The Impact of Different Hop Compounds on the Growth of Selected Beer Spoilage Bacteria
Beer-spoiling lactic acid bacteria are a major reason for quality complaints in breweries around the world. Spoilage by a variety of these bacteria can result in haze, sediment, slime, off flavors, and acidity. Using certain hop products that inhibit the growth of these spoilers could be a solution. To investigate the impact of seven different hop compounds on the growth of six major beer spoilage bacteria, two concentrations (10 mg/L and 25 mg/L) of each hop substance were added to unhopped beer. The potential growth of the spoilage bacteria was investigated over 56 consecutive days. A comparison of the results shows a strong inhibition of growth of all spoilage bacteria at 25 mg/L of tetrahydro‐iso‐α‐acids, closely followed by α‐acids as the second most inhibitory substance. The results showed a high resistance of L. brevis to all hop compounds, as well as an inhibition of L. coryniformis and L. buchneri at low concentrations of most hop components. In comparison with the control sample, L. lindneri showed increased growth in the presence of some hop compounds. Journal of the Institute of Brewing. Published September 11, 2020. DOI: 10.1002/jib.624.
Rapid Method Detection of E. coli and Coliforms in Dairy Products
This investigation’s goal was to develop colorimetric tests for rapid detection of E. coli/coliforms. These tests were developed using the modified E. coli selective medium (M‐ECSM) and coliform selective medium, respectively. The selective media contain a combination of group-specific marker enzymes and selective agents. The marker enzymes were screened using chromogenic substrates wherein β‐D‐glucuronidase and glutamate decarboxylase were found specific for E. coli, with β‐D‐galactosidase specific for coliforms. The selectivity of the media was achieved using different concentrations of ampicillin and gentamicin. A field evaluation of the tests reported the prevalence of E. coli/coliforms as 57.29/88.54% in 96 raw milk samples and 16.28/51.16% in 43 pasteurized milk samples. Test components were vacuum dried in the form of miniaturized point‐of‐need tests for field application in dairy farms and industries with minimal infrastructural requirements. Journal of Food Safety. 2020;e12839.
The stretching conditions adopted for mozzarella cheese production are important, as they have a direct effect on the texture and thermophysical properties of cheese. The aim of this study was to evaluate the effect of stretching temperature on the microstructure, texture, and thermophysical properties of mozzarella cheese throughout the refrigerated storage period. The microstructure, apparent zeta potential, uniaxial compression, texture profile analysis, melting, and free oil of cheeses stretched with water at 75°C and 85°C were analyzed during 28 days of storage at 4°C. The results showed that the variation in the stretching temperature did not cause changes in the melting and oil release of the cheeses. The visual analysis of fat particles size showed changes throughout the refrigerated storage period, but with no impact in the free oil release from the cheeses. Journal of Food Processing and Preservation. 2020;e14703.
The core objective of this study was to enhance the storage stability of apples with cinnamon essential oil edible coating. Apples were coated with coating material containing different concentrations of cinnamon essential oil. Coated apples were packed in polypropylene bags and stored at 5°C refrigeration for two months. The coated apples were subjected to physiochemical analysis (moisture loss percentage, weight loss, color, total soluble solids, ascorbic acid, titratable acidity, and pH), microbial analysis (antifungal activity and antimicrobial activity), and sensory evaluation during storage after intervals of 10 days for two months. During storage, a rapid decrease in all parameters was observed, except in the group with 5% cinnamon essential oil. The edible coating contained in this group showed the highest zone of inhibition against P. expansum and E. coli and prevented the spoilage and maintained the nutritional values of the apples. Journal of Food Processing and Preservation. 2020;e14926.