Toxicity profile of commercially produced indigenous banana beer

Mycotoxins, together with endotoxins, represent important classes of naturally occurring contaminants in food products, posing significant health risks to consumers. The aim of this study is to investigate the occurrence of both Fusarium mycotoxins and endotoxins in commercially produced traditional banana beer. Two brands of commercially produced traditional banana beer were collected from a local retail market in Kigali, Rwanda. Beer samples were analysed for the presence of deoxynivalenol (DON), fumonisin B₁ and zearalenone (ZEA), using an enzyme-linked immuno-sorbent assay (ELISA) method. The quantification of bacterial endotoxin using Limulus amoeboecyte lysate (LAL) assay was also conducted. The contamination levels were 20 and 6.7?µg?kg^?1 for DON; 34 and 31.3?µg?kg^?1 for FB₁; 0.66 and 2.2?µg?kg^?1 for ZEA in brands A and B of the beers, respectively. Results indicate that the levels of Fusarium toxins and bacterial endotoxin reported in this study did not pose adverse human health effects as a result of drinking/consuming banana beer. However, exposure to low/sub-threshold doses or non-toxic levels of endotoxins magnifies the toxic effect of xenobiotic agents (e.g. fungal toxins) on liver and other target organs. Considering Fusarium toxins and/or endotoxin contamination levels in other agricultural commodities intended for human consumption, health risks might be high and the condition is aggravated when beer is contaminated by mixtures of the mycotoxins, as indicated in this study.     

多元统计分析技术在市售纯生啤酒一致性研究中的应用

目的 研究不同品牌和不同工厂市售纯生啤酒特征和产品质量一致性。方法 以国内3个品牌共计9个工厂1年内生产的不同批次纯生啤酒为研究对象,采用气相色谱法测定啤酒的风味代谢产物并由国家级专业评酒委员进行样品感官评价分析,以多元统计分析方法中的主成分分析(principal component analysis,PCA)、聚类分析(cluster analysis, CA)研究不同品牌纯生啤酒一年内生产的不同批次之间的产品特质和一致性。结果 研究结果显示3个品牌之间风味代谢物差异不大,感官评价分析差异较大,B品牌一致性最差,A品牌次之,C品牌最好。B品牌出现日光臭比率为19.4%,出现均值0.18以上纸板味的比率为48.4%,缺陷量级为专业级国家评委可感知,普通消费者难以察觉,国内纯生啤酒风味评价良好。结论 多元统计分析方法可用于产品质量一致性评价,不论是生产过程中的麦汁、发酵液等半成品还是啤酒成品控制中都能够发挥一定作用,这些工具的运用可提升啤酒企业的产品质量一致性。     

Influencing the organic acid profile of beer by application of adsorbent materials

Recent publications highlight the effect of succinic acid and malic acid from alcoholic fermentation products on stomach acidity, which affects drinkability. To date, scientific information on how to reduce succinic and malic acid concentrations in beer is scarce. In order to make advances in this field, four different adsorbent materials were tested for their ability to reduce the content of these C₄‐dicarboxylic acids without harming product quality. Of these four materials, one showed a much higher absorbent capacity, and succinic and malic acids were reduced below their detection limits. Alongside a slight reduction in beer colour, a strong effect on the pH value of the treated beer was observed. Negative sensorial impacts of this increase in pH could be simply reversed by acidification of the treated beer. Further effects on foam and non‐biological stability were not observed, even though treatment reduced the total nitrogen and polyphenol content of the beer. The adsorbent material was regenerated for 10 cycles without any loss of capacity. The results indicate that, by applying this research outcome, the production of beer with a concentration of succinic and malic acids below their detection limit is possible without harming the beer's quality. This information will be helpful in the future for brewers who wish to focus on low succinic and malic acid levels as a key indicator for an ingestive drinkability effect. Copyright © 2014 The Institute of Brewing & Distilling     

Evaluation of the thermal stability and digestibility of heterologously produced banana lectin

The thermal stability of recombinant mannose-specific banana lectin (rBanLec), as well as its stability under conditions of simulated gastro-intestinal fluid (SGF), was investigated. rBanLec was heterologously produced in Escherichia coli. Molecular mass of rBanLec, assessed by ESI-TOF mass spectrometry, was 15972.2 Da. Thermodynamic parameters for rBanLec denaturation, obtained by differential scanning calorimetry (DSC), revealed a transition maximum temperature (T_m) of 60.8 °C, calorimetric enthalpy (H^cal) of 136.17 kcal/mol and van’t Hoff enthalpy (H^VH) of 50.27 kcal/mol. rBanLec was stable following an incubation for 2 h in SGF, and then for 1 h, in the simulated intestinal fluid (SIF). Intact primary structure, biological and immunological reactivity of rBanLec were all preserved following treatment under SGF and SIF conditions. In conclusion, rBanLec is a good candidate for the novel bioadhesive lectin-based drug delivery systems to the gastro-intestinal tract (GIT).     

Extraction optimization and profile analysis of oligosaccharides in banana pulp and peel

This study evaluated the effect of ethanol concentration (EC, 0–70%) and temperature (25–75 °C) on the oligosaccharides extraction from ripe banana pulp, as well as the profile of mono‐, di‐, galacto‐, fructo‐, malto‐ and xylooligosaccharides in ripe banana pulp and peel. According to response surface plots, EC of 52% (vol/vol) and 75 °C provided the maximum oligosaccharides extraction from banana pulp. High‐performance anion exchange chromatography coupled to pulsed amperometric detection showed the presence of glucose, fructose, sucrose, maltose, arabinose, 1‐kestose, xylopentaose, and xylohexaose in banana pulp and glucose, fructose, sucrose, 1‐kestose, maltotriose, xylopentaose, and xylohexaose in banana peel. Banana pulp and peel showed 6.47 and 1.42 mg/g dw of total oligosaccharides, respectively. The chromatographic analysis showed fructo‐ and xylooligosaccharides as the main banana oligosaccharides. Finally, banana can contribute to the intake of sugars and prebiotic oligosaccharides.

Practical applications

The extraction is the first step in the evaluation of the plant composition and several factors influence the recovery of the target compound. Oligosaccharides present a wide variety of applications in food science and industry and they are extensively studied in fruits metabolism. Methods with extraction conditions optimized and chromatography conditions well‐defined are very important to obtain reliable results. Furthermore, banana is one of the most consumed and processed fruits around the world and, consequently, the extraction procedure and analytical technique showed in this study can be helpful for quality control of banana and their products.     

Biogenic amines in commercially produced Yulu,a Chinese fermented fish sauce

Seven biogenic amines were determined in 35 commercially produced Yulu samples from three provinces of China by pre-column derivatisation with dansyl chloride (Dns-Cl) and high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Putrescine, cadaverine, histamine and tyramine were the major biogenic amines (more than 100 mg kg^?1), while tryptamine, spermidine and spermine were regarded as minor biogenic amines (less than 25 mg kg^?1). Twenty samples contained more than 50 mg kg^?1 histamine (the limit for histamine in seafood products as suggested by the Food and Drug Administration). Twenty-one samples contained more than 100 mg kg^?1 tyramine and 10 contained more than 1000 mg kg^?1 total biogenic amines. This study provided data on biogenic amine levels in Chinese fermented fish sauce. The results suggested that biogenic amine content should be monitored in commercially produced Yulu.     

Physicochemical characterization of sahti,an ‘ancient’ beer style indigenous to Finland

Sahti, a strong, unhopped farmhouse beer flavoured with juniper, is still actively brewed in rural areas in Finland. Presented here is the first comprehensive analysis of the physical and chemical properties of this unique beer style. Twelve sahti samples from the southwest of Finland were analysed and, while properties varied, the beers generally had high levels of alcohol (mean = 7.9% ABV) and high residual extract (mean = 9.5°P). Foam stability was negligible, as is typical for the style, and glycerol concentrations at 3.1 – 4.7 g L^?1 were higher than in reference beers (commercial lager, wheat beer and porter). These features may be attributed to the very high gravity conditions employed in brewing sahti beers. Bitterness levels were relatively low (3–13 IBU) owing to the absence or moderate use of hops. All samples contained detectable levels of the clove‐like compound 4‐vinylguaiacol owing to the use of baker's rather than brewer's yeast for brewing. Concentrations of higher alcohols and esters were high, with many individual aroma compounds being above the normal flavour thresholds. Results have highlighted the uniqueness of this style of beer in comparison to commercially available beers and have contributed to our understanding of the reasons for the particular sensorial properties of this traditional beer style. Copyright © 2015 The Institute of Brewing & Distilling     

Influence of indigenous yeasts on the fermentation and volatile profile of plum brandies

The aim of this study was to determine the influence of different yeasts isolated from fresh blue plum fruits (Aureobasidium sp.) and spontaneously fermenting plum musts (Kloeckera apiculata and Saccharomyces cerevisiae), as well as commercial wine and distillery strains, on the fermentation and chemical composition of plum brandies. Gas chromatography methods were used to detect major volatile components. The most rapid fermentation occurred in musts inoculated with S. cerevisiae. However, the highest concentration of ethanol was detected in samples after spontaneous fermentation (8.40% v/v). Plum brandies obtained after distillation contained from 66.3 (K. apiculata) up to 74.3% v/v ethanol (spontaneous fermentation). The samples after spontaneous fermentation were distinguished by a high content of acetoin, ethyl acetate and total esters, accompanied by a low level of methanol and fusel alcohols. Non-Saccharomyces yeasts were responsible for higher concentrations of esters and methanol, while S. cerevisiae strains resulted in increased levels of higher alcohols. It was also found that isolated indigenous strains of S. cerevisiae synthesized relatively low amounts of higher alcohols compared to commercial cultures. Samples obtained using the distillery strain of S. cerevisiae received the highest score (18.2) during sensory analysis and were characterized by a well-harmonised taste and aroma.     

Modification of perceived beer bitterness intensity,character and temporal profile by hop aroma extract

The effect of hop aroma on perceived bitterness intensity, character and temporal profile of beer was investigated. A hop aroma extract was added at 3 levels (0, 245, 490 mg/L) to beers at low, medium and high bitterness. Beers were evaluated for perceived bitterness intensity, harshness, roundedness and linger by a trained panel using a rank-rating technique at each bitterness level, with and without nose clips. The use of nose clips enabled the olfactory aspect to be decoupled from taste and mouthfeel aspects of bitterness perception. Results showed significant modification of perceived bitterness in beer by hop aroma depending on the inherent level of bitterness. These modifications were mainly driven by olfaction – in an example of taste-aroma interactions, as well as certain tactile sensations elicited by the hop aroma extract in the oral cavity. At low bitterness, beers with hop aroma added were perceived as more bitter, and of ‘rounded’ bitterness character relative to those without hop aroma. When judges used nose clips, this effect was completely eliminated but the sample was perceived to have a ‘harsh’ bitterness character. Conversely, at high bitterness, even when nose clips were used, judges still perceived beers containing hop aroma to be more bitter. These increases in bitterness perception with nose clips indicates the stimulating of other receptors, e.g. trigeminal receptors by hop aroma extract, which in tandem with the high bitterness, cause perceptual interactions enhancing bitterness intensity and also affecting bitterness character. Bitterness character attributes such as ‘round’ and ‘harsh’ were found to significantly depend on bitterness and aroma levels, with the second level of aroma addition (245 mg/L) giving a ‘rounded’ bitterness in low bitterness beers but ‘harsh’ bitterness in high bitterness beers. The impact of aroma on temporal bitterness was also confirmed with time-intensity measurements, and found to be mostly significant at the highest level of hop aroma addition (490 mg/L) in low bitterness beers. These findings represent a significant step forward in terms of understanding bitterness flavour perception and the wider impact of hop compounds on sensory perception.     

Flavonoid profile of Robinia honeys produced in Croatia

In this work specific pollen content, selected physicochemical parameters and flavonoid profile of 40 Croatian Robinia honeys from two production seasons were analysed. Results showed good compliance with national and international regulatory requirements, as well as with values typical for Robinia monofloral honey. All analysed samples showed same, typical flavonoid profile. Flavonoid content was different for two seasons, but rates of individual compounds remained unchanged. Higher concentrations of flavonoids were found in samples produced during dry season with high temperatures.     

Characteristics of beer produced from Korean six‐row barley with the addition of adjuncts

In this study, the effect of the addition of various amounts of adjuncts (rice, wheat, corn and potato at 10 and 20%) on the fermentation period of beer produced from Korean six‐row barley was examined. Korean six‐row barley is not suitable for brewing because of its relatively high protein/starch ratio. However, this can be offset by partially replacing the barley with adjuncts. Adjunct‐added samples were analysed and compared with the control sample made from 100% six‐row barley. All adjunct‐added samples showed changes in final beer properties (e.g. lower specific gravity, higher alcohol content, beer colour), because the initial free amino nitrogen (FAN) content was decreased and the reducing sugar content was increased. However, potato‐added samples showed a higher initial FAN level, resulting in the highest alcohol content. In addition, the colour of the potato‐added samples was darker, while the colours of the other samples were lighter. Consequently, the addition of adjuncts at a level of up to 20% had an impact on some of the quality properties of the samples in terms of fermentation period, suggesting the possibility of using Korean six‐row barley with adjuncts in brewing. Copyright © 2016 The Institute of Brewing & Distilling     

Processing methods and microbial assessment of pito (an African indigenous beer), at selected production sites in Ghana

Pito is an indigenous sorghum beer brewed on household basis with variation in product quality. The brewery processes for assuring the quality of the drink have not been clearly defined. To evaluate the brewery processes at 12 selected brewery sites in Ghana, the study adopted oral interviews/survey, observations and laboratory tests that sought to identify differences in processing methods and how they influence the quality of the drink. Pito samples were taken from selected centres at dominant producing areas: the Upper West Region (Nandom), the Northern Region (Tamale) and Ashanti Region (Kumasi). The samples were tested for aflatoxins and coliform levels, and the yeasts and moulds species present were identified. The survey results revealed that there were five similar but sequentially different processing methods currently being used to brew the drink in the selected regions. Pito samples from Kumasi had the highest mould contamination of 3.7 × 10³. The moulds identified in the beverage were Aspergillus clavatus, Mucor hiemalis, Cladosporium sphaerospemum and Cladosporium herbarum. The yeasts identified were Saccharomyces cerevisiae, Debaryomyces hansenii and Pichia anomala. Aflatoxin was absent in all of the beverage samples, although the malted grain sample from the Tech‐Junction in Kumasi showed an aflatoxin concentration of 9.58 ppb. Coliform tests were negative for all of the samples. The study, emphasizes the need for a more controlled and standard method of production to improve on the quality of the drink and to ensure the safety of its consumers. Copyright © 2016 The Institute of Brewing & Distilling     

Dominance and influence of selected Saccharomyces cerevisiae strains on the analytical profile of craft beer refermentation

This study investigated the influence of Saccharomyces cerevisiae strains inoculated at the refermentation phase on the analytical profile of craft beer. After preliminary screening of 33 S. cerevisiae strains, four were selected and used in bottle refermentation trials. To attribute the flavour profile of the refermented beers to the inoculated strains, molecular characterization was carried out using a mini‐satellite protocol of amplification with inter‐δ primers. Fingerprinting analysis of 500 isolates showed that all of the inoculated strains used in the bottle refermentation dominated the process. The main analytical characters across the bottle refermentation trials were similar, while there were distinctive and significant variations in the volatile compounds. In particular, when compared with the starter strain used as control, the bottle refermentation trials using the DBVPG 2170, DBVPG 2187 and L951 S. cerevisiae strains showed significantly higher levels of the volatile compounds that are responsible for fruity and flowery aromas (i.e. isoamyl acetate, ethyl octanoate, ethyl dodecanoate phenyl ethyl acetate, β‐phenyl ethanol). This study indicates that the proper refermentation process results in the dominance of the selected starter strain, which produces fermentation compounds that show a specific analytical profile and give the craft beer its distinctive bioflavour. Copyright © 2014 The Institute of Brewing & Distilling     

啤酒组分与泡沫稳定性的相关性研究

选取26种国内外市售啤酒为研究对象,分别利用国标法、考马斯亮蓝法和美国酿造化学家协会分析法(ASBC法)检测了啤酒泡持性、总蛋白、总糖、总多酚、粘度、pH及酒精度。结果显示:总糖、总多酚、总蛋白和黏度对啤酒泡持性的相关度较高,而pH和酒精度对泡持性影响不大。     

Detection of gluten in a pilot-scale barley-based beer produced with and without a prolyl endopeptidase enzyme

ABSTRACT

Immunochemical and mass spectrometric methods were used to examine the gluten composition of a gluten-reduced beer produced by brewing with barley malt in the presence of prolyl endopeptidase (PEP) and a final filtration treatment with diatomaceous earth and perlite. The competitive ELISA is generally considered appropriate for the analysis of hydrolysed gluten, but it is not considered a scientifically valid method for the quantification of gluten in fermented or hydrolysed foods due to the lack of an appropriate reference standard. As no single analytical method can capture the spectrum of gluten-derived products in beer, a comprehensive approach was employed to analyse the intact and hydrolysed fractions of gluten with complementary methods. The combination of PEP addition and diatomaceous earth/perlite filtration was more effective at reducing the concentration of detectable gluten than each of the treatments alone. However, gluten proteins and/or polypeptides were observed in filtered, PEP-treated beers using sandwich ELISA methods, western blot, and bottom-up mass spectrometry. In addition, mass spectrometry results showed that the number of hydrolysed gluten peptides was almost unaffected by the filtration process. Gluten peptides that contained potentially immunopathogenic sequences were identified in the filtered PEP-containing beers by MS. Variability in gluten composition was observed between three replicate pilot-scale productions, suggesting that the gluten profile in beer could differ from batch to batch. As there is uncertainty in the detection and quantification of gluten in hydrolysed and fermented foods, characterisation of hydrolysed gluten by complementary analytical methodologies is recommended.     

An improved method based on gas chromatography for determining the amino acid composition of commercially produced fish-meal

The development and refinement of a technique, based on gas chromatography, for the amino acid analysis of fish-meal are described. Emphasis is placed on streamlining the procedure to facilitate handling samples on a routine basis. Experiments are described from which data are assessed for precision. Results from these experiments confirm that the hydrolysis step contributes significantly to the reduced precision encountered in this type of analysis.     

果啤与啤酒组分差异比较研究

采用气相色谱和高效液相色谱的分析方法,分析了市售同一品牌菠萝果啤、啤酒的风味成分、有机酸、糖的组成及含量,结果表明,果啤中酯含量类物质的种类相对普通啤酒丰富,组成协调,高级醇含量低。有机酸含量果啤高于啤酒,柠檬酸积累较多。果啤中蔗糖消耗大,而果糖和葡萄糖含量有所升高。