Fish proteins as targets of ferrous-catalyzed oxidation: identification of protein carbonyls by fluorescent labeling on two-dimensional gels and MALDI-TOF/TOF mass spectrometry

Protein oxidation in fish meat is considered to affect negatively the muscle texture. An important source of free radicals taking part in this process is Fenton's reaction dependent on ferrous ions present in the tissue. The aim of this study was to investigate the susceptibility of cod muscle proteins in sarcoplasmic and myofibril fractions to in vitro metal-catalyzed oxidation and to point out protein candidates that might play a major role in the deterioration of fish quality. Extracted control proteins and proteins subjected to free radicals generated by Fe(II)/ascorbate mixture were labeled with fluorescein-5-thiosemicarbazide (FTSC) to tag carbonyl groups and separated by two-dimensional gel electrophoresis. Consecutive visualization of protein carbonyl levels by capturing the FTSC signal and total protein levels by capturing the SyproRuby staining signal allowed us to quantify the relative change in protein carbonyl levels corrected for changes in protein content. Proteins were identified using MALDI-TOF/TOF mass spectrometry and homology-based searches. The results show that freshly extracted cod muscle proteins exhibit a detectable carbonylation background and that the incubation with Fe(II)/ascorbate triggers a further oxidation of both sarcoplasmic and myofibril proteins. Different proteins exhibited various degrees of sensitivity to oxidation processes. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), nucleoside diphosphate kinase B (NDK), triosephosphate isomerase, phosphoglycerate mutase, lactate dehydrogenase, creatine kinase, and enolase were the sarcoplasmic proteins most vulnerable to ferrous-catalyzed oxidation. Moreover, NDK, phosphoglycerate mutase, and GAPDH were identified in several spots differing by their pI, and those forms showed different susceptibilities to metal-catalyzed oxidation, indicating that post-translational modifications may change the resistance of proteins to oxidative damage. The Fe(II)/ascorbate treatment significantly increased carbonylation of important structural proteins in fish muscle, mainly actin and myosin, and degradation products of those proteins were observed, some of them exhibiting increased carbonylation levels.     

Distribution of Cd, Ni, Cr, and Pb in Amended Soils from Alicante Province (SE, Spain)

Heavy metals can be transferred from soils to other ecosystem parts and affect ecosystems and human health through the food chain. Today the use of biosolids to improve the nutrient contents of a soil is a common practice. Contamination of soils by potentially toxic elements (e.g., Cd, Ni, Cr, Pb) from amendments of biosolids is subject to strict controls within the European Community in relation to total permissible metal concentrations, soil properties and intended use. In this context, heavy metal concentrations were studied in agricultural soils devoted to vegetable crops in the province of Alicante (SE Spain), where an intensive agriculture takes place. This study is aimed at ascertaining the chemical partitioning of Cd, Ni, Cr, and Pb in agricultural soils repeatedly amended with sludge. Selected soil properties relevant to control the mobility and bioavaibility of heavy metals were analyzed for the general characterisation of these agricultural soils. The distribution of chemical forms of Cd, Ni, Cr, and Pb in five biosolids-amended soils was studied using a sequential extraction procedure that fractionates the metal into soluble-exchangeable, specifically sorbed-carbonate bound, oxidizable, reducible, and residual forms. The biosolids incorporation has modified the soil composition, leading to the increment of heavy metals. The residual, reducible, and carbonate-sorbed forms were dominant. Detailed knowledge of the soil at the application site, especially pH, CEC, buffering capacity, organic matter, clay minerals, and clay content, is essential.     

Separation and HPLC-MS identification of phenolic antioxidants from agricultural residues: almond hulls and grape pomace

Almond hulls and grape pomace are residues abundantly generated by agricultural industries, which could be processed to obtain bioactive products. To this purpose, crude ethanol extracts from both agricultural byproducts were attained and subsequently fractionated in order to obtain an organic/water fraction (FOW). Extracts and fractions were analyzed for antioxidant power and their phenolic components tentatively identified by HPLC-MS. Chromatographic peaks of almond hull extracts showed the occurrence of hydroxybenzoic and cinnamic acid derivatives, with minor presence of flavan-3-ols (ECG, EGCG), whereas the FOW fraction offered the additional presence of epicatechin (EC) and glycosylated flavonols. In the composition for extracts of white and red grape pomace several of these compounds were also detected but basically consisted of glycosylated flavonols (quercetin, kaempferol). As a difference between both grape pomaces, myricetin glycosyde was found in that from the red variety, whereas flavan-3-ols (EC, afzelechin) were only identified in white pomace. When their FOW fractions were analyzed, gallic acid and some hydroxybenzoic acids were additionally detected. Antioxidant activity was assessed by DPPH and TBARS assays. Almond hulls showed inhibition percentages lower than 50% in both assays, while the inhibition percentage ranged from 80% to 90% in pomace extracts. Red grape pomace extract was the most efficient antioxidant, with an EC50 value of 0.91 g/L for TBARS and 0.20 g/L for DPPH. Even appearing as two quite different vegetal matrixes, the composition of phenolics in grape pomace and almond hulls is quite similar, the main difference being the major occurrence of flavonols in grape pomace. This fact could presumably explain the lower antiradical activity of hull extracts.     

New Saccharomyces cerevisiae baker's yeast displaying enhanced resistance to freezing

Three procedures were used to obtain new Saccharomyces cerevisiae baker's yeasts with increased storage stability at -20, 4, 22, and 30 degrees C. The first used mitochondria from highly ethanol-tolerant wine yeast, which were transferred to baker's strains. Viability of the heteroplasmons was improved shortly after freezing. However, after prolonged storage, viability dramatically decreased and was accompanied by an increase in the frequency of respiratory-deficient (petite) mutant formation. This indicated that mitochondria were not stable and were incompatible with the nucleus. The strains tested regained their original resistance to freezing after recovering their own mitochondria. The second procedure used hybrid formation after protoplast fusion and isolation on selective media of fusants from baker's yeast meiotic products resistant to parafluorphenylalanine and cycloheximide, respectively. No hybrids were obtained when using the parentals, probably due to the high ploidy of the baker's strains. Hybrids obtained from nonisogenic strains manifested in all cases a resistance to freezing intermediate between those of their parental strains. Hybrids from crosses between meiotic products of the same strain were always more sensitive than their parentals. The third method was used to develop baker's yeast mutants resistant to 2-deoxy-d-glucose (DOG) and deregulated for maltose and sucrose metabolism. Mutant DOG21 displayed a slight increase in trehalose content and viability both in frozen doughs and during storage at 4 and 22 degrees C. This mutant also displayed a capacity to ferment, under laboratory conditions, both lean and sweet fresh and frozen doughs. For industrial uses, fermented lean and sweet bakery products, both from fresh and frozen doughs obtained with mutant DOG21, were of better quality with regard to volume, texture, and organoleptic properties than those produced by the wild type.     

Mapping vineyard vigor using airborne remote sensing: relations with yield,berry composition and sanitary status under humid climate conditions

Precision Agriculture - The aim of this study was to assess the spatial variability of plant vigor in a vineyard in a humid climate. Normalised Difference Vegetation Index (NDVI) was used for...     

Spray and economics assessment of a UAV-based ultra-low-volume application in olive and citrus orchards

Precision Agriculture - Automation is a new frontier in specialty agriculture equipment. Specifically, unmanned aerial vehicles (UAV), machine vision and robotics will increasingly appear in...     

Ripe Banana Flour as a Source of Antioxidants in Layer and Sponge Cakes

About one-fifth of all bananas harvested become culls that are normally disposed of improperly. However, ripe banana pulp contains significant amounts of fibre and polyphenol compounds as well as a high content of simple sugars (61.06 g/100 g), making it suitable for sucrose replacement in bakery products. This work studied the feasibility of incorporating ripe banana flour (20 and 40% of replacement) in cake formulation. Physical, nutritional and sensory attributes of sponge and layer cakes were evaluated. The inclusion of ripe banana flour generally led to an increased batter consistency that hindered cake expansion, resulting in a slightly lower specific volume and higher hardness. This effect was minimised in layer cakes where differences in volume were only evident with the higher level of replacement. The lower volume and higher hardness contributed to the decline of the acceptability observed in the sensory test. Unlike physical attributes, the banana flour inclusion significantly improved the nutritional properties of the cakes, bringing about an enhancement in dietary fibre, polyphenols and antioxidant capacity (up to a three-fold improvement in antioxidant capacity performance). Therefore, results showed that sugar replacement by ripe banana flour enhanced the nutritional properties of cakes, but attention should be paid to its inclusion level.     

Nutritional Composition,Bioactive Compounds and Antioxidant Activity of Wild Edible Flowers Consumed in Semiarid Regions of Mexico

Plant Foods for Human Nutrition - In semiarid regions of Mexico, it is common to use the floristic richness of wild plants as food ingredients. Hence, flowers of Agave salmiana, Aloe vera,...     

Effect of Ultrasound on In Vitro Bioaccessibility of Phenolic Compounds and Antioxidant Capacity of Blackberry (Rubus fruticosus) Residues cv. Tupy

Plant Foods for Human Nutrition - Agro-industries residues of fruit are a source of antioxidant compounds with a possible health impact. The aim of this study was to evaluate the total phenolic...