Non-starch polysaccharide composition of two cultivars of banana (Musa acuminata L.: cvs Mysore and Nanicao)

Fruits represent a rich source of soluble and insoluble fibre, and the pectin is the most common and known soluble fraction from the cell wall solubilization occurring during fruit ripening. Banana fruit, for example, is one of the most consumed fruits in the world, but its non-starch polysaccharide composition is almost unknown. Despite few works have been carried out about the enzymes concerning cell wall loosening focusing banana ripening, there is no knowledge about the composition of the banana cell wall. Moreover, there is no information about the influence of the cultivar in that composition. Nanicao and Mysore cultivars were chosen for this work because of their differential accumulation of both starch during development and amounts of total fibre in the ripe fruit. Nanicao and Mysore had their fibres subfractioned and their composition analysed. Results showed that the cultivars are distinct not only in terms of starch and soluble sugars accumulation, but also in non-starch polysaccharides amounts and composition. Non-starch polysaccharides are similar in total amounts in both banana cultivars (similar to 3.5), but substantially different in the content of CDTA and NaOH-4M soluble fractions and also in the molecular mass distribution of WSP and CDTA. Nanicao has more calcium-linked pectin than Mysore, which in turn is richer in hemicellulose-like polysaccharides. Both cultivars likewise cereals polysaccharides seem to be composed of galacturonans and arabinoxylans.(c) 2007 Elsevier Ltd. All rights reserved.

Application of thermal sums concept to estimate the time to harvest new banana hybrids for export

Application of the thermal sum concept was developed to determine the optimal harvesting stage of new banana hybrids to be grown for export. It was tested on two triploid hybrid bananas, FlhorBan 916 (F916) and FlhorBan 918 (F918), created by CIRAD`s banana breeding programme, using two different approaches. The first approach was used with F916 and involved calculating the base temperature of bunches sampled at two sites at the ripening stage, and then determining the thermal sum at which the stage of maturity would be identical to that of the control Cavendish export banana. The second approach was used to assess the harvest stage of F918 and involved calculating the two thermal parameters directly, but using more plants and a longer period. Using the linear regression model, the estimated thermal parameters were a thermal sum of 680 degree-days (dd) at a base temperature of 17.0 degrees C for cv. F916, and 970 dd at 13.9 degrees C for cv. F918. This easy-to-use method provides quick and reliable calculations of the two thermal parameters required at a specific harvesting stage for a given banana variety in tropical climate conditions. Determining these two values is an essential step for gaining insight into the agronomic features of a new variety and its potential for export. (C) 2011 Elsevier B.V. All rights reserved.

Effect of inulin and Lactobacillus paracasei on sensory and instrumental texture properties of functional chocolate mousse

BACKGROUND: This study evaluated the effect of a potentially probiotic bacteria (Lactobacillus paracasei subsp. paracasei LBC 82), added solely or together with the prebiotic ingredient inulin on instrumental texture attributes and sensory properties of a functional chocolate mousse during storage at 4 +/- 1 degrees C for up to 28 days. RESULTS: The addition of Lactobacillus paracasei resulted in a firmer and more adhesive chocolate mousse. This effect was intensified with the presence of inulin in the synbiotic formulation (5.24 N and -0.956 N, respectively, for firmness and adhesiveness after 28 days of storage) (P < 0.05). L. paracasei population did not vary (P > 0.05) during storage (always between 7.27 and 7.35 log cfu g(-1)), both for the probiotic and the synbiotic mousses. Synbiotic mousse differed from control and probiotic mousses during storage with respect to the color attribute. Moreover, both probiotic and synbiotic mousses presented taste, aroma and texture perceptions which were different from one another and from the control mousse after 14 and 21 days of storage. CONCLUSION: The use of inulin, together with the potentially probiotic strain of Lactobacillus paracasei subsp. paracasei, is advantageous, conferring potentially symbiotic potential to the chocolate mousse, as well as favorable texture and sensory properties. (c) 2008 Society of Chemical Industry.

Prevalence and characterization of Enterococcus spp. isolated from Brazilian foods

Enterococci can be used in the food industry as starter or probiotic cultures. However, enterococci are also implicated in severe multi-resistant nosocomial infections. In this study, the prevalence of enterococci in selected Brazilian foodstuffs (raw and pasteurized milk, meat products, cheeses and vegetables) was evaluated. Phenotypic and PCR protocols were used for species identification. Tests for production of gelatinase, haemolysin, bacteriocin and bile salt hydrolysis were done with all enterococci isolates, whereas molecular determination of virulence markers (genes esp, gel, ace, as, efaA, hyl and cylA) and antibiotic resistance was checked only for Enterococcus faecium and Enterococcus faecalis isolates. The antibiotic-resistant isolates were assayed for biofilm formation and adhesion to mammalian cells. From the 120 food samples analyzed, 52.5% were positive for enterococci, meat and cheese being the most contaminated. E. faecium was the predominant species, followed by E. faecalis, E. casseliflavus and Enterococcus gallinarum. Phenotypic tests indicated that 67.7% of isolates hydrolyzed bile salts, 15.2% produced bacteriocin, 12.0% were beta-hemolytic and 18.2% produced gelatinase. Antibiotic resistance (gentamicin, tetracycline and erythromycin) and genes encoding for virulence traits were more frequent in E. faecalis than in E. faecium. Three E. faecium isolates were resistant to vancomycin. Among antibiotic-resistant isolates, 72.4% of E. faecalis were able to form biofilm and 13.8% to adhere to Caco-2 cells. Antibiotic-resistant E. faecalis and E. faecium isolates were grouped by RAPD-PCR and a scattered distribution was noted, indicating that resistance was not related to a particular clone. The spread of virulence/resistance traits in isolates of the two species and different RAPD-types suggest the pathogenic potential of both species. By contrast, the recovery of bacteriocinogenic E. faecium isolates with no virulence traits suggests their potential for biotechnological applications. In conclusion, our results showed that enterococci from Brazilian foods present important dualist aspects for food safety. (C) 2008 Elsevier Ltd. All rights reserved.

Low temperature induced changes in activity and protein levels of the enzymes associated to conversion of starch to sucrose in banana fruit

Storage at low temperature is the most frequently used method to extend the shelf life of banana fruit, and is fundamental for extended storage and transport over long distances. However, storage and transport conditions must be carefully controlled because of the high susceptibility of many commercial cultivars to chilling injury. The physiological behavior of bananas at low temperatures has been studied to identify possible mechanisms of resistance to chilling injury. The aim of this work was to evaluate differences in the starch-to-sucrose metabolism of a less tolerant and susceptible (Musa acuminata, AAA cv. Nanicao) and a more tolerant (M. acuminata x Musa balbusiana, AAB, cv. Prata) banana cultivar to chilling injury. Fruits of these cultivars were stored in chambers at 13 degrees C for 15 d, at which point they were transferred to 19 degrees C, where they were left until complete ripening. The low temperature induced significant changes in the metabolism of starch and sucrose in comparison to fruit ripened only at 19 degrees C. The sucrose accumulation was slightly higher in cv. Prata, and different patterns of starch degradation, sucrose synthesis, activity and protein levels of the alpha-and beta-amylases, starch phosphorylase, sucrose synthase and sucrose phosphate synthase were detected between the cultivars. Our results suggest that starch-to-sucrose metabolism is likely part of the mechanism for cold acclimation in banana fruit, and the cultivar-dependent differences contribute to their ability to tolerate cold temperatures. (C) 2011 Elsevier B.V. All rights reserved.

In vivo degradation of banana starch: Structural characterization of the degradation process

This work reports the first ultrastructural investigation into the degradation process that starch granules isolated from bananas (cv. Nanicao) undergo during ripening. Starch granules from green bananas had a smooth surface, while granules from ripe bananas were more elongated with parallel striations, as revealed by CSLM and SEM. AFM images revealed that the first layer covering the granule surface is composed of a hard material and, as degradation proceeds, hard and soft regions seem to be repeated at regular intervals. WAXD patterns of banana starches were C-type, and the crystalline index was reduced during ripening. The B-/A-type ratio was increased, indicating the preferential degradation of the A-type allomorph. The branch-chain length distribution showed predominantly short chains of amylopectin (A and B1-chain). The fa/fb ratio was reduced during degradation, while amylose content was increased. The results allowed a detailed understanding of the changes that starch granules undergo during banana ripening. (C) 2010 Elsevier Ltd. All rights reserved.

Synthesis of Fructooligosaccharides in Banana `Prata` and Its Relation to Invertase Activity and Sucrose Accumulation

Levels of sucrose and total fructool igosaccha rides (FOS) were quantified in different phases of banana `Prata` ripening during storage at ambient (similar to 19 degrees C) and low (similar to 10 degrees C) temperature. Total FOS levels were detected in the first days after harvest, whereas 1-kestose remained undetectable until the sucrose levels reached approximately 200 mg/g (dry weight) in both groups. Sucrose levels increased slowly but constantly at low temperature, but they elevated rapidly when the temperature was raised to 19 degrees C. Total FOS and sucrose levels were higher in bananas stored at low temperature than in the control group. In both samples, total FOS levels were higher than those of 1-kestose. The carbohydrate profiles obtained by HPLC and TLC suggest the presence of neokestose, 6-kestose, and bifurcose. The enzymes putatively involved in banana fructosyltransferase activity were also evaluated. Results obtained indicate that the banana enzyme responsible for the synthesis of FOS by transfructosylation is an invertase rather than a sucrose-sucrosyl transferase-like enzyme.

Plantain and Banana Starches: Granule Structural Characteristics Explain the Differences in Their Starch Degradation Patterns

Different banana cultivars were used to investigate the influences of starch granule structure and hydrolases on degradation. The highest degrees of starch degradation were observed in dessert bananas during ripening. Scanning electron microscopy images revealed smooth granule surface in the green stage in all cultivars, except for Mysore. The small and round granules were preferentially degraded in all of the cultivars. Terra demonstrated a higher degree of crystallinity and a short amylopectin chain length distribution, resulting in high starch content in the ripe stage. Amylose content and the crystallinity index were more strongly correlated than the distribution of amylopectin branch chain lengths in banana starches. alpha- and beta-amylase activities were found in both forms, soluble in the pulp and associated with the starch granule. Starch-phosphorylase was not found in Mysore. On the basis of the profile of alpha-amylase in vitro digestion and the structural characteristics, it could be concluded that the starch of plantains has an arrangement of granules more resistant to enzymes than the starch of dessert bananas.

Mango starch degradation. II. The binding of alpha-amylase and beta-amylase to the starch granule

During mango ripening, soluble sugars that account for mango sweetening are accumulated through carbon supplied by both photosynthesis and starch degradation. The cultivar Keitt has a characteristic dependence on sugar accumulation during starch degradation, which takes place during ripening, only a few days after detachment from the tree. Most knowledge about starch degradation is based on seeds and leaves currently used as models. However, information about the mango fruit is scarce. This work presents the evaluation of alpha- and beta-amylases in the starch granule surface during fruit development and ripening. Extractable proteins were assayed for amylase activity and detected by immunofluorescence microscopy and correlated to gene expression. The results suggest that both amylases are involved in starch degradation during mango ripening, probably under the dependence of another signal triggered by the detachment from the mother-plant.

Identification of fructooligosaccharides in different banana cultivars

Banana has been currently indicated as a good source of fructooligosaccharides (FOS), which are considered to be functional components of foods. However, significant differences in their amounts in bananas have been observed in the literature. This work aims to identify and quantify FOS during ripening in different banana cultivars belonging to the most common genomic groups cultivated in Brazil. Considering that these differences can be due to cultivar, stage of ripening, and the methodologies used for FOS analyses, sugar contents were analyzed by high performance anion exchange chromatography-pulsed amperometric detection (HPAEC-PAD) and gas chromatography-mass spectrometry (GC-MS). An initial screening of eight cultivars (Ouro, Nanicao, Prata, Maca, Mysore, Pacovan, Terra, and Figo) in a full-ripe stage showed that 1-kestose, the first member of the FOS series (amounts between 297 and 1600 mu g/g of DM), was accumulated in all of them. Nystose, the second member, was detected only in Prata cultivar. Five of the cultivars were analyzed during ripening, and a strong correlation could be established with a specific sucrose level (similar to 200 mg/g of DM), which seems to trigger the synthesis of 1-kestose (the low amounts of FOS, below the functional recommended dose, indicates that banana cannot be considered a good source of FOS).

Correlation between mastitis occurrence and the count of microorganisms in bulk raw milk of bovine dairy herds in four selective culture media

Milk is the normal secretion of the mammary gland, practically free of colostrum and obtained by the complete milking of oil(? or more healthy animals. Mastitis is all inflammatory process of the mammary gland and it may cause alterations in the milk. The present work aimed to verify whether it is possible, by means of the counts of microorganism in the bulk raw milk ill four selective culture media, to establish a correlation with the occurrence of mastitis and therefore, to monitor this disease in bovine dairy herds. The following selective culture media were Used: KF Streptococcus Agar, Edwards Agar, Baird-Parker Agar, Blood Agar plus potassium tellurite. Spearman`s correlation coefficient was calculated in order to compare the Occurrence of mastitis (percentage) in each herd with respective selective culture media counts of microorganisms in bulk raw milk. Thirty-six possibilities were analysed (Tamis and CMT-positive rates were compared with the log-transformed count in four selective Culture media) and there was a negative correlation between Tamis 3 and the Baird-Parker Agar plate count. The total results of microbiological tests showed that there were three correlations of the counts in selective culture media. Fifty-two possibilities were analysed and there was a negative correlation between no-bacteria I-growth mastitis rates and log(10) of KF Streptoccocus Agar plate Count and there were two positive correlations between coagulase-positive staphylococci and log(10) of Baird-Parker Agar plate count and Blood Agar plus potassium tellurite plate count.

Effect of agitation on the performance of an anaerobic sequencing batch biofilm reactor in the treatment of dairy effluents

Agitation rate is an important parameter in the operation of Anaerobic Sequencing Biofilm Batch Reactors (ASBBRs), and a proper agitation rate guarantees good mixing, improves mass transfer, and enhances the solubility of the particulate organic matter. Dairy effluents have a high amount of particulate organic matter, and their anaerobic digestion presents inhibitory intermediates (e. g., long-chain fatty acids). The importance of studying agitation in such batch systems is clear. The present study aimed to evaluate how agitation frequency influences the anaerobic treatment of dairy effluents. The ASBBR was fed with wastewater from milk pasteurisation process and cheese manufacture with no whey segregation. The organic matter concentration, measured as chemical oxygen demand (COD), was maintained at approximately 8,000 mg/L. The reactor was operated with four agitation frequencies: 500 rpm, 350 rpm, 200 rpm, and no agitation. In terms of COD removal efficiency, similar results were observed for 500 rpm and 350 rpm (around 90%) and for 200 rpm and no agitation (around 80%). Increasing the system`s agitation thus not only improved the global efficiency of organic matter removal but also influenced volatile acid production and consumption and clearly modified this balance in each experimental condition.

Effect of processing on amine formation and the lipid profile of cod (Gadus morhua) roe

The processing of fish roe leads to changes in its chemical composition, the extent of which depends on the techniques and additives employed. This study aimed to investigate the effects of ripening temperature and the use of sodium benzoate and citric acid on the quality of ripened cod roe, with respect to the contents of volatile base nitrogen (VBN), trimethylamine (TMA), biogenic amines (BA) and on the lipid composition. In comparison with fresh roes, ripened roes presented higher contents of VBN, TMA, BA and the proportion of free fatty acids regardless of the temperature and additives used during the ripening process. The greatest increases were observed in the samples ripened at 17 degrees C without additives, in which histamine was detected at 8.8 mg/100 g. A low ripening temperature was the main factor responsible for minimising changes in the cod roe composition. The addition of sodium benzoate as a preservative or citric acid to decrease the pH value had a significant effect in maintaining the quality of the cod roes, mainly at high ripening temperature. (C) 2011 Elsevier Ltd. All rights reserved.

A comparison of two bench-scale anaerobic systems used for the treatment of dairy effluents

The objective of this work was to compare two anaerobic reactor conflgurations, a hybrid upflow anaerobic sludge blanket (UASBh) reactor and an anaerobic sequencing batch reactor with immobilised biomass (ASBBR) treating dairy effluents. The reactors were fed with effluent from the milk pasteurisation process (effluent 1-E1) and later with effluent from the same process combined with the one from the cheese manufacturing (effluent 2-E2). The ASBBR reactor showed average organic matter removal efficiency of 95.2% for E1 and 93.5% for E2, while the hybrid UASB reactor showed removal efficiencies of 90.3% and 80.1% respectively.

A new processing method of CaZn(2)(OH)(6)center dot 2H(2)O powders: Photoluminescence and growth mechanism

In this communication, we report on the formation of calcium hexahydroxodizincate dehydrate, CaZn(2)(OH)(6)center dot 2H(2)O (CZO) powders under microwave-hydrothermal (MH) conditions. These powders were analyzed by X-ray diffraction (XRD), Field-emission gum scanning electron microscopy (FEG-SEM), ultraviolet-visible (UV-vis) absorption spectroscopy and photoluminescence (PL) measurements. XRD patterns confirmed that the pure CZO phase was obtained after MH processing performed at 130 degrees C for 2 h. FEG-SEM micrographs indicated that the morphological modifications as well as the growth of CZO microparticles are governed by Ostwald-ripening and coalescence mechanisms. UV-vis spectra showed that this material have an indirect optical band gap. The pure CZO powders exhibited an yellow PL emission when excited by 350 nm wavelength at room temperature. (C) 2009 Elsevier Masson SAS. All rights reserved.