Purification of pectinase from mango (Mangifera indica L. cv. Chokanan) waste using an aqueous organic phase system: a potential low cost source of the enzyme.

As a novel method of purification, an aqueous organic phase system (AOPS) was employed to purify pectinase from mango waste. The effect of different parameters, such as the alcohol concentration (ethanol, 1-propanol, and 2-propanol), the salt type and concentration (ammonium sulfate, potassium phosphate and sodium citrate), the feed stock crude load, the aqueous phase pH and NaCl concentration, were investigated in the recovery of pectinase from mango peel. The partition coefficient (K), selectivity (S), purification factor (PF) and yield (Y, %) were investigated in this study as important parameters for the evaluation of enzyme recovery. The desirable partition efficiency for pectinase purification was achieved in an AOPS of 19% (w/w) ethanol and 22% (w/w) potassium phosphate in the presence of 5% (w/w) NaCl at pH 7.0. Based on the system, the purification factor of pectinase was enhanced 11.7, with a high yield of 97.1%.

Extraction of bromelain from pineapple peels.

Large amount of pineapple peels (by-products) is left over after processing and they are a potential source for bromelain extraction. Distilled water (DI), DI containing cysteine and ethylenediaminetetraacetic acid (EDTA) (DI-CE), sodium phosphate buffer pH 7.0 (PB) and PB containing cysteine and EDTA (PB-CE) were used as extractants for bromelain from the pineapple peels. The highest bromelain activity was obtained when it was extracted with PB-CE (867 and 1032 units for Nang Lae and Phu Lae cultv, respectively). The PB could maintain the pH of the extract (pH 5.1-5.7) when compared with others. Under sodium dodecyl sulfate polyacrylamide gel electrophoresis, the extract showed protein bands in the range 24-28 kDa. The protein band with a molecular weight of ∼28 kDa exposed the clear zone on blue background under the casein-substrate gel electrophoresis. The effects of the bromelain extract on the protein patterns of beef, chicken and squid muscles were also determined. Trichloroacetic acid soluble peptide content of all the treated muscles increased when the amount of bromelain extract increased. Decrease in myosin heavy chains and actin was observed in all the muscle types when bromelain extract was used. The best extractant for bromelain from pineapple peels was PB-CE. Moreover, bromelain extract could be used as a muscle food tenderizing agent in food industries.

Effects of dense phase carbon dioxide pasteurization on the physical and quality attributes of a red grapefruit juice.

Red grapefruit juice was treated with continuous dense phase carbon dioxide (DPCD) equipment to inactivate yeasts and molds and total aerobic microorganisms. A central composite design was used with pressure (13.8, 24.1, and 34.5 MPa) and residence time (5, 7, and 9 min) as variables at constant temperature (40 degrees C), and CO(2) level (5.7%) after experimentally measuring CO(2) solubility in the juice. Five log reduction for yeasts and molds and total aerobic microorganisms occurred at 34.5 MPa and 7 min of treatment. A storage study was performed on the fresh juice DPCD treated at these conditions. degrees Brix, pH, titratable acidity (TA), pectinesterase (PE) inactivation, cloud, color, hue tint and color density, total phenolics, antioxidant capacity, and ascorbic acid were measured after the treatment and during 6 wk storage at 4 degrees C. During storage, the DPCD-treated juice showed no growth of total aerobic microorganisms and yeasts and molds. Cloud increased (91%) while percent PE inactivation was partial (69.17%). No significant (alpha= 0.05) differences were detected between treated and untreated samples for degrees Brix, pH, and TA. Treated juice had higher lightness and redness and lower yellowness. No significant differences (alpha= 0.05) were detected for the hue tint values while the color density value was higher for the treated samples compared to the untreated. The treatment and the storage did not affect the total phenolic content of the juice. Slight differences were detected for the ascorbic acid content and the antioxidant capacity. The experimental results showed evidence that the treatment can maintain the physical and quality attributes of the juice, extending its shelf life and safety.

Production of L-lactic acid and oligomeric compounds from apple pomace by simultaneous saccharification and fermentation: a response surface methodology assessment.

The potential of apple pomace for lactic acid production by simultaneous saccharification and fermentation (SSF) was evaluated. The effects of the cellulase to solid ratio (CSR), the liquor to solid ratio (LSR), and the beta-glucosidase to cellulase ratio (BCR) on the kinetics of lactic acid generation were assessed, and a set of mathematical models was developed to reproduce and predict the lactic acid concentration of fermentation broths. Operating at low cellulase and cellobiase charges (1 FPU/g and 0.25 IU/FPU, respectively) and short reaction times (10 h), SSF media containing 27.8 g of lactic acid/L were obtained with a volumetric productivity of 2.78 g/Lh. Material balances showed that the SSF processing of 100 kg of dry apple pomace results in the production of 36.6 kg of lactic acid, 18.3 kg of oligomeric carbohydrates (which can be used as ingredients for functional foods), 8.4 kg of microbial biomass, and 8 kg uronic acids.

Molecular cloning and characterization of a novel 1-aminocyclopropane-1-carboxylate oxidase gene involved in ripening of banana fruits.

One novel banana fruit ripening related 1-aminocyclopropane-1-carboxylate (ACC) oxidase gene quite different from ACC oxidase genes from other species was cloned. In contrast to other studies, the polypeptide encoded by this gene, named Mh-ACO1, lacks the putative leucine zipper motif which is conserved in all known ACC oxidases including the other previously reported banana ACC oxidase, Mh-ACO2. The locus consists of two nearly identical paralogous ACC oxidase genes arranged in opposite orientation and separated by a 3.1-kb intergenic region. The has only two introns, at positions identical to , which comprises a coding region interrupted by three introns. The predicted amino acid sequence of Mh-ACO1 shares less than 50% identity to those of ACC oxidase from other climacteric fruits, while that of Mh-ACO2 shows more than 65% homology. When expressed in Saccharomyces cerevisiae -encoded protein possessed the enzyme activity for ethylene conversion. The levels of mRNA corresponding to both and increased during fruit ripening and were induced by exogenous ethylene. We conclude that both and contribute to increased ethylene production in fruits and these two genes are differentially expressed in fruits and other organs in banana.