The influence of calf (R1), kid (R2) and pig (R3) rennets on microbiota, biogenic amines (BAs) and γ-aminobutyric acid (GABA) accumulation in raw milk ewe’s cheeses was evaluated. Cheeses were investigated at different ripening times for their microbial composition, free amino acids (FAAs), BAs and GABA content. Moreover, the expression of tyrosine (tdc) and histidine (hdc) decarboxylases genes was evaluated by quantitative Real Time–Polymerase Chain Reaction (qRT-PCR). Microbial counts showed similar values in all samples. Pig rennet were cheeses were characterized by higher proteolysis and the highest values of BAs. The BAs detected were putrescine, cadaverine and tyramine, while histamine was absent. qRT-PCR confirmed this data, in fact hdc gene was not upregulated, while tdc gene expression increased over time in agreement with the increasing content of tyramine and the highest fold changes were detected in R3 cheeses. GABA showed the highest concentration in R2 cheeses reaching a value of 672 mg/kg. These results showed that the accumulation of BAs and GABA in Pecorino di Farindola is influenced by ripening time and type of coagulant. Further studies are required to develop starter cultures to reduce BAs content and improve health characteristics of raw milk ewe’s cheeses.

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Irrigation is widely used for the production of table olives because it increases fruit size and yield. However, irrigation also determines less accumulation of total phenols, an increase in water content, a decrease of firmness, lower concentrations of soluble sugars in the mesocarp, thus positively or negatively affecting the fermentation process for the production of table olives. In this study we tested the hypothesis that green fruits of cultivar Itrana obtained by different irrigation regimes had different phenolic concentration that responded differentially to spontaneous or inoculated fermentation. Fruits were harvested from two orchards in the Latina province of Latium, Italy, which had been irrigated with different volumes of water during the growing season to compare the evolution of spontaneous and inoculated fermentation processes. We measured fruit characteristics at harvest, changes in the concentrations of secoiridoids and lignans, and main microbial groups abundance during fermentation. At harvest and during fermentation the concentration of phenolic compounds was higher in fruits sampled from trees that had received less water in the field. Differences were observed between spontaneous and inoculated fermentations, with a prevalence of lactic acid bacteria (LAB) in inoculated samples. In particular, oleuropein concentration completely disappeared only from samples inoculated with the two selected strains used as starters. The inoculum with selected LAB positively influenced the fermentation process of green olives, whereas the irrigation regime previously experienced by trees did not alter fermentation.

In this study, yeasts isolated from filter membranes used for the quality control of bottled wines were identified and tested for their resistance to some cleaning agents and potassium metabisulphite, adhesion to polystyrene and stainless-steel surfaces, and formation of a thin round biofilm, referred to as a MAT. A total of 40 strains were identified by rRNA internal transcribed spacer (ITS) restriction analysis and sequence analysis of D1/D2 domain of 26S rRNA gene. Strains belong to Pichia manshurica (12), Pichia kudriavzevii (9), Pichia membranifaciens (1), Candida sojae (6), Candida parapsilosis (3), Candida sonorensis (1), Lodderomyces elongisporus (2), Sporopachydermia lactativora (3), and Clavispora lusitaniae (3) species. Regarding the adhesion properties, differences were observed among species. Yeasts preferred planktonic state when tested on polystyrene plates. On stainless-steel supports, adhered cells reached values of about 6 log CFU/mL. MAT structures were formed only by yeasts belonging to the Pichia genus. Yeast species showed different resistance to sanitizers, with peracetic acid being the most effective and active at low concentrations, with minimum inhibitory concentration (MIC) values ranging from 0.08% (v/v) to 1% (v/v). C. parapsilosis was the most sensible species. Data could be exploited to develop sustainable strategies to reduce wine contamination and establish tailored sanitizing procedures.

Aims Kluyveromyces marxianus dairy strains were tested for γ‐aminobutyric acid (GABA) production. The genes involved in GABA catabolism (UGA1 and UGA2) and anabolism (GAD1) were found in K. marxianus genome. Their relative expression was evaluated with primer designed ad hoc. Methods and Results Strains were grouped on the basis of GAD1 gene sequence. Representative strains for each group were tested for GABA production by high‐performance liquid chromatography. All strains produced it at low levels. qRT‐PCR showed the absence of a relation between GABA production and GAD1 gene expression. UGA1 and UGA2 genes were not upregulated and low amounts of succinic acid were detected. Conclusions All strains released a low amount of GABA suggesting that probably it was stored within cells. The different behaviour of strains in terms of GABA and succinic acid production as well as gene expression highlighted the genetic and phenotypic biodiversity of this species. Significance and Impact of the Study GABA production and genes involved in its catabolism and anabolism were described in a population of dairy K. marxianus for the first time. The variability observed in terms of genetic and phenotypic biodiversity is important especially to exploit this non‐conventional yeast as microbial platform.

Iodine is an essential trace element involved in the regulation of thyroid metabolism and antioxidant status in humans and animals. The aim of this study was to evaluate the effect of ewes’ dietary iodine supplementation on biogenic amines content as well as microbiological and physico-chemical characteristics in a raw milk cheese at different ripening times (milk, curd, and 2, 7, 15, 30, 60, and 90 days). Two cheese-making trials were carried out using milk from ewes fed with unifeed (Cheese A) or with the same concentrate enriched with iodine (Cheese B). The results indicated that the counts of principal microbial groups and physico-chemical characteristics were quite similar in both cheeses at day 90. Cheese B was characterized by a higher content of biogenic amines and propionic acid. Propionic bacteria were found in both cheeses mainly in Trial B in agreement with the higher content of propionic acid detected.