Novel insights on pink discoloration in cheese: The case of Pecorino Toscano

Pink discoloration in cheese has been the subject of wide research, but the basis for this phenomenon remains elusive. This defect impacts a wide range of ripened cheeses, resulting in the rejection of cheese and a consequent economic loss for dairy industries. As multiple causes for pink discoloration have been reported for different cheeses in the literature, the aim of this research was to investigate the cause of a pink discoloration found on Pecorino Toscano cheese rind. The results of microbiological analysis revealed the presence of high microbial counts associated to the rind and the nearest inner part. Strains isolated from the coloured part were mainly identified as Serratia liquefaciens, suggesting that an environmental contamination of the cheese rind by this species could be the cause of the observed defect and expanding the knowledge related to pink discoloration in cheeses

Eating fermented: Health benefits of lab-fermented foods

Lactic acid bacteria (LAB) are involved in producing a considerable number of fermented products consumed worldwide. Many of those LAB fermented foods are recognized as beneficial for human health due to probiotic LAB or their metabolites produced during food fermentation or after food digestion. In this review, we aim to gather and discuss available information on the health-related effects of LAB-fermented foods. In particular, we focused on the most widely consumed LAB-fermented foods such as yoghurt, kefir, cheese, and plant-based products such as sauerkrauts and kimchi

Influence of Processing Parameters and Natural Antimicrobial on Alicyclobacillus acidoterrestris and Clostridium pasteurianum Using Response Surface Methodology

The food industry must ensure the stability of the products, and this is often achieved by exposing foods to heat treatments that are able to ensure the absence of pathogenic or spoilage microorganisms. These treatments are different in terms of temperature and duration and could lead to a loss in nutritional and sensory value. Moreover, some types of microorganisms manage to survive these treatments thanks to the sporification process. The addition of antimicrobials can become necessary, but at present, consumers are more inclined toward natural products, avoiding synthetic and chemical additives. Antimicrobials from plants could be a valuable option and, in this context, a patent concerning an antimicrobial extract from fermented plant substrate was recently tested against foodborne pathogens revealing high antimicrobial activity. The objective of this study was the creation of a model for the evaluation and subsequent prediction of the combined effect of different process and product variables, including antimicrobial addition, on the inhibition and reduction of spore germination of target microorganisms, Alicyclobacillus acidoterrestris and Clostridium pasteurianum, responsible for spoilage of tomato-based products

Draft genome sequence of lactobacillus helveticus Lh 23, isolated from natural whey starter

Lactobacillus helveticus is a thermophilic lactic acid bacterium that is widely employed as a starter culture for manufacturing several Swiss and Italian hard-cooked cheeses. The sequencing of L. helveticus Lh 23, which consists of 2,100,230 bp with a GC content of 36.5%, reveals industrially useful traits and interesting metabolic pathways

Exploration of Gate Trench Module for Vertical GaN devices

The aim of this work is to present the optimization of the gate trench module for use in vertical GaN devices in terms of cleaning process of the etched surface of the gate trench, thickness of gate dielectric and magnesium concentration of the p-GaN layer. The analysis was carried out by comparing the main DC parameters of devices that differ in surface cleaning process of the gate trench, gate dielectric thickness, and body layer doping. . On the basis of experimental results, we report that: (i) a good cleaning process of the etched GaN surface of the gate trench is a key factor to enhance the device performance, (ii) a gate dielectric >35-nm SiO2 results in a narrow distribution for DC characteristics, (iii) lowering the p-doping in the body layer improves the ON-resistance (RON). Gate capacitance measurements are performed to further confirm the results. Hypotheses on dielectric trapping/detrapping mechanisms under positive and negative gate bias are reported.Comment: 5 pages, 10 figures, submitted to Microelectronics Reliability (Special Issue: 31st European Symposium on Reliability of Electron Devices, Failure Physics and Analysis, ESREF 2020

Lysozyme side effects in Grana Padano PDO cheese: new perspective after 30 years using

Since thirty years, hen\u2019s egg white lysozyme is in use as an anti-clostridial agent in Grana Padano PDO cheese manufacturing in order to avoid the cheese blowing defect. However, as the EU legislation includes egg among allergens, Grana Padano falls into the category of food products containing allergens. In view of discontinuing this situation, this work aimed to investigate the effects of abandoning lysozyme use on cheese characteristics. Nine manufacturing processes, conducted with and without lysozyme, were monitored from milk to ripened cheese at four different dairies. Both the lactic acid bacteria microbiota (LAB) and chemical parameters related to cheese maturation were evaluated. The presence of the enzyme seems to affect the capacity of some LAB species and biotypes to grow in cheese during ripening. Accordingly, primary proteolysis was not affected, whereas differences were found in amino acids release that could be traced back to the lysozyme-dependent LAB growth

Compact Modeling of Nonideal Trapping/Detrapping Processes in GaN Power Devices

Compact modeling of charge trapping processes in GaN transistors is of fundamental importance for advanced circuit design. The goal of this article is to propose a methodology for modeling the dynamic characteristics of GaN power HEMTs in the realistic case where trapping/detrapping kinetics are described by stretched exponentials, contrary to ideal pure exponentials, thus significantly improving the state of the art. The analysis is based on: 1) an accurate methodology for describing stretched-exponential transients and extracting the related parameters and 2) a novel compact modeling approach, where the stretched exponential behavior is reproduced via multiple RC networks, whose parameters are specifically tuned based on the results of 1). The developed compact model is then used to simulate the transient performance of the HEMT devices as a function of duty cycle and frequency, thus providing insight on the impact of traps during the realistic switching operatio

Lysozyme affects the microbial catabolism of free arginine in raw-milk hard cheeses

Lysozyme (LZ) is used in several cheese varieties to prevent late blowing which results from fermentation of lactate by Clostridium tyrobutyricum. Side effects of LZ on lactic acid bacteria population and free amino acid pattern were studied in 16 raw-milk hard cheeses produced in eight parallel cheese makings conducted at four different dairies using the same milk with (LZ\ufe) or without (LZ-) addition of LZ. The LZ-cheeses were characterized by higher numbers of cultivable microbial population and lower amount of DNA arising from lysed bacterial cells with respect to LZ \ufe cheeses. At both 9 and 16 months of ripening, Lactobacillus delbrueckii and Lactobacillus fermentum proved to be the species mostly affected by LZ. The total content of free amino acids indicated the proteolysis extent to be characteristic of the dairy, regardless to the presence of LZ. In contrast, the relative patterns showed the microbial degradation of arginine to be promoted in LZ \ufe cheeses. The data demonstrated that the arginine-deiminase pathway was only partially adopted since citrulline represented the main product and only trace levels of ornithine were found. Differences in arginine degradation were considered for starter and non-starter lactic acid bacteria, at different cheese ripening stages