Lactic acid fermentation of brewer's spent grain hydrolysate by Lactobacillus rhamnosus with yeast extract addition and pH control

Lactic acid (LA) is a versatile chemical with a wide range of applications in food, pharmaceutical, cosmetic, textile and polymer industries. Brewer's spent grain (BSG) is the most abundant brewing by‐product. In this study BSG hydrolysates were used for LA fermentation by Lactobacillus rhamnosus ATCC 7469. The aim of this study was to evaluate the effects of pH control during fermentation, reducing sugar content and yeast extract content in BSG hydrolysate on LA fermentation parameters. The pH control greatly increased reducing sugar utilization, l ‐(+)‐LA content, yield and volumetric productivity. The highest l ‐(+)‐LA yield and volumetric productivity were achieved with the reducing sugar content of 54 g/L. Yeast extract addition significantly increased reducing sugar utilization, l ‐(+)‐LA content, L. rhamnosus cell viability, l ‐(+)‐LA yield and volumetric productivity. The highest l ‐(+)‐LA content (39.38 g/L), L. rhamnosus cell viability (9.67 log CFU/mL), l ‐(+)‐LA yield (91.29%) and volumetric productivity (1.69 g/L/h) were achieved with the reducing sugar content of 54 g/L and yeast extract content of 50 g/L. Copyright © 2017 The Institute of Brewing & Distilling     

Acid hydrolysis and fermentation of brewer's spent grain to produce xylitol

The hemicellulosic fraction of brewer's spent grain (BSG) was hydrolysed with diluted acid under different conditions of liquid/solid ratio (8–12 g g⁻¹), sulfuric acid concentration (100–140 mg g⁻¹ dry matter) and reaction time (17–37 min) in order to produce a liquor with a large amount of xylose and good fermentability to produce xylitol. Results showed that all the evaluated reaction conditions were able to hydrolyse xylan and arabinan with efficiencies higher than 85.8 and 95.7% respectively, and even under the mildest reaction condition a considerable amount (92.7%) of the hemicellulosic fraction could be extracted. The hydrolysates presented different fermentabilities when used as fermentation media for xylitol production by Candida guilliermondii yeast, owing to the differences in their composition. Based on statistical analysis, the best condition for BSG acid hydrolysis was the use of a liquid/solid ratio of 8 g g⁻¹, 100 mg H₂SO₄ g⁻¹ dry matter and a reaction time of 17 min. Under this condition a high extraction efficiency of hemicellulosic sugars (92.7%) and good fermentation results (Y_P/S = 0.70 g g⁻¹ and Q_P = 0.45 g dm⁻³ h⁻¹) were attained. Copyright © 2005 Society of Chemical Industry     

Fed‐batch l‐(+)‐lactic acid fermentation of brewer's spent grain hydrolysate

Brewer's spent grain (BSG) hydrolysates were used for l ‐(+)‐lactic acid (LA) fermentation by Lactobacillus rhamnosus ATCC 7469. The aim of this study was to evaluate fed‐batch LA fermentation of BSG hydrolysate with the addition of glucose, glucose and yeast extract, and wort during LA fermentation and its effect on fermentation parameters such as LA concentration, its volumetric productivity and yield, and L. rhamnosus cell viability. The highest LA yield, volumetric productivity and concentration of 93.3%, 2.0 g/L/h, and 116.1 g/L, respectively, were achieved with glucose and yeast extract addition during fermentation. In fed‐batch fermentation with glucose and yeast extract addition significantly higher LA concentration, yield and volumetric productivity (by 194.8; 2.2, and 20.7%, respectively) were achieved compared with batch fermentation. The results indicated that fed‐batch fermentation could be used to increase LA fermentation efficiency. Copyright © 2017 The Institute of Brewing & Distilling     

A Mini‐Review on Brewer's Spent Grain Protein: Isolation,Physicochemical Properties,Application of Protein,and Functional Properties of Hydrolysates

There is a growing demand in reusing agro‐industrial waste to enrich food proteins and develop new protein‐related products. Brewer's spent grain (BSG), the byproducts generated from the processing of beer‐brewing industry, is rich in abundant protein (26 to 30%) with good physicochemical properties and nutritional benefits. BSG is mainly composed of four proteins including hordein, gluten, globulin, and albumin. The methods for extracting protein from BSG mainly include alkali extraction, ultrasonic‐assisted extraction, and organic solvent extraction, among others. However, little researches have described the functional properties of Brewer's spent grain protein (BSGP) and how it can be improved by enzymatic modification. Additionally, BSG protein hydrolysates (BSGPHs) have good bioactivities, mainly including antioxidant, antiinflammatory, and angiotensin‐I–converting enzyme inhibitory activities, among others. Based on the above situation, this review provides a comprehensive overview about the isolation, physicochemical features, application of the BSGP. In addition, the functional properties and biological activities of BSGPHs are also emphasized. The purpose of this review is to provide an up‐to‐date summary of BSGP research, and to broaden the market potential of this emerging protein in food industry. Besides, this review provides a reference to study the use of BSGP or hydrolysates for a variety of purposes in‐depth, including pharmaceutical, food, and industrial applications.     

啤酒糟挥发油化学成分的GC-MS分析及对DPPH自由基的清除作用

采用水蒸气蒸馏法提取啤酒糟挥发油,利用气相色谱-质谱联用法（GC-MS）分析挥发油的化学成分,并以面积归一化法测定各成分的相对含量。从挥发油中共鉴定出38个化合物,占挥发油总量的91.09%,含量较高的成分有棕榈酸（48.90%）、亚油酸（26.10%）、肉豆蔻酸（3.02%）、硬脂酸（2.74%）、糠醛（1.47%）、苯乙醛（0.94%）。利用分光光度法测定啤酒糟挥发油对DPPH自由基的清除作用,其清除作用明显,清除率与样品量呈量效关系,25%挥发油IC50值为50.53μL。      

In vitro starch hydrolysis and estimated glycaemic index of bread substituted with different percentage of chempedak (Artocarpus integer) seed flour

Chempedak (Artocarpus integer) seed flour (CSF) was substituted for wheat flour at different levels (0%, 10%, 20%, 30% w/w) in bread. Assessment on the in vitro starch hydrolysis was carried out to evaluate the hydrolysis index (HI) and estimated glycaemic index (EGI) of bread substituted with different levels of CSF. Kinetics of in vitro starch hydrolysis in all bread samples (with the exception for white bread) indicated a gradual increase with respect to time intervals. Bread of 30% CSF exhibited significantly lower (p < 0.05) in vitro starch hydrolysis, as compared with the other samples. Results showed that HI value decreased significantly (p < 0.05) as the levels of CSF substitution increased. Resistant starch (RS) content in bread samples was inversely related with HI value as CSF substitution levels increased, thus lowering the EGI value.     

Evaluating the in vitro bioaccessibility of phenolics and antioxidant activity during consumption of dried fruits with nuts

Dried fruits and nuts are considered as healthy snacks and they are often consumed together in the Turkish diet. In order to investigate the effect of codigestion of dried fruits (figs, apricots, raisins) together with nuts (almonds, walnuts, hazelnuts), total phenolics (TP) and total antioxidant capacity (TAC) have been evaluated spectrophotometrically at different phases of simulated gastrointestinal (GI) digestion, using an in vitro model. TP, ABTS and CUPRAC results revealed that for all fruit–nut mixtures, the amount recovered in the dialyzed fraction was lower than the recovery of fruits or nuts alone, indicating an antagonistic effect. On the other hand, DPPH results showed that for fig–walnut, fig–hazelnut and apricot–hazelnut mixtures the quantity recovered in the dialyzed fractions were 35–107% higher than the recovery of fruits or nuts alone, representing a synergistic effect. Similarly, FRAP results also demonstrated a synergistic effect in case of fig–walnut, apricot–walnut and apricot–hazelnut mixtures (10–74% higher recovery). Current study provides valuable insights into the changes taking place during in vitro GI digestion of dried fruits and nuts.     

Bioconversion of agro‐industrial by‐products to lactic acid using Lactobacillus sakei and two Pediococcus spp. strains

The aim of this study was to evaluate the bioconversion efficiency of rich in cellulose agro‐industrial by‐products such as wheat bran (WB), spent distiller's grain with solids (DGS), brewer's spent grain (BSG) and lupin (Lupinus angustifolius L.) wholemeal fraction (LF) to lactic acid (LA) using acid tolerant lactic acid bacteria (LAB) strains Lactobacillus sakei KTU05‐06, Pediococcus acidilactici KTU05‐7 and P. pentosaceus KTU05‐9. Carbohydrase preparation Depol^? 692L was used for the hydrolysis of non‐starch polysaccharides. Analysed raw materials were suitable substrates for LAB propagation and L‐lactic acid production. The lowest pH (3.6) was found in LF medium after 48 h fermentation with P. acidilactici and P. pentosaceus strains. The lowest pH (3.86) was measured in WB fermented with L. sakei, and in DGS and BSG (pH 3.8 and 3.9 respectively) fermented with P. acidilactici. The highest endoxylanase activity was excreted by the P. acidilactici and P. pentosaceus (84 and 69 XU g^?1 respectively), and the highest α‐amylase activity was of L. sakei (255.6 AU g^?1) after 24 h incubation in WB medium. The L‐lactic acid concentration of 86.11 g kg^?1 was reached after the bioconversion of hydrolysed WB in combination with 48 h fermentation by P. pentosaceus KTU05‐9 strain. LA contents between 222 and 282 mg kg^?1 was produced from lupin processing residues via fermentation using P. acidilactici and P. pentosaceus KTU05‐9 strains. The major challenge within the presented study is the viability of tested LAB in cereal waste media and effective LA production at a low pH (3.6–3.8).     

Characterisation of protein‐rich isolates and antioxidative phenolic extracts from pale and black brewers' spent grain

Protein‐enriched isolates and co‐product fractions were obtained from sheared, pale and black brewers' spent grain (BSG) using sequential aqueous and alkaline (110 mm NaOH) extraction, followed by isoelectric precipitation at pH 3.8. A recovery of 59% of the original pale BSG protein and 15% of the black BSG protein was obtained for the final isolates. Gel permeation HPLC (GP‐HPLC) revealed that 59% of the extracted pale BSG protein and only 6% of black BSG protein had a molecular mass >10 kDa. Glutamine/glutamate and proline were the most abundant amino acids present in both isolates. Analysis of four co‐product fractions obtained during fractionation from both pale and black BSG revealed the presence of phenolics, with higher concentrations in the black BSG extracts. These fractions possessed antioxidant and free radical scavenging activity when tested using the ferric reducing ability of plasma (0.16 ± 0.01 to 4.33 ± 0.11 mg Trolox equivalents g^?1 BSG dry weight) and diphenylpicrylhydrazyl (12.85 ± 1.16% to 59.50 ± 3.47% DPPH?_sc) assays, respectively. The protein‐enriched isolates and the phenolic‐rich extracts may find use as value‐added ingredients for incorporation into conventional and functional foods.     

Compaction and relaxation characteristics of single compacts produced from distiller’s spent grain

Compaction and relaxation characteristics of densified distiller’s spent grain compacts produced at different levels of compressive pressure (60.3–135.7 MPa), initial moisture content (15%, 20% and 25% wb) and soluble content (15% and 30%) were analyzed during the study. The compaction levels used in this study caused up to a 4% wb reduction in the moisture of compacts in comparison to their initial moisture. The density of compacts was analyzed to determine the compaction characteristics of distiller’s spent grain using Jones model. Analysis of the Jones model showed that there was a significant (P = 0.004) decrease in compressibility with an increase in soluble content from 0% to 30%. The distiller’s spent grain compacts were subjected to relaxation tests and the relaxation data obtained were normalized and analyzed to determine the asymptotic modulus (E_A) of the compacts. The asymptotic modulus was used as a measure of rigidity of the compacts. Distiller’s spent grain compact produced with a compressive force of 135.7 MPa and initial moisture of 25% wb possessed the highest E_A value.     

Modification of enzymatic and non-enzymatic in vitro oxidative defence system by bioaccessible phytonutrients of selected spices

The bioaccessibility and bioactivity of spice polyphenols using the in vitro model simulating gastro-intestinal conditions and intestinal absorption has been investigated.     

Antioxidant capacity and anthocyanin profile of sour cherry (Prunus cerasus L.) juice

The antioxidant capacities, total polyphenolic content and monomeric anthocyanin content of eleven types of sour cherry juice obtained from different varieties of sour cherries were investigated. Antioxidant capacity, total polyphenolic content and monomeric anthocyanin contents of the juices were within the ranges 20.0–37.9 mmol/L, 1510–2550 and 350.0–633.5 mg/L, respectively. The main anthocyanin compound in sour cherry juice was cyanidin-3-glucosylrutinoside at concentrations between 140.3 and 320.9 mg/L. Cyanidin-3-glucosylrutinoside was followed by cyanidin-3-rutinoside within a concentration range of 25.5–85.5 mg/L. Cyanidin-3-sophoroside and cyanidin-3-glucoside contents were relatively low (2.6–21.5 and 2.0–9.9 mg/L). Anthocyanin capacity and total polyphenol content were fairly well correlated (r = 0.742, p < 0.01), whereas the correlation between antioxidant capacity and monomeric anthocyanin content was insignificant (r = 0.423, p > 0.05). The correlation between antioxidant capacity – cya-3-glucosylrutinoside (r = 0.606, p < 0.01) and antioxidant capacity – cya-3-rutinoside (r = 0.628, p < 0.01) was significant.     

The hydroxycinnamic acid content of barley and brewers’ spent grain (BSG) and the potential to incorporate phenolic extracts of BSG as antioxidants into fruit beverages

The hydroxycinnamic acid (HA) content of starting barley for brewers’ spent grains (BSG), whole BSG and phenolic extracts from BSG was measured using high performance liquid chromatography (HPLC) and correlated with antioxidant potential. The effect of BSG phenolic extracts on antioxidant activity of fruit beverages was also assessed (using the total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays). The concentration of HA present in barley extract and BSG was in the order of ferulic acid (FA), p-coumaric acid (p-CA) derivatives, FA derivatives, p-CA, caffeic acid (CA) and CA derivatives. Results suggested that brewing and roasting decreased the HA content. Antioxidant activity was significantly (P < 0.05) correlated with caffeic acid (R² = 0.8309) and total HA (R² = 0.3942) concentrations. Addition of extracts to fruit beverages resulted in a significant (P < 0.05) increase in antioxidant activity of cranberry juice, measured by the FRAP assay. In vitro digestion significantly (P < 0.05) reduced TPC, DPPH and FRAP activity of the fruit beverages.     

Antioxidant capacity,total phenolic and ascorbate content as a function of the genetic diversity of leek (Allium ampeloprasum var. porrum)

Extracts of the white shaft and green leaves of 30 leek cultivars were investigated for their antioxidant properties, total phenolic (TP) and l-ascorbic acid (AA) content. The measured antioxidant properties included free radical scavenging activities against peroxyl (ORAC) and 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH) and their Fe³⁺ reducing capacity (FRAP). The results from this study suggest that the green leek leaves generally have significantly stronger antioxidant properties than the white shaft. Correlation analysis between the TP and the AA content and the antioxidant activity showed that phenolics and ascorbic acid contribute significantly to the antioxidant activity of leek. The three antioxidant activity assays were all correlated for the extracts of the white shaft of the 30 leek cultivars. Principal component analysis (PCA) elucidated the influence of part and type of cultivar on the antioxidant capacity, TP, and l-ascorbic acid content, whilst the breeding strategy and seed company had no influence.     

Effect of in vitro digestion upon the antioxidant capacity of aqueous extracts of Agrimonia eupatoria, Rubus idaeus, Salvia sp. and Satureja montana

An in vitro digestion/Caco-2 cell culture model was used to assess the stability and bioavailability of phenolic compounds in aqueous extracts of four herbal infusions, traditionally used as functional drinks in Portugal. Alterations in antioxidant power were monitored by ABTS⁺, whereas the profile of phenolic compounds was ascertained by HPLC-DAD. The bioavailability of rutin - an important flavonoid present in such extracts, and thus a representative of those compounds, was assessed across Caco-2 cells via LC-MS/MS. Our results indicate that several antioxidant compounds are not affected by the (simulated) digestive process, whereas others undergo decreases in their activity throughout said process; a few have their antioxidant capacity hampered under stomach-like conditions. It was also found that rutin can be transported across the Caco-2 cell barrier.     

Free and bound total phenolic concentrations,antioxidant capacities,and profiles of proanthocyanidins and anthocyanins in whole grain rice (Oryza sativa L.) of different bran colours

To study the polyphenols in whole grain rice varying in bran colour, the total phenolics, flavonoids and antioxidant capacities of the solvent-extractable (Free) and cell-wall bound (Bound) fractions and the profiles of proanthocyanidins and anthocyanins were determined. Red and purple bran rices had significantly higher total (sum of Free- and Bound-) phenolic (PC) and flavonoid (FC) concentrations and antioxidant capacities than light-coloured bran rice or other cereals (P < 0.05), due to their higher concentrations of proanthocyanidins and anthocyanins, respectively. The concentrations of the Bound-PC and FC accounted for approximately half of the total PC and FC in the light-coloured bran rice, but were lower than those in purple and red bran rice (P < 0.05). High correlations were found between the concentrations of total phenolics and the three antioxidant capacity assays except for those in the bound fraction when related to iron chelating capacity. The concentrations of proanthocyanidins in red bran rice was 1.27 mg/g and its composition was 6.5%, 33.5%, 30.6% and 29.4% of 1–3, 4–6, 7–10 mers, and polymer (>10 mers), respectively. Cyanidin-3-glucoside was the predominant anthocyanin and peonidin-3-glucoside was the second highest; the profiles varied between purple bran cultivars. Whole grain rice differing in bran colour contained unique polyphenol subgroups, which have been proposed to positively impact human health.     

Antioxidant capacity of four polyphenol-rich Amazonian plant extracts: A correlation study using chemical and biological in vitro assays

Many plants used in Amazonian folk medicine present a high antioxidant activity. In this study, the antioxidant activities of four largely used plants, namely Byrsonima crassifolia, Davilla kunthii, Davilla rugosa and Inga edulis, were evaluated, using methanolic extracts of their leaves, fruits and bark and several different in vitro tests, based either on the capacity to scavenge free radicals (ORAC, TRAP) or on the ability to protect biological structures (LDLs, erythrocytes). The total phenolics (TP), flavanoids (TFA) and flavonols (TFO) were also measured. Almost all extracts performed well in all assays of antioxidative capacity, with best activities found in leaves (compared to fruits and bark). Most antioxidative performance indicators (ORAC, TRAP, LDL protection) correlated well with the TP and TFA content of the extracts. Conversely, correlation was lower between TFO and these indicators, reflecting a lower involvement of these compounds in antioxidant processes. Erythrocyte protection against oxidant-triggered haemolysis showed no correlation with any of the phenolic content indicators, suggesting that most of these compounds have a low ability to protect lipid targets in the erythrocyte membrane. On the other hand, protection of erythrocytes against haemolysis correlated positively with LDL protection. The extract of I. edulis leaves contained average amounts of polyphenols but ranked first in the majority of the tests, indicating the occurrence of particularly efficient compounds with very important antioxidant properties, which could be used for medicinal and other applications.