The purpose of this paper is to 1) understand the cheesemaking process practiced in Sardinia, 2) analyze how the people utilized the ecology to mature cheeses in the summer heat, and 3) discuss the history of the development of matured cheeses in Sardinia, Italy. The matured hard cheese named Casu crudu (S)/Fiore Sardo (I) has processed in Sardinia by the pasta cruda method. The transhumant pastoralists in Sardinia used to immediately sell or consume the freshly-made cheeses in the winter and spring when they resided in the lowland. It was also possible to mature cheeses in the lowland, because the temperature was low in the winter and spring. In the hot and dry summer, they migrated to the highland and made matured cheeses as they utilized the cold environment of the highland and their cool residence. They coated the cheese surfaces with olive oil to keep the cheeses from drying and succeeded in maturing the cheeses. They were able to mature cheeses and cope with the Mediterranean climate of hot and dry summer by skillfully utilizing the vertical migration from their year-round transhumance. The geography of Sardinia (comprising of lowland and highland of over 1,000 m above sea level), use of the environment (grazing in the lowland in the winter and fall and in the highland in the summer), and the transhumant lifestyle all contributed to the creation of matured hard cheeses unique to Sardinia.
Lowering of deoxycholic acid (DCA, categorized as a secondary bile acid) concentrations is important to preventing the DCA-induced diseases to extend and improve the quality of life. We examined DCA-lowering activity of two probiotic bacteria, Bifidobacterium longum SBT2928 and Lactobacillus gasseri SBT2055, in vitro. The two strains significantly removed DCA in a distinctive manner, although they removed only a trace amount of cholic acid, a precursor of DCA. B. longum SBT2928 required saccharides for this activity, with about 50% of 1 mM DCA substrate removed when 0.65％ lactose was added. The amount of removed DCA when lactose was added was more than those when glucose or galactose were added. We postulated that the mechanism of action was incorporation of DCA into cells, which was promoted by the addition of saccharides as a driving force. Further examinations showed that the rate of DCA reduction was dependent on the concentration of lactose and this reduction activity was effective even when raffinose or lactulose, which are accessible in the colon, were added as oligosaccharides. L. gasseri SBT2055 removed about 25％ of 1 mM DCA substrate, independently of saccharides. We postulated that the mechanism of action was adhesion to cell surfaces. LiCl treatment did not affect DCA-lowering activity, whereas heat treatment reduced it. We expect that these strains contribute to the protection against various DCA-induced diseases.
Limited studies have been reported on which commercially available oligosaccharides mixture of some different structures are selectively consumed by each bifidobacterial species or strains. Therefore, we compared the consumption of the commercial oligosaccharides including GOS, Lactosucrose (LS), Fructooligosaccharide (FOS), Fibrooligosaccharide (Fib), Isomaltooligosaccharide (IMO), Gentiooligosaccharide (GEO), Nigerooligosaccharide (NOS), Xylooligosaccharide (XOS) by 16 strains of 7 species of bifidobacteria, using lactose as a reference.
All 16 strains grew well in the broth containing each of lactose, GOS, LS, NOS, or GEO as an only carbon source, while 2 species of B. breve and 4 strains of B. bifidum did not well with FOS, and 4 strains of B. breve and 4 strains of B. bifidum did not well with FOS and Fib. None of the 10 strains out of B. breve, B. bifidum, and B. longum subsp. infantis did grow with XOS, while the strains of B. adolescentis and B. longum subsp. longum grew at slow rate. The three of four B. bifidum strains did not grow with ISO. Based on determination of the residual carbohydrates in the supernatants of the growth medium, it was shown that lactose, GOS and LS were completely utilized by the all bifidobacterial strains, whereas some monosaccharides accumulated in the broth. Some bifidobacterial strains did not utilize the oligosaccharides in IMO and FOS. As a larger amount of free Glc exists in NOS and GEO, it was assumed that the bifidobacterial strains prefer Glc to the disaccharides or trisaccharides for their growth.
Fermented dairy products are familiar foods that humans have prepared and consumed for millennia. In later years, there have been many reports regarding the physiological functions of lactic acid bacteria and the peptides and fatty acids generated during the fermentation of milk or cheese. Particularly, several recent studies have elucidated the effects of fermented dairy products on cognitive function. Epidemiological and clinical evidence has indicated that fermented dairy products have preventive effects against dementia, and preclinical studies have identified individual molecules generated during fermentation that are responsible for those preventive effects. In this review, the protective effects of fermented dairy products and their components on cognitive function and their prospects for future clinical development will be discussed.