Removal of patulin from apple juice using inactivated lactic acid bacteria

Aims: Apples and apple products are the most notably commodities contaminated with patulin (PAT), which cause detrimental effects on human health and economic problems. The primary objective of this study was to investigate the removal of PAT contamination from apple juice using 10 different inactivated lactic acid bacteria (LAB) strains. Methods and Results: Significant quantities of PAT ranging from 47 to 80% were bound to all tested bacterial strains, whereas Lactobacillus rhamnosus 6224 and Enterococcus faecium 21605 caused a decrease of PAT by 80·4 and 64·5%, respectively. The results showed that the binding of PAT depends on the initial concentration of toxin and the adsorption temperature, also the differences in biomass existed among the 10 bacterial strains. IR analysis was performed to identify potential functional groups and the possible binding sites related to PAT adsorption. Conclusions: The removal of PAT was observed to be strain specific. The results indicated that the biosorption process did not affect the quality of juice. FTIR analysis showed that the cell wall plays a key role in PAT adsorption. Significance and Impact of the Study: Our results proof that inactivated LAB have the potential as a novel and promising adsorbent to bind PAT effectively.     

Bacterial wilt, a new disease of custard apple: symptoms and etiology

Pseudomonas solanacearum biovar 3 was identified as the causal agent of two disease syndromes in custard apples (Annona spp.), namely sudden death of young trees and the decline of mature trees. Cross inoculation tests using cultures of P. solanacearum from custard apple and tomato on A. squamosa, A. squamosa×A. cherimola hybrids, Capsicum annuum, three cultivars of Lycopersicon esculentum and Solanum tuberosum failed to distinguish differences in virulence among these isolates. Bacterial wilt resistant rootstock clones, particularly of A. cherimola, constitute the most effective control measure available.     

An optical biosensor employing tiron-immobilised polypyrrole films for estimating monophenolase activity in apple juice

A method is described for the incorporation of tiron as a substrate for tyrosinase enzyme into a polypyrrole film deposited on indium titanium oxide (ITO) glass. The presence of tiron in the polypyrrole film is verified by cyclic voltammetry (CV). The enzyme activity using the polypyrrole-tiron film is confirmed by the catalytic conversion of immobilised substrate to quinones by the enzyme. The use of both potentiometric and optical methods for the detection of the catalytic activity of the polypyrrole-tiron film and their potential use for the determination of monophenolase activity of apple polyphenol oxidase is described. This is the first report of this kind whereby tiron has been immobilised in a polypyrrole matrix for the enzyme activity determination.     

Influence of pectinase treatment on fruit spirits from apple mash, juice and pomace

The current investigation was conducted to determine the influence of pectinase treatment on fruit spirits produced from apple mash, juice, and pomace. Crispin apples were processed into apple mash, juice, and pomace in our pilot-plant, and fermented with a commercial Red Star wine yeast (Sachharomyces cerevisiae Davis 904). After fermentation, the samples of fermented apple mash, juice, and pomace were distilled, and the distillates were analyzed by HPLC with a Bio-Rad Aminex HPX 87H column and a refractive index detector. Methanol, ethanol, n-propanol, iso-butanol, and iso-amyl alcohol were identified as the major alcohols in all the apple spirits. Student's t-test results indicate that there are significant differences between the methanol concentrations of pectinase treated and non-pectinase treated apple spirits. Duncan's multiple range tests show significant differences in the concentrations of methanol of the fruit spirits made from apple mash, juice, and pomace. Apple pomace yielded significantly higher methanol concentrations than apple mash and juice. Pectinase treatment had little effect on the concentrations of n-propanol, iso-butanol, and iso-amyl alcohol. It is concluded that fruit spirits made from the pectinase treated mash, juice, and pomace of Crispin apples had methanol concentrations significantly above the United States FDA guidance of 0.35% by volume or 280 mg/100 mL of fruit brandy containing 40% ethanol.     

Continuous fermentation of apple juice by immobilized yeast cells

Summary The sugar content of an apple juice was continuously converted into ethanol bySaccharomyces cerevisiae entrapped in Ca-alginate gel. The average values characterizing the process were: fermentation efficiency, 84.7±4.2%, ethanol concentration in the mash, 38.9–1.9 g·l^–1 and volumetric productivity, 6.3±0.5 g·l^–1·h^–1.     

Microbiological quality of walnut kernels and apple juice concentrate

In the present study, we have evaluated the microbiological quality of walnut kernels and pasteurized apple juice concentrate and the application of PCR for quality control of these important horticultural products. PCR assays for the detection of Bacillus cereus, Salmonella, Escherichia coli and E. coli O157:H7 were standardized using minimum time for each step of the reaction. The protocols were effective for their detection in these products after pre-enrichment for 6–12 h. 2, 68 and 30% of the samples of walnut kernels were respectively found satisfactory, acceptable and unsatisfactory on the basis of their viable count. Only 15% of the samples of pasteurized apple juice concentrate were found to possess the desired viable count of less than 100 c.f.u./ml. The predominant contaminants of walnut kernels were found to be the species of Bacillus, Klebsiella, Enterobacter and Staphylococcus. Samples of apple juice concentrate were predominantly found contaminated with species of Bacillus, Staphylococcus and Micrococcus. However, B. cereus, Salmonella and E. coli were also isolated from some of the samples of walnut kernels. Bacillus cereus was also obtained from some of the samples of pasteurized apple juice concentrate in high numbers. Among the moulds Penicillium, Aspergillus, Cladosporium, Rhizopus and Mucor were isolated from these products.     

Phenols removal from apple juice by laccase immobilized on Cu 2+ -chelate regenerable carrier

Laccase (EC. 1.10.3.2.) immobilized on Sepharose 4B-Epi-IDA-Cu -chelate carrier removed, respectively, 39 and 48% of phenols and flavanols from apple juice using starting carrier, while the enzyme removed 34 and 44% with the regenerated carrier.     

Disappearance of patulin during alcoholic fermentation of apple juice.

Eight yeast strains were used in three typical American processes to ferment apple juice containing 15 mg of added patulin per liter. Patulin was reduced to less than the minimum detectable level of 50 microgram/liter in all but two cases; in all cases, the level of patulin was reduced by over 99% during alcoholic fermentation. In unfermented samples of apple juice, the concentration of added patulin declined by only 10% when the juice was held for 2 weeks, a period equivalent to the time required for fermentation.     

Disappearance of patulin during alcoholic fermentation of apple juice.

Eight yeast strains were used in three typical American processes to ferment apple juice containing 15 mg of added patulin per liter. Patulin was reduced to less than the minimum detectable level of 50 microgram/liter in all but two cases; in all cases, the level of patulin was reduced by over 99% during alcoholic fermentation. In unfermented samples of apple juice, the concentration of added patulin declined by only 10% when the juice was held for 2 weeks, a period equivalent to the time required for fermentation.     

Enzyme synthesis of oligosaccharides using cashew apple juice as substrate

The use of agriculture substrates in industrial biotechnological processes has been increasing because of their low cost. In this work, the use of clarified cashew apple juice was investigated as substrate for enzyme synthesis of prebiotic oligosaccharide. The results showed that cashew apple juice is a good source of reducing sugars and can be used as substrate for the production of dextransucrase by Leuconostoc citreum B-742 for the synthesis of oligosaccharides using the crude enzyme. Optimal oligosaccharide yield (approximately 80%) was obtained for sucrose concentrations lower than 60 g/L and reducing sugar concentrations higher than 100 g/L.     

Acyl-CoA oxidase from Candida tropicalis

The preparation of a highly purified acyl-CoA oxidase from the cell extract of an n-alkane-utilizing yeast, Candida tropicalis, is described. It can be crystallized from ammonium sulfate solutions without an increase in specific activity, and is homogeneous on ultracentrifuge and disc electrophoresis. The enzyme is an octamer with approximately a 600,000 molecular weight, and has an isoelectric point of 5.5. It exhibits a typical flavoprotein spectrum with absorption maxima at 277, 365 and 445 nm, and contains 8 mol of FAD per mol of enzyme. The enzyme catalyzes the stoichiometric conversion of palmitoyl-CoA and O₂ into 2-hexadecenoyl-CoA and H₂O₂. It oxidizes acyl-CoAs with carbon chain lengths of 4 to 20, and is most active toward lauroyl-CoA, but acetyl- and succinyl-CoAs are not oxidized. The enzyme is sulfhydryl dependent and is inactivated by silver and mercury compounds.     

Acyl-CoA oxidase from Candida tropicalis

Acyl coenzyme A oxidase (acyl-CoA oxidase) has been isolated in good yield from Candida tropicalis pK 233 grown on n-alkanes. Gel filtration, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and measurement of flavin content suggest that the oxidase is an octamer of Mr 75 000 subunits each containing one flavin. The oxidase yields the red semiquinone form on dithionite or photochemical reduction, slowly forms an N-5 adduct with 0.16 M sulfite at pH 7.4, and is rapidly reduced by borohydride, forming the 3,4-dihydroflavin isomer. The red flavosemiquinone is only kinetically stabilized with respect to disproportionation in the free enzyme but is thermodynamically stabilized on binding enoyl-CoA derivatives. The enzyme is reduced by butyryl-, octanoyl-, and palmitoyl-CoA without formation of prominent long-wavelength bands. Acyl-CoA oxidase and the acyl-CoA dehydrogenases share many similarities in their interaction with CoA derivatives. For example, both enzymes stabilize the anionic radical on binding enoyl-CoA derivatives, both dehydrogenate 2-oxoheptadecyldethio-CoA but cannot utilize S-heptadecyl-CoA, both form long-wavelength bands with CoA persulfide species, and both enzymes are attacked by the suicide substrates 3,4-pentadienoyl-CoA and (methylene-cyclopropyl)acetyl-CoA at the flavin prosthetic group.     

Immobilization of polygalacturonase from Aspergillus niger onto activated polyethylene and its application in apple juice clarification

The present work is focused on efficient immobilization of polygalacturonase on polyethylene matrix, followed by its application in apple juice clarification. Immobilization of polygalacturonase on activated polyethylene and its use in apple juice clarification was not reported so far. Aspergillus niger Van Tieghem (MTCC 3323) produced polygalacturonase when grown in modified Riviere's medium containing pectin as single carbon source by fed-batch culture. The enzyme was precipitated with ethanol and purified by gel filtration chromatography (Sephacryl S-100) and immobilized onto glutaraldehyde-activated polyethylene. The method is very simple and time saving for enzyme immobilization. Various characteristics of immobilized enzyme such as optimum reaction temperature and pH, temperature and pH stability, binding kinetics, efficiency of binding, reusability and metal ion effect on immobilized enzymes were evaluated in comparison to the free enzyme. Both the free and immobilized enzyme showed maximum activity at a temperature of 45 degrees C and pH 4.8. Maximum binding efficiency was 38%. The immobilized enzyme was reusable for 3 cycles with 50% loss of activity after the third cycle. Twenty-four U of immobilized enzyme at 45 degrees C and 1 h incubation time increased the transmittance of the apple juice by about 55% at 650 nm. The immobilized enzyme can be of industrial advantage in terms of sturdiness, availability, inertness, low price, reusability and temperature stability.