Interaction of yeasts with the products resulting from the condensation reaction between (+)-catechin and acetaldehyde

The condensation reaction between (+)-catechin and acetaldehyde was studied in model solutions in the presence and absence yeasts in order to evaluate its contribution to color changes in fermented drinks such as white wine. On the basis of the results, the yeasts retain the oligomers produced in the reaction, their retention ability increasing for higher polymerization degrees. As a result, the color of model solutions, measured as the absorbance at 420 nm, was found to decrease after the addition of yeasts. On the other hand, the yeasts exhibited no inhibitory effect on the condensation reaction, which took place at the same rate in their presence and absence. At acidity levels and reactant concentrations similar to those in wine, with acetaldehyde in high concentration as it is present in sherry wines, the reaction was found to occur very slowly. Taking into account that Yeasts are present during most of the winemaking process; consequently, they retain oligomers, and the studied reaction could mainly contribute to the alteration of the color of white wine after bottling.     

Chemical Composition and Nutritional Value of Unripe Banana Flour (<Emphasis Type="Italic">Musa acuminata</Emphasis>, var. Nanicão)

Banana flour obtained from unripe banana (Musa acuminata, var. Nanicão) under specific drying conditions was evaluated regarding its chemical composition and nutritional value. Results are expressed in dry weight (dw). The unripe banana flour (UBF) presented a high amount of total dietary fiber (DF) (56.24 g/100 g), which consisted of resistant starch (RS) (48.99 g/100 g), fructans (0.05 g/100 g) and DF without RS or fructans (7.2 g/100 g). The contents of available starch (AS) (27.78 g/100 g) and soluble sugars (1.81 g/100 g) were low. The main phytosterols found were campesterol (4.1 mg/100 g), stigmasterol (2.5 mg/100 g) and β-sitosterol (6.2 mg/100 g). The total polyphenol content was 50.65 mg GAE/100 g. Antioxidant activity, by the FRAP and ORAC methods, was moderated, being 358.67 and 261.00 μmol of Trolox equivalent/100 g, respectively. The content of Zn, Ca and Fe and mineral dialyzability were low. The procedure used to obtain UBF resulted in the recovery of undamaged starch granules and in a low-energy product (597 kJ/100 g).     

Cytotoxic effect of potato aspartic proteases (StAPs) on Jurkat T cells

StAPs are potato aspartic proteases with cytotoxic activity against plant pathogens and spermatozoa. StAPs cytotoxic activity is selective, since these proteins do not exert toxic effect on plant cells and erythrocytes. In this work, we investigated the capacity of StAPs to exert cytotoxicity on human leukaemia cells. Obtained results show that StAPs induce apoptosis on Jurkat T cells after a short time of incubation in a dose-dependent manner. However, no significative effect on the T lymphocytes viability was observed at all StAPs incubation times and concentrations tested. These results suggest that StAPs can be conceptually promising leads for cancer therapy.     

On-farm evaluation of the effect of coffee pulp supplementation on milk yield and dry matter intake of dairy cows grazing tropical grasses in central Mexico

Tropical grasses are the primary nutrient resource for cattle production in the tropics, and they provide low-cost nutrients to cattle. However, its production is constrained by seasonal changes and quality; hence, appropriate usage of relatively inexpensive agricultural by-products is important to profitable livestock production. The objective of the study was to evaluate the effect of supplementing coffee pulp to dairy cows grazing tropical grasses on milk yield and forage intake. Four multiparous crossed Holstein–Brown Swiss–Zebu cows of similar weight and milk yield were used. The effect of 10%, 15% and 20% inclusion of coffee pulp in dairy concentrates on milk yield and forage intake was analysed using a 4 × 4 Latin square design. Results showed that there were no significant effects (P > 0.05) in grass dry matter intake, milk yield, milk composition body weight and body condition score due to the inclusion of coffee pulp in the dairy concentrates. It is concluded that coffee pulp can be included at levels of 20% in the concentrate without compromising significantly (P > 0.05) milk yield, milk composition and grass dry matter intake. It also was concluded that cost of concentrate is reduced in 20% by the inclusion of coffee pulp.     

Effects of ultra-high-pressure homogenization treatment on the lipolysis and lipid oxidation of milk during refrigerated storage

Free fatty acid (FFA) release and quantification and lipid oxidation extent of ultra-high-pressure homogenized (UHPH) milk samples were evaluated to assess the effect of UHPH on the susceptibility of milk lipids to lipolysis and oxidation. Milk was UHPH-treated at 200 and 300 MPa with inlet temperatures of 30 and 40 degrees C. UHPH-treated samples were compared to high-pasteurized milk (PA; 90 degrees C, 15 s). Results showed that all FFA increased significantly during storage only in 200 MPa samples. Lipid oxidation was measured as an accumulation of lipid hydroperoxides as the primary oxidation product and malondialdehyde and hexanal as the secondary oxidation products. Samples treated at 300 MPa presented higher malondialdehyde and hexanal content compared to 200 MPa treated-samples and to PA milk.     

Changes in color and phenolic compounds during the raisining of grape cv. Pedro Ximenez

Changes in color parameters and phenolic compounds during the sun-drying grape raisining of cv. Pedro Ximenez to obtain sweet wines are studied. Browning increases during the process as a result of the contribution to a greater extent of the low and medium molecular size polymers than the high molecular size polymers. Raisining decreases hue and lightness and increases chroma, all measured as CIELab parameters, indicating a color change to dark reddish hues that is also preferentially due to low and medium molecular size polymers. Most of the phenols studied increase in concentration during raisining, essentially through the concentration effect resulting from the loss of water in the grapes. The concentration changes, however, are comparatively small for hydroxycinnamic esters and flavan-3-ol derivatives, suggesting that these phenolic fractions undergo predominantly oxidative degradation reactions by enzymatic pathways, contributing strongly to the browning of grapes.     

Bacterial diversity and occurrence of ammonia-oxidizing bacteria in the Atacama Desert soil during a “desert bloom” event

The Atacama Desert, located in northern Chile, is one of the driest deserts on the Earth. However, in some years, short and sporadic rainfall in the southern end of this desert has increased the soil moisture that produces ephemeral “desert bloom”. Our goal was to assess the composition of the bacterial community and determine variations in the ammonia-oxidizing bacteria guild diversity from soils collected during the course of the “desert bloom” event. The bacterial composition from this arid soil was determined by cloning and sequencing the 16S rRNA gene. A relatively high diversity of clones belonging to 14 bacterial groups was detected. The ammonia-oxidizers showed a significantly higher diversity of amoA gene clones after the “desert bloom” than during or at the beginning of this event. All sequences obtained were related to Nitrosospira genera and environmental clones. These results suggest that the diversity of ammonia-oxidizing bacteria in this arid soil can be affected by the occurrence of “desert bloom”.     

Effect of Colletia hystrix (Clos), a pioneer actinorhizal plant from the Chilean matorral, on the genetic and potential metabolic diversity of the soil bacterial community

Colletia hystrix are dominant shrubs in the sclerophyllous matorral, a natural ecosystem in the central valley of Chile affected by erosion, soil with low fertility and limiting nitrogen. The soil microbial communities associated to these pioneer plants have received little attention even though they may have an important role in the ability of these to colonize the nutrient-poor soils from these semi-arid ecosystems. T-RFLP profiles using 16S rDNA were used to compare the bacterial community structure from soil samples (enriched and unenriched) associated to C. hystrix and neighboring soil without plant cover (bulk soil). Additionally, the microbial communities from both habitats were compared at the metabolic profile level using the Biolog EcoPlate™ system. Our results showed that the bacterial community from samples of soil associated to these plants formed a separate cluster from samples derived from the neighboring soil. These data suggest that soil associated to C. hystrix is a different microhabitat to bulk soil. When an enrichment step was performed on the samples, the T-RFLP profiles obtained showed few T-RFs suggesting that only some species were recovered. The enriched samples exhibited a low similarity between them and are clearly separated from the unenriched samples. On the other hand, the comparison of the unenriched samples from both habitats based on sole-carbon-source utilization profiles was unable to differentiate the samples according to their habitat.