and this finding contrasts with the present study. Amino acid contents are the crucial sources of nutrition to yeast.…”

Brewing with Starchy Adjuncts: Its Influence on the Sensory and Nutritional Properties of Beer

“…More recently, research has investigated how the incorporation of extruded adjuncts influences beer brewing. In terms of organoleptic characteristics, a higher number and concentration of aroma compounds have been detected in beers using extruded grains as adjuncts than in those brewed with unextruded adjuncts [15,100,101]. A study published in 2018 shows a higher content of aroma compounds in extruded corn starch beer than in cooked corn starch beer [101].…”

“…In another study by Zhang et al in 2019, using extruded black rice, novel compounds (nerolidol, geraniol and geranylgeraniol) were detected that were not present in unextruded black rice beers. Therefore, the use of extruded grains can be interesting from a sensory point of view for brewing [15].…”

“…For all these factors, the use of adjuncts in brewing is a growing market in the United States of America and Europe [14] and they are currently included in the brewing of 85-90% of beers produced globally [15].…”

“…Adjuncts are generally considered to be alternative sources to barley malt that contribute fermentable sugars to the brewing wort. This definition includes non-malted solid raw materials, liquid adjuncts and malted cereals other than barley [15,16]. Trace elements, such as iron, copper and zinc, are relevant due to their role as cofactors in metabolic and biosynthetic processes, such as beer fermentation [17].…”