Metabolic responses of Lactobacillus plantarum strains during fermentation and storage of vegetable and fruit juices.

Strains of Lactobacillus plantarum were grown and stored in cherry (ChJ), pineapple (PJ), carrot (CJ), and tomato (TJ) juices to mimic the chemical composition of the respective matrices. Wheat flour hydrolysate (WFH), whey milk (W), and MRS broth were also used as representatives of other ecosystems. The growth rates and cell densities of L. plantarum strains during fermentation (24 h at 30°C) and storage (21 days at 4°C) differed only in part, being mainly influenced by the matrix. ChJ and PJ were the most stressful juices for growth and survival. Overall, the growth in juices was negatively correlated with the initial concentration of malic acid and carbohydrates. The consumption of malic acid was noticeable for all juices, but mainly during fermentation and storage of ChJ. Decreases of branched-chain amino acids (BCAA)-with the concomitant increase of their respective branched alcohols-and His and increases of Glu and gamma-aminobutyric acid (GABA) were the main traits of the catabolism of free amino acids (FAA), which were mainly evident under less acidic conditions (CJ and TJ). The increase of Tyr was found only during storage of ChJ. Some aldehydes (e.g., 3-methyl-butanal) were reduced to the corresponding alcohols (e.g., 3-methyl-1-butanol). After both fermentation and storage, acetic acid increased in all fermented juices, which implied the activation of the acetate kinase route. Diacetyl was the ketone found at the highest level, and butyric acid increased in almost all fermented juices. Data were processed through multidimensional statistical analyses. Except for CJ, the juices (mainly ChJ) seemed to induce specific metabolic traits, which differed in part among the strains. This study provided more in-depth knowledge on the metabolic mechanisms of growth and maintenance of L. plantarum in vegetable and fruit habitats, which also provided helpful information to select the most suitable starters for fermentation of targeted matrices.

Use of microparticulated whey protein concentrate, exopolysaccharide-producing Streptococcus thermophilus, and adjunct cultures for making low-fat Italian Caciotta-type cheese.

Low-fat Caciotta-type cheeses were manufactured with partially skim milk (fat content of ~0.3%) alone (LFC); with the supplementation of 0.5% (wt/vol) microparticulated whey protein concentrate (MWPC) (LFC-MWPC); with MWPC and exopolysaccharides (EPS)-producing Streptococcus thermophilus ST446 (LFC-MWPC-EPS); and with MWPC, EPS-producing strain ST446, and Lactobacillus plantarum LP and Lactobacillus rhamnosus LRA as adjunct cultures (LFC-MWPC-EPS-A). The non-EPS-producing isogenic variant Streptococcus thermophilus ST042 was used for making full-fat Caciotta-type cheese (FFC), LFC, and LFC-MWPC. Cheeses were characterized based on compositional, microbiological, biochemical, texture, volatile components (purge and trap, and solid-phase microextraction coupled with gas chromatography-mass spectrometry), and sensory analyses. Compared with FFC and LFC (51.6 ± 0.7 to 53.0 ± 0.9%), the other cheese variants retained higher levels of moisture (60.5 ± 1.1 to 67.5 ± 0.5%). The MWPC mainly contributed to moisture retention. Overall, all LFC had approximately one-fourth (22.6 ± 0.8%) of the fat of FFC. Hardness of cheeses slightly varied over 7d of ripening. Microbial EPS positively affected cheese texture, and the texture of LFC without MWPC or microbial EPS was excessively firm. Free amino acids were at the highest levels in LFC treatments (2,705.8 ± 122 to 3,070.4 ± 123 mg/kg) due to the addition of MWPC and the peptidase activity of adjunct cultures. Aldehydes, alcohols, ketones, sulfur compounds, and short- to medium-chain carboxylic acids differentiated LFC variants and FFC. The sensory attributes pleasant to taste, intensity of flavor, overall acceptability, and pleasant to chew variously described LFC-MWPC-EPS and LFC-MWPC-EPS-A. Based on the technology options used, low-fat Caciotta-type cheese (especially ripened for 14 d) has promising features to be further exploited as a suitable alternative to the full-fat variant.

Characterization of Italian cheeses ripened under nonconventional conditions.

Four Italian cheeses (Casciotta di Urbino, Barricato San Martino, Vento d'Estate, and Ubriaco di Raboso) nonconventionally ripened under different plant materials (walnut leaves, herbs, hay, and wine by-products, respectively) were compared for compositional, microbiological, biochemical, and volatile profile characteristics. Mean values for gross composition were rather similar. Because primary starters were not used for manufacture, the endogenous lactic acid bacteria were mainly present (7.0 to 9.0 log10 cfu/g). Except for Lactobacillus paracasei and Leuconostoc mesenteroides, which were commonly identified in 3 cheeses, Lactococcus lactis, Enterococcus sanguinicola, Lactobacillus brevis, Enterococcus durans/Enterococcus faecium, Lactobacillus plantarum, and Weissella cibaria/Weissella confusa were variously found in the 4 cheeses. Random amplification of polymorphic DNA-PCR analysis showed the biodiversity among the strains, and the species of lactobacilli were in part grouped according to their origin. As shown by the principal component analysis of reverse-phase fast protein liquid chromatography data for the pH 4.6-soluble fractions and by the determination of free AA, the secondary proteolysis of Barricato San Martino and Vento d'Estate mainly differed from the other 2 cheeses. Purge-and-trap and solid-phase microextraction were coupled with gas chromatography-mass spectrometry to determine volatile compounds. Vento d'Estate showed the highest levels of almost all chemical classes, and Casciotta di Urbino was characterized by a very low level of volatile components. Esters, ketones, and terpenes were the chemical classes that mainly differentiated the cheeses. Several volatile compounds seemed to be released directly from the plant materials used for ripening, especially terpenes for Vento d'Estate cheese. The lowest level of volatile free fatty acids was found in Casciotta d'Urbino, in which rennet paste was not used during manufacture. The highest concentration of free fatty acids, especially butyric and caproic acids, was found in Vento d'Estate cheese.

Influence of the composition of Alpine highland pasture on the chemical, rheological and sensory properties of cheese.

A study was undertaken to compare the chemical and sensory characteristics of Abondance cheeses made with milk from animals grazing areas within the same highland pasture, but with different predominant plants. Nine cheeses made during the last 3 d of three successive 7 d periods were evaluated. The animals grazed on the southern side of the highland pasture during the first period (15-21 June), on the northern side during the second period (22-29 June) and returned to the southern side for the third period (30 June-6 July). The gross composition of the cheeses did not vary between periods. 'North' cheeses contained more plasmin, gamma-casein, alpha s1-I-casein and water-soluble N than 'south' cheeses. Both sensory and instrumental measurements indicated that north cheeses were less firm, stickier and more easily fractured than south cheeses. North cheeses were also more salty, bitter and persistent. Their overall aroma was more intense and they had more intense sour, burnt, toasted, fermented vegetable and sweat aromas, but less intense toffee, exotic fruit and acid milk aromas. The texture differences noted between the cheeses from milk produced on the two areas may come from differences in primary proteolysis, partly due to different amounts of plasmin and plasminogen in milk and in cheeses. The aroma differences were related to differences in volatile compounds. Some compounds had a microbial origin, while some others may have come from the pasture.

Fetal alcohol syndrome: Report of a case.

A boy born to a known alcoholic mother demonstrated the fetal alcohol syndrome. Although considerably postterm, he weighed less than 1.5 kg (3 lb) at birth and has failed to catch up at 2 1/2 years of age. In addition to continuing prenatal and postnatal growth and developmental deficits, he has many of the other stigmata described as characteristic of this syndrome. To this list have been added other findings from our case.