Raw Malt Research Articles

Preliminary Research on the Analytical and Volatile Profiles of Beers Produced with Raw Malt and Roasted Specialty Malts

Preliminary research was conducted on the analytical and flavor profiles of beers brewed (small-scale) with roasted specialty malts and raw malts as adjuncts. Beers were characterized by physico-chemical, sensory, and GC-MS analysis. From the beers produced, 79 volatile compounds were identified, and these were grouped into different categories. Alcohols and esters were found to be the most prevalent volatile compounds in the beers. Principal component analysis, as well as cluster analysis, was applied in order to investigate the similarities and distinctions between the various types of adjuncts and no adjunct beers. The volatile chemicals present in the beers showed that the nature and quantity of these compounds would have an effect on the flavor and quality of the beers. Beers prepared with the roasted wheat malt addition were characterized by the highest number of volatile compounds. Moreover, the beers with roasted wheat malt addition were characterized by higher bitterness (higher than the control beer), high antioxidant activity (equal to the control beer), and a high tannin content (but less than the control beer). Beers were evaluated by a sensory panel that concluded that the adjunct beers had a preferred flavor to the beers without adjunct addition. The highest-rated beer in the appearance, flavor, mouthfeel, and overall acceptability criteria was the adjunct beer with roasted wheat malt incorporated. This preliminary experimentation will help guide where future research is needed and where scale-up experiments with trained taste panels should focus.

Effects of Wheat Malt-Derived Endo-Β-1, 4-Xylanase Supplementation on The Quality of Wheat Beer

Endo-β-1, 4-xylanase (EC 3.2.1.8) is a key enzyme in the degradation of Arabinoxylan (AX). AX and its degradation products are the key substances that affect the viscosity, turbidity, filtration speed, alcohol, foam performance, and health care function of wheat beer. A wheat malt-derived endo-β-1, 4-xylanase was isolated and purified by our group in the previous stage. The aim of this study was to investigate the effects of the wheat malt-derived endo-β-1, 4-xylanase addition on the quality and composition of AX in hopped wort and wheat beer. The results showed that the content and the average degree of polymerization (avDP) of water-soluble arabinoxylan (WEAX) in hopped wort and wheat beer decreased with the increase of the addition level of the wheat malt-derived endo-β-1,4-xylanase. When the addition of wheat malt-derived endo-β-1,4-xylanase was 2.5 times of the activity of endo-β-1,4-xylanase in raw malt, the degradation rate of WEAX in hopped wort was the maximum (33.71%), and the avDP of WEAX was the minimum (29.74) at the addition level of the endo-β-1,4-xylanase was 2 times. The viscosity and turbidity of hopped wort and wheat beer decreased continuously with the increase of the addition level of the endo-β-1,4-xylanase, while the foam stability of wheat beer increased continuously. Wheat malt-derived endo-β-1,4-xylanase could decrease the content of 1320-6200 Da polysaccharide in wheat beer, but increase the content of<1320 Da polysaccharide.

UPLC-Q-TOF-MS/MS analysis on the chemical composition of malts under different germination cycles and prepared with different processing methods

Objective: To investigate changes in the chemical composition of malts under different germination cycles and prepared with different processing methods, thus providing a reference for the clinical application of malt in disease treatment. Methods: Nine malt samples were analyzed by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS), and the MS fragmentation pathway of 4 compounds (including hordenine, gramine, N-methyltyramine and catechin) were also analyzed. Results: By database comparison and literature search, we detected 31 compounds in raw barley and 33 compounds in both raw malt and roasted malt. Nonetheless, the most of these 33 compounds were detected higher contents in raw malt than in roasted malt. Besides, we detected 15 compounds in brown malt. At Day1 of germination, 31 compounds were detected in malt, without two alkaloids (representative: hordenine). At Day2–5, 33 compounds were detected, with different contents as shown by the peak area comparison; hordenine had a gradually increasing abundance; and nearly one third of the chemical components in barley increased gradually, one third decreased gradually, and one third tended to be stable. Conclusion: Malts under different germination cycles and prepared with different processing methods have varying active ingredients, and especially brown malt exhibits a serious loss of compounds. The tight association between the chemical composition and clinical application of malt offers a basis to the clinically scientific and reasonable selection of Chinese medicinal materials for treatment purposes.

A combination of chemical and physical pretreatments in the saccharification of malt bagasse: the effects of ultrasonication in diluted acid medium

Malt bagasse is a lignocellulosic byproduct of the brewery industry and is rich in fibers and proteins. It is produced in abundance and can be reused as a substrate to obtain fermentable sugars. However, to obtain an efficient enzymatic saccharification, pretreatments must be used. The objective of this study was to evaluate the combination of ultrasonication in diluted acid medium as a pretreatment of lignocellulosic biomass to obtain fermentable sugars and residual solid fractions with increased susceptibility to enzymatic hydrolysis. The residual solid fractions were characterized according to their composition, morphology, crystallinity, and thermal stability. Malt bagasse was submitted to different pH values (3–5), ultrasonication times (10–60 min), and biomass contents (6–10%, w/v). The effect of the time was the most important variable; more time resulted in higher sugar release and greater changes in the residual solid fraction recovered after pretreatment. In general, the residual solid fractions of pretreated samples demonstrated a higher crystallinity index and thermal stability than raw malt bagasse. The sample processed at pH 5 for 60 min with a biomass concentration of 8% resulted in the highest cellulose content and lowest lignin content. In this study, the use of acid hydrolysis combined with ultrasonication decreased the time required for the maximum hydrolysis efficiency when compared with literature data, and it was which is an interesting result considering an economical point of view; however, future studies should be conducted with the aim of reducing the process times and energy costs.

Reuse of regenerated immunoaffinity column for excellent clean-up and low-cost detection of trace aflatoxins in malt

The high price of the immunoaffinity column (IAC) has limited its broad application in the cleanup of analytes from complex matrices. This study aimed to reduce practical cost by regenerating IACs for reuse in cleaning up and purifying aflatoxin (AF) B1, B2, G1 and G2 from medicinal and edible malt samples, followed by high-performance liquid chromatography coupled with photochemical derivatization and fluorescence detection (HPLC-PCD-FLD). The IACs were prepared in advance by coupling anti-AFs specific antibodies (Abs) on a solid phase carrier. After each use, the IACs were washed immediately with phosphate-buffered saline (PBS) and pure water, respectively, and then were filled with PBS as the preservation solvent for storage at 4 °C overnight to recover the binding activity of the immobilized Abs for the regeneration and reuse in the next day until the recovery rate was lower than 70%. Results showed that the developed HPLC-PCD-FLD method displayed good linearity in wide concentration range with the limit of detection (LOD) and quantification (LOQ) of 0.3125–0.5 ng/mL and 1–1.5 ng/mL for the four aflatoxins, as well as excellent accuracy and precision with relative standard deviations (RSDs) <5.5% and <7.0%, respectively. The IACs could be used at least nine times for AFB2, AFG1, and AFG2 when intruding the recommended method in Huaan Magnech Bio-Tech IAC instructions for raw malt sample preparation. And the corresponding consumption could be reduced to one-ninth of the original cost. Due to the high toxicity and incidence of AFB1, the IACs were suggested for reuse twice regarding this aflatoxin in malt with half of the original cost. The reuse of the regenerated IACs for excellent clean-up and low-cost detection of trace AFs in complex matrices is economical, green and environment-friendly, expecting widespread application of more mycotoxins in sophisticated food and traditional Chinese medicine matrices with low cost.

Regeneration and Reuse of Immunoaffinity Column for Highly Efficient Clean-Up and Economic Detection of Ochratoxin A in Malt and Ginger.

Immunoaffinity columns (IACs) are most popularly used for mycotoxin clean-up in complex matrices prior to chromatographic analysis. But, their high cost has limited their wide application and the regeneration of IACs for multiple instances of reuse is important. This study aimed to investigate the feasibility of regeneration and reuse of IACs for purification of ochratoxin A (OTA) in spiked raw malt and dried ginger samples followed by high performance liquid chromatography-fluorescence detection. After each use, the IACs were filled with phosphate buffer saline (PBS) as the preservation solution and stored at 8 °C overnight for regeneration and reuse until the recovery rate was <70%. The results showed that matrix type, preparation procedure, and pH value of sample extraction exhibited major effects on the reuse of IACs for OTA clean-up. While, after modifying the sample preparation procedure using water as the diluent and the solution at a pH of 7 to 8, the IACs could be used eight and three times for the spiked raw malt and dried ginger samples with OTA after regeneration. Regarding the traditional procedure recommended in Chinese Pharmacopoeia (2015 edition), the IACs could be used for three and two times for the spiked raw malt and dried ginger samples with OTA, respectively. Therefore, the corresponding experimental cost could be reduced to one-eighth and one-third of the original cost. This is the first study on the regeneration and reuse of IACs for OTA clean-up in complex Chinese herbal medicines, providing a green and economical tool for a large number of samples analysis with low cost.

Immunochemical determination of gluten in malts and beers

The gluten content in different varieties of barley and malts, and in different types of beers, was determined by a ‘sandwich’ enzyme immunoassay (RIDASCREEN® Gliadin kit). The gluten levels in barley wheat, rye and spelt malts ranged 18.8–45.0, 44.0–68.0, 41.6 and 21.2 g kg–1, respectively. When various types of beer were compared, the gluten concentration increased as follows: alcohol-free beer (<3.0), lager beers (<3.0–8.7 mg l–1), stouts (9.0–15.2 mg l–1) and wheat beers (10.6–41.2 mg l–1). When 10 Czech lager beers were analysed, using both sandwich and competitive ELISA, the results showed that the latter method provided values several times higher than the former. Gluten balance was carried out during the brewing process, starting from the raw materials and terminating at the final beer. Gluten levels decreased due to precipitation during the mashing process, primary and secondary fermentation and, lastly, as a result of adsorption during beer stabilization. The gluten content in beer is, thus, approximately three orders of magnitude lower than in the raw malt.

Biomass and carotenoid pigment production by patagonian native yeasts

New yeast isolates from unexplored Patagonian habitats were studied for the production of biomass and carotenoids as the first step towards the selection of hyper-producing strains and the design of a process optimization approach. Patagonian yeast isolates considered as potential biomass and carotenoid sources were studied using ammonium sulphate and urea as nitrogen sources in semi-synthetic medium (MMS), and agro-industrial byproducts (cane molasses, corn syrup, raw malt extract) as carbon sources. Maximum pigment production (300 μg g−1) was achieved by Rhodotorula mucilaginosa CRUB 0195 and by novel species Cryptococcus sp. CRUB 1046. β-carotene, torulene and torularhodin were the major carotenoids found.