Iron deficiency enhances bioactive phenolics in lemon juice

BACKGROUND This study was designed to describe the phenolic status of lemon juice obtained from fruits of lemon trees differing in iron (Fe) nutritional status. Three types of Fe(III) compound were used in the experiment, namely a synthetic chelate and two complexes derived from natural polymers of humic and lignine nature. RESULTS All three Fe(III) compounds were able to improve the Fe nutritional status of lemon trees, though to different degrees. This Fe(III) compound effect led to changes in the polyphenol content of lemon juice. Total phenolics were decreased (～33% average decrease) and, in particular, flavanones, flavones and flavonols were affected similarly. CONCLUSION Iron‐deficient trees showed higher phenolic contents than Fe(III) compound‐treated trees, though Fe deficiency had negative effects on the yield and visual quality of fruits. However, from a human nutritional point of view and owing to the health‐beneficial properties of their bioavailable phenolic compounds, the nutritional quality of fruits of Fe‐deficient lemon trees in terms of phenolics was higher than that of fruits of Fe(III) compound‐treated lemon trees. Moreover, diosmetin‐6,8‐di‐C‐glucoside in lemon juice can be used as a marker for correction of Fe deficiency in lemon trees. Copyright © 2011 Society of Chemical Industry     

The occurrence of fungi, yeasts and bacteria in the air of a Spanish winery during vintage

This research studies the presence of microorganisms of enological interest (yeasts, bacteria and molds) and their evolution in the air of a wine cellar. The samples were taken throughout the winemaking campaign (September-December) in a winery of the D.O.Ca. Rioja, Spain. They were collected using an airIDEAL atmosphere sampler from Biomerieux. For the isolation, specific selective media were used for each group of microorganisms. The results obtained indicate that the presence in the winery air of the various different microorganisms studied is directly related to the winemaking processes that are taking place in the winery. Thus, the number of molds present decreases once grapes have ceased to be brought into the winery. The maximum number of yeasts in the air is found when all the vats in the cellar are fermenting, while the lactic bacteria are not detected until the first malolactic fermentation begins. The species of yeasts and molds identified are also related to the winemaking processes. The coincidence of strains of Saccharomyces cerevisiae among those present in the vats during alcoholic fermentation and those isolated from the air, confirms the role of the latter as a transmitter of microorganisms.     

Assessment of production efficiency,physicochemical properties and storage stability of spray‐dried chlorophyllide,a natural food colourant,using gum Arabic,maltodextrin and soy protein isolate‐based carrier systems

The aim of this research was to study spray drying as potential action to protect chlorophyllide from environmental conditions for shelf‐life extension and characterisation of the powders. Six formulations were prepared with 7.5 and 10 g of carrier agents [gum Arabic (GA), maltodextrin (MA) and soybean protein isolate (SPI)]/100 mL of chlorophyllide solutions. The powders were evaluated for morphological characteristics (SEM), particle size, water activity, moisture, density, hygroscopicity, cold water solubility, sorption isotherms, colour and stability, during 90 days. All the powders were highly soluble, with solubility values around 97%. A significant lower hygroscopicity was observed for GA powders, whilst the lower X_m values obtained by GAB equation fitting of the sorption isotherms was observed for the 7.5 g MA/100 mL samples. All formulations, but the 1 (7.5 g SPI/100 mL of chlorophyllide), provided excellent stability to the chlorophyllide during 90 days of storage even at room temperature.     

Malolactic fermentation of Tempranillo wine: contribution of the lactic acid bacteria inoculation to sensory quality and chemical composition

Malolactic fermentation (MLF) of Tempranillo Rioja wines (Spain) inoculated with two lactic acid bacteria (LAB) strains were studied and compared with spontaneous MLF. Inoculation with selected Oenococcus oeni lyophila shortened MLF duration up to 19 days and lead to wines with more fresh and fruity characters, especially when implantation was 100%. We demonstrated modifications in the concentration of volatile and nitrogenous compounds and a good correlation between analytical and sensory attributes was also noted. In addition, the low initial amino acid concentration and the consumption of these compounds by the inoculated yeast strain during alcoholic fermentation resulted in wines with very low biogenic amines levels (under 3.75 mg L^?1) after MLF and 3 month storage period in all cases. The results showed the significance of choose the most suitable starter to elaborate quality wines and suggest the control of amino acid content in must and wine to prevent the formation of biogenic amines.     

Biochemical characterisation of MX-4, a plant cysteine protease of broad specificity and high stability

A new proteinase, mexicain-IV (MX-4), has been purified to homogeneity from the latex fruits of Jacaratia mexicana (formely Pileus mexicanus), a plant member of the Caricaceae family. MX-4 shows a Mr of 23.7 kDa, pI of 9.3 and maximum proteolytic activity on casein and BAPNA at pH 8.0–8.5 and pH 7.0–7.5, respectively. The amino acid sequence of MX-4 and its reversible inhibition by HgCl₂ show that the proteinase belongs to the family of cysteine proteinases. This enzyme exhibits rather broad substrate specificity, although there seems to be a slight preference for cleavage of peptides having certain hydrophobic residues in the P2 position. Biochemical and circular dichroism studies revealed that this enzyme belongs to the α + β class of proteins, in agreement with the results obtained by X-ray crystallographic structure determination, and showed that MX-4 has a higher pH and thermal stability than other members of the Caricaceae family, including papain. These properties make this novel protease a suitable novel analytical tool for the proteomic analysis of peptide fragments of great potential interest in the food industry and other industries.     

Survival and growth of Listeria monocytogenes and enterohemorrhagic Escherichia coli O157:H7 in minimally processed artichokes

The ability of Listeria monocytogenes and Escherichia coli O157:H7 inoculated by immersion (at 4.6 and 5.5 log CFU/ g, respectively) to survive on artichokes during various stages of preparation was determined. Peeling, cutting, and disinfecting operations (immersion in 50 ppm of a free chlorine solution at 4 degrees C for 5 min) reduced populations of L. monocytogenes and E. coli O157:H7 by only 1.6 and 0.8 log units, respectively. An organic acid rinse (0.02% citric acid and 0.2% ascorbic acid) was more effective than a tap water rinse in removing these pathogens. Given the possibility of both pathogens being present on artichokes at the packaging stage, their behavior during the storage of minimally processed artichokes was investigated. For this purpose, batches of artichokes inoculated with L. monocytogenes or E. coli O157:H7 (at 5.5 and 5.2 log CFU/g, respectively) were packaged in P-Plus film bags and stored at 4 degrees C for 16 days. During this period, the equilibrium atmosphere composition and natural background microflora (mesophiles, psychrotrophs, anaerobes, and fecal coliforms) were also analyzed. For the two studied pathogens, the inoculum did not have any effect on the final atmospheric composition (10% O2, 13% CO2) or on the survival of the natural background microflora of the artichokes. L. monocytogenes was able to survive during the entire storage period in the inoculated batches, while the E. coli O157:H7 level increased by 1.5 log units in the inoculated batch during the storage period. The modified atmosphere was unable to control the behavior of either pathogen.     

Adhesion and aggregation properties of probiotic and pathogen strains

Autoaggregation has been correlated with adhesion, which is known to be a prerequisite for colonization and infection of the gastrointestinal tract by many pathogens. The coaggregation properties of probiotic strains with pathogens as well as their ability to displace pathogens are of importance for therapeutic manipulation of the aberrant intestinal microbiota. Consequently, the ability to aggregate and coaggregate are desirable properties for probiotics in health-promoting foods. Aggregation assays and bacterial adhesion to hydrocarbons (BATH test) demonstrated significant differences in cell surface properties among the tested commercial probiotic strains. Hydrophobicity increased when the cells were heat-inactivated. All probiotic strains tested showed aggregation abilities with the pathogen strains tested, but the results were strain-specific and dependent on time and incubation conditions. Our results indicate that the ability to autoaggregate, together with cell-surface hydrophobicity and coaggregation abilities with pathogen strains can be used for preliminary screening in order to identify potentially probiotic bacteria suitable for human or animal use.     

Changes in biogenic amine and polyamine contents in slightly fermented sausages manufactured with and without sugar

The effect of sugar omission on biogenic amine contents of slightly fermented sausages during ripening and storage was evaluated. Two batches of spontaneously fermented sausages were produced with and without sugars in two different trials at pilot-plant scale. Ripened sausages were stored at 4 and 19°C for a further 20 days. Tyramine and cadaverine were the main amines formed during ripening, their contents being significantly higher in batches without sugar. High counts of LAB and Enterobacteriaceae could be associated with the production of tyramine and cadaverine, respectively. The occurrence of putrescine depended on the trial and batch. Sausages without sugar contained more putrescine than those with sugar in trial 1, but this was not repeated in trial 2, in which a high production of agmatine occurred. Tryptamine and phenylethylamine were only detected in the later stages of ripening, their contents also being higher in sausages without sugar. Biogenic amine contents generally rose during storage at 19°C, the increase being especially important for cadaverine and tyramine in sausages without sugar. Levels of spermidine and spermine remained constant during ripening and decreased slightly during storage. Sugar omission is not recommended because it might increase biogenic amine accumulation during the manufacture and storage of slightly fermented sausages.