Extracts of Mexican Oregano (<Emphasis Type="Italic">Lippia berlandieri</Emphasis> Schauer) with Antioxidant and Antimicrobial Activity

Antimicrobial activity of fractions obtained from Mexican oregano (Lippia berlandieri Schauer) chloroform extract was tested by growth inhibition against Escherichia coli, Staphylococcus aureus and Bacillus cereus, and antioxidant capacity was tested by inhibition of linoleic acid oxidation. Fractions were obtained by differences in polarity or structure (phenolic and non-phenolic fraction). Gram-positive organisms were more susceptible to Mexican oregano extracts. Fraction 3 (by polarity) and phenolic fractions I, II, III, IV and V were the extracts with higher antimicrobial activity. The non-phenolic fraction had effect against B. cereus. Polarity fraction 5 and phenolic Fraction II had a high antioxidant capacity; a 0.08% concentration of fraction 5 had a similar effect as butylated hydroxytoluene at 0.01% concentration. Fractions of Mexican oregano with different polarity and functional groups had antioxidant and antimicrobial activity and can be used in a variety of applications.     

Use of waste materials for Lactococcus lactis development

BACKGROUND: Lactococcus lactis is an interesting microorganism with several industrial applications, particularly in the food industry. As well as being a probiotic species, L. lactis produces several metabolites with interesting properties, such as lactic acid (LA) and biosurfactants. Nevertheless, L. lactis is an especially demanding species since it has strong nutritional requirements, implying the use of complex and expensive culture media. RESULTS: The results showed the potential of L. lactis CECT‐4434 as a LA and biosurfactant producer. The economical cost of L. lactis cultures can be reduced by replacing the MRS medium by the use of two waste materials: trimming vine shoots as C source, and 20 g L^?1 distilled wine lees (vinasses) as N, P and micronutrient sources. From the hemicellulosic fraction, 14.3 g L^?1 LA and 1.7 mg L^?1 surfactin equivalent were achieved after 74 h (surface tension reduction of 14.4 mN m^?1); meanwhile, a simultaneous saccharification and fermentation process allowed the generation of 10.8 g L^?1 LA and 1.5 mg L^?1 surfactin equivalent after 72 h, reducing the surface tension by 12.1 units at the end of fermentation. CONCLUSIONS: Trimming vine shoots and vinasses can be used as alternative economical media for LA and cell‐bound biosurfactant production. Copyright © 2010 Society of Chemical Industry     

Survival analysis methodology to predict the shelf-life of probiotic flavored yogurt

The feasibility of survival analysis methodology was used to determine the shelf-life of probiotic strawberry flavored yogurt supplemented with Bifidobacteirum animalis DN 173010 W was investigated. The quality parameters of probiotic yogurts were related to storage conditions which they are submitted. The consumers were shown sensitive to changes towards sensory characteristics introduced into the products. Using the survival analysis and considering 25% and 50% probability of consumer rejection, the shelf-life of the probiotic yogurt was estimated at 38 and 53 days, respectively. The findings of this research highlighted the feasibility this technique to determine the shelf-life of foods, in particular, functional foods, as probiotic yogurts.     

Effect of fermentation temperature on microbial population evolution using culture-independent and dependent techniques

The population dynamics of micro-organisms during grape-must fermentation has been thoroughly studied. However, the main approach has relied on microbiological methods based on plating. This approach may overlook micro-organisms that (i) grow slowly or do not grow well on artificial media or (ii) whose population size is small enough to be detected by regular sampling. Culture-independent methods have been used and compared with the traditional plating method during wine fermentations performed at two different temperatures (13 °C and 25 °C). These methods include a qualitative technique, the DGGE; a semi-quantitative technique, the direct cloning of amplified DNA; and a quantitative technique, the QPCR. The biodiversity observed in the must and at the beginning of fermentation was much higher when DGGE or direct cloning were used. Quantification of the most frequent non-Saccharomyces yeast, Hanseniaspora uvarum and Candida zemplinina, showed that they survived throughout the fermentation process and, specifically, it revealed the quantitatively relevant presence of C. zemplinina until the end of fermentation.     

Uptake of Tritiated Liquids by Individual Breakfast Cereal Flakes

ABSTRACT: Surface liquid adhesion (SLA) and liquid absorption (LA) of tritiated liquids, including water and skim, low-fat, whole, and fat-enriched milks, by cornflakes (CF) and frosted flakes (FF) were determined by scintillation counting using water-[³H] at 0.5 μCi/mL. SLA or the liquid adhering to individual flakes after a short immersion period was the same for CF and FF in the case of water (approximately 0.011 μL mm⁻² of flake) but were always higher for CF than for FF and increased as the fat content in milks augmented. LA of individual flakes, followed for 300 s of soaking, increased with time and was always higher for CF than for FF (for the same liquid), however, data did not follow a regular pattern. Flakes showed quite compact outer surfaces and an internal porous matrix composed of air cells of various sizes separated by dense walls of different thicknesses. This heterogeneous microstructure of individual flakes may be the cause of the lack of a simple kinetics during the soaking process. Previous results obtained by soaking a mass of flakes overestimated the uptake of fluid by individual because they included the liquid occluded between the flakes.     

Influence of Homogenization Conditions on Physical Properties and Antioxidant Activity of Fully Biodegradable Pea Protein–Alpha-Tocopherol Films

In this study, antioxidant biodegradable films based on pea protein and alpha-tocopherol were successfully developed by solution casting. The effect of both the homogenization conditions (rotor–stator and microfluidizer) and the relative humidity (RH) on the microstructure and physical properties (transparency, tensile, oxygen and water vapour barrier properties) of pea protein/alpha-tocopherol-based films was evaluated. The addition of alpha-tocopherol produced minimal changes in the films’ transparency, while providing them with antioxidant properties and improved water vapour and oxygen barrier properties (up to 30 % in both water vapour and oxygen permeability) when films were at low and intermediate RH. The addition of alpha-tocopherol in microfluidized films gave rise to an increase in their resistance to break and extensibility (up to 27 % in E values) at intermediate and high RH. These results add a new insight into the potential of employing pea protein and alpha-tocopherol in the development of fully biodegradable antioxidant films which are of interest in food packaging.     

Determination of a representative volume element based on the variability of mechanical properties with sample size in bread

Quantitative analysis of food structure is commonly obtained by image analysis of a small portion of the material that may not be the representative of the whole sample. In order to quantify structural parameters (air cells) of 2 types of bread (bread and bagel) the concept of representative volume element (RVE) was employed. The RVE for bread, bagel, and gelatin-gel (used as control) was obtained from the relationship between sample size and the coefficient of variation, calculated from the apparent Young's modulus measured on 25 replicates. The RVE was obtained when the coefficient of variation for different sample sizes converged to a constant value. In the 2 types of bread tested, the tendency of the coefficient of variation was to decrease as the sample size increased, while in the homogeneous gelatin-gel, it remained always constant around 2.3% to 2.4%. The RVE resulted to be cubes with sides of 45 mm for bread, 20 mm for bagels, and 10 mm for gelatin-gel (smallest sample tested). The quantitative image analysis as well as visual observation demonstrated that bread presented the largest dispersion of air-cell sizes. Moreover, both the ratio of maximum air-cell area/image area and maximum air-cell height/image height were greater for bread (values of 0.05 and 0.30, respectively) than for bagels (0.03 and 0.20, respectively). Therefore, the size and the size variation of air cells present in the structure determined the size of the RVE. It was concluded that RVE is highly dependent on the heterogeneity of the structure of the types of baked products.     

The Color of Olive Oils: The Pigments and Their Likely Health Benefits and Visual and Instrumental Methods of Analysis

ABSTRACT: The color of olive oils, and of foods in general, can influence consumer choices to a large extent and can be related to the processing treatments they have undergone. Olive oil color is due to 2 types of pigments, chlorophylls and carotenoids, which are attracting the attention of the scientific community due to the probable health benefits they can provide. Appropriate methodologies for the meaningful definition of the color of olive oil are therefore necessary for various reasons. In this review, we discuss the importance of olive oil color and the applicable legislation and regulation, including sections devoted to the pigments accounting for the growing importance as likely health‐promoting substances. Furthermore, we review in depth the different approaches (visual and instrumental methods) used for color measurements in the last 50 y. Instrumental methods have been shown to be highly appropriate for objective assessments and also for the rapid determination of the pigments.     

A dimensional reduction approach to modulate the core ruminal microbiome associated with methane emissions via selective breeding

The rumen is a complex microbial system of substantial importance in terms of greenhouse gas emissions and feed efficiency. This study proposes combining metagenomic and host genomic data for selective breeding of the cow hologenome toward reduced methane emissions. We analyzed nanopore long reads from the rumen metagenome of 437 Holstein cows from 14 commercial herds in 4 northern regions in Spain. After filtering, data were treated as compositional. The large complexity of the rumen microbiota was aggregated, through principal component analysis (PCA), into few principal components (PC) that were used as proxies of the core metagenome. The PCA allowed us to condense the huge and fuzzy taxonomical and functional information from the metagenome into a few PC. Bivariate animal models were applied using these PC and methane production as phenotypes. The variability condensed in these PC is controlled by the cow genome, with heritability estimates for the first PC of ~0.30 at all taxonomic levels, with a large probability (>83%) of the posterior distribution being >0.20 and with the 95% highest posterior density interval (95%HPD) not containing zero. Most genetic correlation estimates between PC1 and methane were large (≥0.70), with most of the posterior distribution (>82%) being >0.50 and with its 95%HPD not containing zero. Enteric methane production was positively associated with relative abundance of eukaryotes (protozoa and fungi) through the first component of the PCA at phylum, class, order, family, and genus. Nanopore long reads allowed the characterization of the core rumen metagenome using whole-metagenome sequencing, and the purposed aggregated variables could be used in animal breeding programs to reduce methane emissions in future generations.