Microbial succession during Parmigiano-Reggiano cheesemaking was monitored by length heterogeneity PCR (LH-PCR), considering the intact and lysed cells at different stages of cheese production and ripening. When starter species underwent autolysis, species coming from milk were able to grow. For the first time, the LH-PCR technique was applied to study a fermented food.Parmigiano-Reggiano (PR) is a protected-designation-of-origin cheese, produced in specific areas of Northern Italy. It is a hard-textured, cooked, and long-ripened cheese made from raw cow's milk supplemented with natural whey starter rich in thermophilic lactic acid bacteria (LAB). Microbiological features of PR have been studied, isolating on traditional growth media a large number of strains from a large amount of samples representative of production and of the earlier and advanced stages of ripening (2, 3). Other studies have focused on the biodiversity of different strains of Lactobacillus helveticus isolated from natural whey cultures (6, 7). These previous studies showed the microbial biodiversity of PR but not its real microbial succession during production and ripening, and the use of culture-dependent methods could have underestimated the less-abundant components of microflora, which are equally important for cheese ripening and flavor development (15). Thus, the microbial ecology of PR still appears not to be completely understood. From this perspective, a detailed knowledge of LAB dynamics during the manufacturing and ripening stages is necessary for a deeper insight into the complex processes which contribute to the development of this appreciated cheese.In the present study, length heterogeneity PCR (LH-PCR) was used to monitor the microbial dynamics during 24 months of PR ripening for both the whole and lysed cells. The availability of PR twin wheels allowed us to have samples representative of the subsequent stages of the same cheesemaking process.In our opinion, the new findings in this article contribute to a better understanding of microbial dynamics in a complex fermented ecosystem.Cheesemaking. A unique cheese factory was selected for its equipment and technological conditions in order to obtain a suitable number of PR twin wheels. The same milk was distributed in equal volumes in eight vats and was worked according to PR production standards.Thirty-four liters of natural whey starter was added in each vat, containing 1,070 liters of milk (525 liters of partially skimmed evening milk and 545 liters of whole morning milk), bringing the pH of the mixture to 6.20. After cheesemaking and molding, the wheels, two from each vat, were held for 3 days and frequently turned to enable complete whey drainage. They were then salted by immersion in brine at 300 g NaCl ⅐ liter Ϫ1 for 23 days. Ripening was carried out in aging rooms with 85% relative humidity and a temperature of about 18°C for 24 months.Cheese sampling and bacterial recovery. Samples were collected from milk to cheese ripened for 24 months. Aliquots of the total mass of raw...

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-Parmigiano Reggiano is a Protected Designation of Origin, long-ripened cheese, made from cow's milk supplemented with natural whey starter, which thus contains a large microbial biodiversity. The aim of this study was to understand the population dynamics of the total lactic microflora throughout the manufacture and ripening of this cheese. Several approaches were combined to determine the quantitative changes in the different bacterial populations during 20 months of ripening of Parmigiano Reggiano cheeses from the same cheesemaking. Total and viable cells were enumerated after fluorescent labeling. Culturable bacteria were enumerated on different plate count agar media, including original media prepared from curd and ripened cheese. Six peptidase activities were quantified in curd and cheese samples free from cells. While the total bacterial cultivable population remained high and similar for the first six months, a decrease in viable starter lactic acid bacteria was observed during the first 48 h. The non-starter lactic acid bacteria populations, initially present in low numbers, began to grow after the brining and remained at high levels (about 10 7 CFU·g −1 ) for at least 10 months. During ripening, a strong decrease in the total bacterial population and a marked increase in 4 out of 6 peptidase activities were observed. In the external and internal zones of Parmigiano Reggiano cheese different trends in microbial growth, cell autolysis and peptidase activity were observed. This study gives for the first time a global view of the possible contribution of total, viable, cultivable and lysed bacterial cells throughout the ripening of Parmigiano Reggiano cheese.Parmigiano Reggiano cheese / ripening / lactic acid microflora / bacterial cell lysis / cell viability / peptidase activity

Background: Fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) are an heterogeneous group of compounds that can be poorly digested and may have a range of effects on gastrointestinal processes. FODMAPs are found in a wide variety of foods, including bread. FODMAPs’ intake is associated with the onset of symptoms of irritable bowel syndrome (IBS). On the other hand, some FODMAPs contribute to the healthy maintenance of intestinal microbiota. Volume increase of bread dough commonly relies on the use of two biological leavening agents, sourdough and baker’s yeast and, in some cases, a combination of both.Scope and Approach: The main objective of this review is to discuss the association between FODMAPs and IBS, beneficial effects of FODMAPs on healthy subjects and potential impact of biological leavening agents on FODMAPs content of bread.Key Findings and Conclusion: Given that yeasts and lactic acid bacteria, the dominant microorganisms in sourdough, may degrade FODMAPs, it would be possible to modulate the FODMAPs concentration in bread, thus positively affecting consumers’ health.

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