Autochthonous Lactobacillus paracasei subsp. paracasei strains isolated from Caciocavallo cheese: identification and in-vitro investigation on potential probiotic and functional properties

Background: In recent years consumers, due to the growing interest for functional foods, have put particularly attention on products enriched with probiotic lactic acid bacteria for their ability to give human benefit by their assumption. Microorganisms to be considered as probiotic should be able to survive to gastrointestinal juices and colonize the intestinal tract to provide benefits to human health. The aim of the study consisted of the in vitro investigation of novel LAB strains, isolated during cheesemaking and ripening of Caciocavallo cheese, and on their probiotic potential for food application. Methods: In order to select potential probiotic bacteria, LAB isolates were preliminarily screened for their survival to simulated gastro-intestinal transitand assayed for other activities of probiotic and functional interest. Thanks to promising attitude as potential probiotics, four strains were tested to evaluate their adhesion ability on Caco-2 cell lines used as intestinal cell model. Microbiological data were analysed by one-way analysis of variance (ANOVA). Comparisons of means were carried out using post-hoc Tukey’s test. For vitro adhesion experiments, statistical significance was evaluated by Kruskal-Wallis test for equal medians. Results: Twenty-five LAB, presumptively identified as Lactobacillus spp., were isolated from cheese during 60 days of ripening and screened for their survival to simulated gastrointestinal transit. Sixteen isolates that showed a survival rate ≥85% were identifiedas 10 different profiles of Lb. paracasei subsp. paracasei. The 10 strains tolerated high concentration of bile salts by Minimal Inhibitory Concentration and growth rate assays and showed susceptibility or moderate susceptibility against antibiotics of human and veterinary importance, except for the resistanceto the class of aminoglycoside antibiotics. Eight out 10 strains showed in vitro cholesterol-lowering ability, whereas all strains showed antioxidant activity of their cell-free supernatants. Moreover, the four strains with highest survival to simulated gastrointestinal transit showed the ability to adhere to Caco-2 cells. Conclusion: The results suggest that some strains may be effective probiotics to be use as tool to design probiotic dairy products after confirmation probiotic activities in further in vivo studies. Findings of the present study suggest that four strains showed good or strong adherent ability on Caco-2 cell monolayer, that is one of prerequisite that probiotic bacteria must have to perform their functional properties. Keywords: adhesion, antioxidant activity, bile salts, cholesterol assimilation, dairy products, gastrointestinal resistance, probiotic lactobacilli.

The Effect of Field Heat Reduction Methods on Fresh and Processing Qualities of Red and Russet Potato Cultivars

The effect of three field heat reduction methods, including temperature lowering stepwise (TLS), temperature lowering gradually (TLG), and temperature lowering immediately (TLI), after harvesting on the quality of Russet Norkotah 3 and red skin numbered line CO 07102-1R potatoes were investigated. The tubers were analyzed at harvest (0 time), when they reached 3 °C, and after 6 months of storage at 3 °C for physiological weight loss, firmness, wound healing, total phenolics content, reducing sugars, and color of french fries. The results indicated that weight and firmness losses were lower under the TLS reduction method after 6 months of storage than TLG and TLI methods. The weight loss in TLS is 12%, TLG 14% and TLI 17% in CO 07102-1R whereas Russet Norkotah TLS is 4%, TLG 6%, and TLI 8% respectively. Wound healing was more effective using the TLS reduction method, especially in Russet Norkotah 3. French fry color was lighter at harvest (USDA grade 0), while there were no differences in the color of French fries prepared from tubers stored under the TLS and TLG methods (both had USDA grade 2). French fries were darker for tubers from the TLI method (USDA grade 4). The total phenolic content and reducing sugars were significantly increased in the TLI field heat reduction method. Keywords: Potato, Storage management, Wound healing, Weight loss, French fry

Studying the Influence of Storage Conditions, 1-MCP, and Packaging Films on Quality of Sweet Dalilah Green and Red Stage Peppers (Capsicum annuum L.)

Peppers are a popular fresh market commodity but have a limited shelf life. The present study evaluated the effects of storage time, packaging films, and 1-methylcyclopropene (1-MCP) on weight loss, firmness, respiration rate, ethylene production, ascorbic acid, antioxidant activity, and bioactive compounds of Sweet Delilah (Capsicum annuum). Four packaging films were tested in this study: polypropylene (P12F), laminated polynylon (30 NV), coextruded vacuum pouch (30 NVC), and polyethylene (P15G). Collectively, packaged peppers showed less weight loss than the control. When stored at the red stage, the firmness loss was 13 % in peppers that were treated with 1-MCP compared to 25% loss in the control samples. The most significant reduction in respiration rate in the red stage peppers was 0.88 ml kg-1 h-1 when packaged with 30NVC and 0.91 ml kg-1 h-1 when packaged with P15G, compared to 1.22 ml kg-1 h-1 for the control. The ranges of total phenolic and total flavonoid compounds were 3782 and 5090, respectively, in the green stage and 519 and 647 µg/g, respectively, in the green and red stages. When Sweet Delilah peppers that were treated with 1-MCP maintained higher levels of phenolic and flavonoid compounds than the control samples. Overall, the largest phenolic and flavonoid losses occurred from the control samples, while the smallest phenolic and flavonoid losses occurred from the packaged peppers. The highest ABTS activity was 150 µmol TE/g when packaged with P12G film, whereas the lowest ABTS activity was 143 µmol TE/g in the control samples in the red stage. Peppers packaged with 30NVC films retained higher ascorbic acid levels than peppers that were packaged with other films and the control samples. Keywords: Peppers, Phenolics, Flavonoids, Ascorbic acid, Antioxidant activity, Packaging.

Milk Cereal Drink Feeding Practices: A Descriptive Study Among Swedish Cohort of the IDEFICS Family Study

Background: Childhood overweight is an increasing public health concern and has recently been associated with the consumption of a traditional Swedish milk cereal drink (MCD). This study aimed to describe the consumption pattern of MCD among study participants in relation to the recommendations by the National Food Agency of Sweden. Method: A cross-sectional study among the Swedish cohort of the IDEFICS.Family (I.Family) study was conducted in 2013/2014. Swedish participants completed a questionnaire aimed at understanding the prevalence of consumption, timing, frequency, feeding modality and rationale for offering MCD. Results: Most children (74.7%) reportedly consumed MCD. Of those who consumed MCD, a large part of the participants consumed MCD two or more times a day with a high proportion of participants (87%) stating a preference for bottle-feeding. Keywords: Milk cereal drink, Obesity, Complementary food, Feeding practice, I. Family Study, Sweden.

Yeast α-L-Rhamnosidase: Sources, Properties, and Industrial Applications

Yeasts have been used for the heterologous production of a range of enzymes. However, α-L-rhamnosidase production in yeasts as well as its vast potential for biotechnological processes is less reported. α-L-Rhamnosidase is one of the important biotechnologically attractive enzymes in several industrial and biotechnological processes. In food and agriculture industries, the enzyme catalyzes the hydrolysis of hesperidin to release L-rhamnose and hesperidin glucoside, industrial removal of bitterness from citrus juices caused by naringin, and enhancing aroma in grape juices and derived beverages. In pharmaceutical and chemical industries, this enzyme is used in the structural determination of polysaccharides, glycosides and glycolipids, metabolism of gellan, conversion of chloropolysporin B to chloropolysporin C, and production of prunin. Rhamnosidases are extensively distributed in fungi and bacteria while their production from yeast sources is less reported. Yeast rhamnosidase is very important as it is produced in short-duration fermentation, with enhanced shelf life, high thermal stability, capable of retaining juice flavor, and is non-toxic for human consumption. In this review, an attempt has been made to fill up this gap by focusing on production, purification, characterization, structural and molecular biological studies of yeast rhamnosidase and its potential biotechnological applications. Keywords: Industrial applications, Naringin, Rhamnosidase, Yeast

Quorum sensing inhibitory effects of vanillin on the biofilm formation of Pseudomonas fluorescens P07 by transcriptome analysis

Pseudomonas fluorescens is an important psychrotrophic food-spoilage bacterium. Quorum sensing (QS) enables bacteria to control various physiological processes. Hence, targeting bacterial QS would be a novel method to improve food quality. In this study, P. fluorescens P07 was treated with vanillin, which showed strong QS inhibitory activity, and its resultant effects on swarming motility, biofilm formation, and extracellular polymeric substance (EPS) secretion were measured. The mechanisms underlying the inhibitory effects were then explored by transcriptomic analysis. The results showed that vanillin had inhibitory effects on swarming motility, biofilm formation, N-acyl-L-homoserine Lactone (AHLs) and EPS secretion of P. fluorescens P07. The result of transcriptionomic tests indicated that the decrease in bacterial biofilm formation was probably due to the influence of vanillin on mobility, adhesion, chemotaxis, EPS secretion, and QS system of the bacteria. Keywords: Pseudomonas fluorescens, quorum sensing, biofilm formation, transcriptome analysis, swarming motility

Effects of Organic Selenium on Laying Performance, Selenium Absorption and Utilization, Antioxidant Activity and Immunity in Laying Hens

To study on influences of organic selenium on laying performance, Se absorption and utilization, immunity and antioxidant activity, 400（laying rates 85%）hens during the period of 43-week were randomly allocated to 1 of 4 homogeneous treatments： (control treatment，no added Se feed; Na selenite, 0.3 mg Se/kg; yeast selenium, 0.3 mg Se/kg and DL-methionine selenium 0.3 mg Se/kg). Every treatment had 10 replicates, every replicate had 5 hencoops and every hencoop had 2 hens. We hypothesized that organic selenium was better than inorganic selenium, and DL-selenium had advantages over them of yeast selenium in some ways for laying hens. The experiment lasted for 77 d, with the first 7 d for adaptation. Egg production, laying rates and dry matter intake were recorded every day. And Se contents of serum, whole eggs, heart and liver, blood antioxidant and immunity index were analyzed in the 78th d of the study. The results showed Se sources had no significant effects on laying performance and eggs qualities （ P ＞ 0.05 ）, except for the groups of organic selenium increased egg mass or had trends of increasing laying rates compared with the groups of control and inorganic selenium in the tenth week significantly respectively（P﹤0.05 or P=0.07, P=0.06 and P=0.08）. The groups of organic selenium had increased the contents of Se in serum, whole eggs, heart and liver very significantly（P﹤0.01）；and increased glutathione peroxidase activity and antioxidant capacity significantly（P﹤0.05）. At same time, the groups of organic selenium had increased significantly or had trends to increase the immunoglobulin G in serum（P ﹤0.05 or P=0.05）. In a word, adding organic selenium in diets could improve laying performance, strengthen Se absorption and utilizations, antioxidant capacity and immunity of laying hens to the extent in a longer experiment. And the effects of DL-selenium had advantages over them of yeast selenium in some ways. It implicated that DL-selenium was benefited to production of laying hens and selenium-enriched eggs. Key words： Selenium；Laying performance; Absorption and utilization；Antioxidant activity; Immunity Summary text: Selenium is an essential mineral not only for animal nutrition, but also for humans’ nutrition. Organic selenium had more advantages in improvement of laying performance, Se absorption and utilizations, antioxidant capacity and immunity of laying hens. Especially, DL-selenium was a valuable product, which was benefits to improve production of laying hens and develop functional food, selenium-enriched eggs.

Cloning and Purification of Ornithine Transcarbamoylase from Lactobacillus brevis and Its Application on Regulating Ethyl Carbamate Formation in Chinese rice wine

It was studied that ornithine transcarbamoylase played important roles in ethyl carbamate (EC) formation. Ornithine transcarbamoylase (OTCase) can degrade citrulline, a precursor of EC, through arginine deiminase pathway. Therefore, they are generally added to regulate EC catabolism in rice wine fermentation. In this work, OTCase were added in different concentration and ferment time. It turned out addition of OTCase could reduce EC to some extent, especially for low concentration enzyme addition and mid-stage addition time. Furthermore, the production of amino acids, volatile flavor compounds and sense of taste were not markedly affected. The discoveries reveal that EC can be reduced by supplying OTCase while rice wine leavening. Key words: Ethyl carbamate, Ornithine transcarbamoylase, Rice wine fermentation, Enzyme inhibition