Microbial dynamics of model Fabriano-like fermented sausages as affected by starter cultures, nitrates and nitrites.

The present study promotes the valorization of Fabriano-like fermented sausages, which are central-Italy salami with an origin that dates to the early 17th century, for the possible future selection of autochthonous starter cultures to be used with respect to local traditions. To the best of the authors' knowledge, this study represents the first attempt to define the microbial dynamics in Fabriano-like fermented sausage and the effect of nitrates/nitrites and starter cultures on its natural bacterial biota. Culture and RNA-based techniques (RT-PCR-DGGE and Illumina sequencing) were used to assess the microbial ecology of model Fabriano-like fermented sausages together with the impact of starter cultures and different nitrate and nitrite concentrations. The meat batter was used to produce two batches of fermented sausages that were prepared as follows: i) without commercial starters or ii) with the use of starter cultures composed of Pediococcus pentosaceus and Staphylococcus xylosus. Each batch was further divided into three different batches with the addition of 0/0 mg kg-1 nitrate/nitrite, 75/60 mg kg-1 nitrate/nitrite and 150/125 mg kg-1 nitrate/nitrite to the first, second and third batch, respectively. The samples, which were produced in triplicate, were analyzed on the day of production and after 7, 21, and 42 days of ripening. Enterobacteriaceae counts were always higher in model Fabriano-like sausages produced without the use of starter cultures at all of the sampling times irrespective of the tested nitrate/nitrite concentrations. Lactobacilli counts were positively influenced by the starters, although this influence was not evident over time; moreover, the effect of nitrates and nitrites on the counts of lactobacilli differed over time. As a general trend, coagulase-negative cocci counts were apparently not influenced by the tested nitrate/nitrite concentrations. Regarding the effect of nitrates/nitrites on the microbial diversity revealed by RT-PCR-DGGE, the higher the concentration, the lower the presence of some genera/species such as Pseudomonas spp., Serratia liquefaciens and Staphylococcus spp. However, Illumina sequencing detected Pseudomonas spp. as a minority species after 7, 21 and 42 days of ripening irrespective of the nitrate/nitrite concentration. The presence of Staphylococcus species was highlighted by both RT-PCR-DGGE and Illumina sequencing at all of the stages of ripening, although its presence was massively detected in fermented sausages produced without the use of nitrates/nitrites at the end of ripening. Overall, the data collected clearly highlighted the dominance of Lactobacillus sakei in all of the fermented sausages during ripening (from day 7 to day 42) and irrespective of the nitrate/nitrite concentration and added starter cultures. Moreover, Pediococcus spp. was principally detected in model Fabriano-like fermented sausage with added starter cultures irrespective of the nitrate/nitrite concentration.

Impact of thistle rennet from Carlina acanthifolia All. subsp. acanthifolia on bacterial diversity and dynamics of a specialty Italian raw ewes' milk cheese.

Caciofiore della Sibilla is an Italian specialty soft cheese manufactured with Sopravissana raw ewes' milk and thistle rennet prepared with young fresh leaves and stems of Carlina acanthifolia All. subsp. acanthifolia, according to an ancient tradition deeply rooted in the territory of origin (mountainous hinterland of the Marche region, Central Italy). In this study, the impact of thistle rennet on the bacterial dynamics and diversity of Caciofiore della Sibilla cheese was investigated by applying a polyphasic approach based on culture and DNA-based techniques (Illumina sequencing and PCR-DGGE). A control cheese manufactured with the same batch of ewes' raw milk and commercial animal rennet was analyzed in parallel. Overall, a large number of bacterial taxa were identified, including spoilage, environmental and pro-technological bacteria, primarily ascribed to Lactobacillales. Thistle rennet was observed clearly to affect the early bacterial dynamics of Caciofiore della Sibilla cheese with Lactobacillus alimentarius/paralimentarius and Lactobacillus plantarum/paraplantarum/pentosus being detected in the phyllosphere of C. acanthifolia All., thistle rennet and curd obtained with thistle rennet. Other bacterial taxa, hypothetically originating from the vegetable coagulant (Enterococcus faecium, Lactobacillus brevis, Lactobacillus delbrueckii, Leuconostoc mesenteroides/pseudomesenteroides), were exclusively found in Caciofiore della Sibilla cheese by PCR-DGGE. At the end of the maturation period, Illumina sequencing demonstrated that both cheeses were dominated by Lactobacillales; however curd and cheese produced with thistle rennet were co-dominated by Lactobacillus and Leuconostoc, whereas Lactoccous prevailed in curd and cheese produced with commercial animal rennet followed by Lactobacillus. Differences in the bacterial composition between the two cheeses at the end of their maturation period were confirmed by PCR-DGGE analysis.

Occurrence of antibiotic resistance genes in the fecal DNA of healthy omnivores, ovo-lacto vegetarians and vegans.

SCOPE: The effects of long-term omnivore, ovo-lacto vegetarian and vegan diets on the occurrence of 12 antibiotic resistance (AR) genes in the human gut were studied. METHODS AND RESULTS: The feces of 144 healthy volunteers recruited from Turin, Bari, Bologna, and Parma were screened for the occurrence of genes conferring resistance to tetracyclines, macrolide-lincosamide-streptogramin B, vancomycin, and ß-lactams. Overall, erm(B), tet(W) and tet(M) were detected at the highest frequency. A low effect from the diet on the AR gene distribution emerged, with tet(K) and vanB occurring at a lower and higher frequency in vegans and omnivores, respectively. A correlation of the intake of eggs, milk from animal sources and cheese with an increased occurrence of tet(K) was observed, together with a higher incidence of vanB in consumers of eggs, poultry meat, fish and seafood. When the detection frequencies of AR genes in volunteers from Bari and the other sites were comparatively evaluated, a north-to-south gradient was observed, whereas no effect of sex or age was highlighted. Except for tet(K), a negligible three-factor interaction was seen. CONCLUSION: A high impact of the geographical location on AR gene distribution was seen in the cohort of subjects analyzed, irrespective of their dietary habits.

Oil Characteristics of Four Palestinian Olive Varieties.

Olive oil represents an important source of income for Palestinian farmers in local, national and international markets. Sometimes, olive oil produced in local climatic conditions, does not achieve the International Olive Council (IOC) trade standards so that international markets are precluded. The oil chemical composition and sensory profile of four Palestinian olive varieties (Nabali Baladi, Nabali Mohassan, Souri and K18) were characterized in 2010 throughout an in situ evaluation. Most of the physicchemical characteristics and the fatty acid composition of the varieties met the International Olive Council trade standards (IOC-TS) for extra virgin olive oils. Values of K270 for Nabali Baladi and linolenic acid for Souri slightly exceeded the limit. Eicosanoic acid exceeded the IOC-TS limits in the oils of all considered varieties. Among the sterols, the Δ-7-stigmastenol resulted too high for Nabali Baladi and Souri. Sensory profile for the tested varieties showed a reminiscence of tomato or artichoke and light to medium bitter and pungent sensations. Results represent an important baseline reference for further studies about oil composition and quality of the main Palestinian olive germplasm and provide indication of potential critical points to be controlled in order to ensure the full achievement of IOC-TS and access international markets.

Microbial Diversity of Type I Sourdoughs Prepared and Back-Slopped with Wholemeal and Refined Soft (Triticum aestivum) Wheat Flours.

The fermentation of type I sourdough was studied for 20 d with daily back-slopping under laboratory and artisan bakery conditions using 1 wholemeal and 2 refined soft wheat (Triticum aestivum) flours. The sourdough bacterial and yeast diversity and dynamics were investigated by plate counting and a combination of culture-dependent and culture-independent PCR-DGGE approach. The pH, total titrable acidity, and concentration of key organic acids (phytic, lactic, and acetic) were measured. Three flours differed for both chemical and rheological properties. A microbial succession was observed, with the atypical sourdough species detected at day 0 (i.e. Lactococcus lactis and Leuconostoc holzapfelii/citreum group for bacteria and Candida silvae and Wickerhamomyces anomalus for yeasts) being progressively replaced by taxa more adapted to the sourdough ecosystem (Lactobacillus brevis, Lactobacillus alimentarius/paralimentarius, Saccharomyces cerevisiae). In mature sourdoughs, a notably different species composition was observed. As sourdoughs propagated with the same flour at laboratory and artisan bakery level were compared, the influence of both the substrate and the propagation environment on microbial diversity was assumed.

Yeast and mould dynamics in Caciofiore della Sibilla cheese coagulated with an aqueous extract of Carlina acanthifolia All.

Caciofiore della Sibilla is a speciality ewes' milk cheese traditionally manufactured in a foothill area of the Marche region (Central Italy) with a crude extract of fresh young leaves of Carlina acanthifolia All. subsp. acanthifolia as a coagulating agent. The fungal dynamics and diversity of this speciality cheese were investigated throughout the manufacturing and 20-day ripening process, using a combined PCR-DGGE approach. The fungal biota of a control ewes' milk cheese, manufactured with the same batch of milk coagulated with a commercial animal rennet, was also monitored by PCR-DGGE, in order to investigate the contribution of the peculiar vegetable coagulant to the fungal diversity and dynamics of the cheese. Based on the overall results collected, the raw milk and the dairy environment represented the main sources of fungal contamination, with a marginal or null contribution of thistle rennet to the fungal diversity and dynamics of Caciofiore della Sibilla cheese. Copyright © 2016 John Wiley & Sons, Ltd.