The Occurrence of Beer Spoilage Lactic Acid Bacteria in Craft Beer Production

Beer is one of the world's most ancient and widely consumed fermented alcoholic beverages produced with water, malted cereal grains (generally barley and wheat), hops, and yeast. Beer is considered an unfavorable substrate of growth for many microorganisms, however, there are a limited number of bacteria and yeasts, which are capable of growth and may spoil beer especially if it is not pasteurized or sterile‐filtered as craft beer. The aim of this research study was to track beer spoilage lactic acid bacteria (LAB) inside a brewery and during the craft beer production process. To that end, indoor air and work surface samples, collected in the brewery under study, together with commercial active dry yeasts, exhausted yeasts, yeast pellet (obtained after mature beer centrifugation), and spoiled beers were analyzed through culture‐dependent methods and PCR‐DGGE in order to identify the contaminant LAB species and the source of contamination. Lactobacillus brevis was detected in a spoiled beer and in a commercial active dry yeast. Other LAB species and bacteria ascribed to Staphylococcus sp., Enterobaceriaceae, and Acetobacter sp. were found in the brewery. In conclusion, the PCR‐DGGE technique coupled with the culture‐dependent method was found to be a useful tool for identifying the beer spoilage bacteria and the source of contamination. The analyses carried out on raw materials, by‐products, final products, and the brewery were useful for implementing a sanitization plan to be adopted in the production plant.     

Influence of pH and temperature on the growth of and toxin production by neurotoxigenic strains of Clostridium butyricum type E

Strains of Clostridium butyricum that produce botulinal toxin type E have been implicated in outbreaks of foodborne botulism in China, India, and Italy, yet the conditions that are favorable for the growth and toxinogenesis of these strains remain to be established. We attempted to determine the temperatures and pH levels that are most conducive to the growth of and toxin production by the six strains of neurotoxigenic C. butyricum that have been implicated in outbreaks of infective and foodborne botulism in Italy. The strains were cultured for 180 days on Trypticase-peptone-glucose-yeast extract broth at various pHs (4.6, 4.8, 5.0, 5.2, 5.4, 5.6, and 5.8) at 30 degrees C and at various temperatures (10, 12, and 15 degrees C) at pH 7.0. Growth was determined by checking for turbidity; toxin production was determined by the mouse bioassay. We also inoculated two foods: mascarpone cheese incubated at 25 and 15 degrees C and pesto sauce incubated at 25 degrees C. The lowest pH at which growth and toxin production occurred was 4.8 at 43 and 44 days of incubation, respectively. The lowest temperature at which growth and toxin production occurred was 12 degrees C, with growth and toxin production first being observed after 15 days. For both foods, toxin production was observed after 5 days at 25 degrees C. Since the strains did not show particularly psychrotrophic behavior, 4 degrees C can be considered a sufficiently low temperature for the inhibition of growth. However, the observation of toxin production in foods at room temperature and at abused refrigeration temperatures demands that these strains be considered a new risk for the food industry.     

Chemical composition,sensory and cooking quality evaluation of durum wheat spaghetti enriched with pea flour

The goal of the study was to obtain spaghetti enriched with pea flour with sensory properties close to conventional pasta. To this aim, the study has been organised in two subsequent trials. In the first, the pea flour amount added to the spaghetti was continuously increased until the overall sensory quality reached its threshold value (pea flour concentration = 15%). In fact, the spaghetti samples supplemented with 15% pea flour (15%S‐P) showed less elasticity, unpleasant colour and higher firmness compared to the control sample (CTRL). The second step was aimed to improve the overall sensory quality of the 15%S‐P spaghetti by means of guar gum (GUAR). The sample with GUAR (15%S‐P/GUAR) showed a pleasant colour, odour and taste. Furthermore, the 15%S‐P/GUAR sample recorded a low starch digestibility value (i.e. 54) and a higher soluble fibre content with respect to the 15%S‐P sample.     

Strain-specific polyketide synthase genes of Aspergillus niger

In silico comparison of 34 putative pks genes in Aspergillus niger strain CBS 513.88 versus A. niger strain ATCC 1015 genome revealed significant nucleotide identity (>95% covering a minimum of 99% of the gene sequence) for 31 of these genes (approximately 91%). A. niger CBS 513.88 harbors three putative pks genes (An01g01130, An11g05940, and An15g07920), for which nucleotide identity was not found in A. niger ATCC 1015. To compare the results of the in silico analysis with the in vivo situation, experimental data were obtained for a large number of A. niger strains obtained from different substrates and geographical regions. Three putative pks genes that were found to be variable between the two A. niger strains using bioinformatics tools were in fact strain-specific genes based on experimental data. The PCR amplification signals for the An01g01130, An11g05940, and An15g07920 pks genes were detected in only 97%, 71%, and 26% of the strains, respectively. Southern blot analyses confirmed the PCR data. Because one of the strain-specific pks genes (An15g07920) is located in a putative ochratoxin cluster, we focused our investigation on that region. We assessed the ochratoxin production capability of the 119 A. niger strains and found a positive association between the presence of this pks gene and the capability of the respective strain to produce ochratoxin.     

Apparent chemical composition of nine commercial or semi-commercial whey protein concentrates, isolates and fractions

Summary Analytical results are given for whey powders prepared on a commercial or semi-commercial scale by three companies. Altogether, five preparations enriched in β-lactoglobulin, four whey protein isolates and a fraction enriched in α-lactalbumin were analyzed for protein composition, including %β-lactoglobulin, α-lactalbumin, bovine serum albumin, casein (glyco) macropeptide and the main triglycerides. Protein composition was determined by high pressure gel permeation and reversed phase liquid chromatography and by capillary zone electrophoresis. The extent of modification of the native β-lactoglobulin structure was also measured through the degree of lactosylation and the fraction of accessible free sulphydryl groups. One significant finding was that the calculated recovery of protein following quantitation of the chromatogram or electropherogram was seldom above 90% and occasionally below 60% of that loaded onto the column or capillary, raising doubts as to the reliability of the analytical results. Extrapolation by linear regression to 100% recovery allowed estimates to be made of the true β-lactoglobulin composition of the samples. The nine samples could be placed into three distinct groups with estimated true β-lactoglobulin weight % of 70.9 ± 1.1, 62.0 ± 3.4 and 39.5 ± 4.9. Physico-chemical properties of the group of samples are reported elsewhere (Holt et al ., 1999).     

Physicochemical and sensory quality of several commercial Brazilian chocolate milk beverages

Five brands of Brazilian chocolate milk were subjected to physicochemical and acceptability analysis. The moisture content, fat content, pH and soluble solids content varied between 78.35 and 84.27 g/100 mL, 1.68 and 3.08 g/100 mL, 7.11 and 7.44, 14.0 and 19.0° Brix, respectively, while the ash contents and % lactic acid equivalents were similar. Four of the tested brands had acceptable scores in all attributes; however, one had lower acceptability scores and lower values for luminosity, chromaticity, b* and hue angle, which are potential indicators of the sensory quality. Strong chocolate aroma, strong chocolate flavour, strong brown colour, brightness and sandiness may be used as indicators of low acceptability for chocolate milk.     

Survival of Lactobacillus rhamnosus strains in the upper gastrointestinal tract

In the present study six probiotic Lactobacillus rhamnosus strains were investigated for their ability to survive in the human upper gastrointestinal tract through a dynamic gastric model of digestion. MRS broth was used as delivery vehicle and survival was investigated during in vitro gastric and gastric plus duodenal digestion. Results highlighted that all tested strains showed good survival rate during both gastric and duodenal digestion. In particular, three strains exhibited a great survival showing a recovery percentage in the range between 117 and 276%. In agreement with survival data, high lactic acid production was detected for all strains, confirming their metabolic activity during digestion.     

Evaluation of additional cooking procedures to achieve lethality microbiological performance standards for large, intact meat products

The U.S. Department of Agriculture Food Safety and Inspection Service (USDA-FSIS) has a specific lethality performance standard for ready-to-eat products. To assist meat processing establishments in meeting the performance standard, USDA-FSIS developed Appendix A, which provides guidelines for cooking temperatures, times, and relative humidity. This project determined whether the USDA-FSIS performance standards for lethality were met when using parameters other than those identified in Appendix A to cook large hams and beef inside rounds. The effects of alternative lethality parameters on the reduction of Salmonella Typhimurium and coliforms and on the toxin production of Staphylococcus aureus were evaluated. Large (9- to 12-kg) cured bone-in hams (n = 80) and large (8- to 13-kg) uncured beef inside rounds (n = 80) were used in this study. The products were subjected to 1 of 10 treatments defined by combinations of final internal product temperatures (48.9, 54.4, 60.0, 65.6, or 71.1°C) and batch oven relative humidities (50 or 90 % ). For all treatments, at least a 6.5-log reduction in Salmonella Typhimurium was achieved. The coliform counts were also substantially reduced for both hams and rounds. Across all treatments for both products, S. aureus toxin production was not detected. The relative humidity did not alter the lethality effectiveness for any of the treatments. The final internal temperatures and relative humidity combinations used in this project achieved the lethality performance standard established by USDA-FSIS for fully cooked, ready-to-eat products.     

Nutritional and health-related compounds in sprouts and seeds of soybean (<Emphasis Type="Italic">Glycine max</Emphasis>), wheat (<Emphasis Type="Italic">Triticum aestivum.L</Emphasis>) and alfalfa (<Emphasis Type="Italic">Medicago sativa</Emphasis>) treated by a new drying method

Nutritional and health-related compounds of alfalfa, wheat and soybean seeds dried by new drying process called the DIC process (controlled instantaneous pressure release) were evaluated, before and after sprouting. Vitamins (A, B₁, B₂, B₆, C and E), minerals (Fe, Mg, Ca, K, Mn, Na, Cu and Zn) and phytoestrogens (genistein and daidzein ) content were determined. Alfalfa, soybean and wheat seeds dried by DIC showed similar content of biological compounds to seeds dried by traditional processes. Sprouting DIC-seeds significantly increased the levels of vitamins, minerals and phytoestrogens, improving their nutrititional value and health quality compared to fresh products. The increase of 1250-fold and 10-fold of the initial vitamin A and vitamin C content, respectively, of alfalfa seeds due to sprouting is remarkable. Sprouts from DIC-seeds showed a significantly higher vitamin A content than sprouts obtained from seeds dried by other methods. Soybean sprouts obtained from DIC-seeds showed a significant increase in free phytoestrogens, quantified as genistein (70.34LJ.8 mg kg^-1 d.w.) and daidzein (109.17.3ᆥ.3 mg kg^-1 d.w.).