The improvement of grape juice quality using Thermomucor Indicae-Seudaticae pectinase.

The effect of pectinolytic enzyme preparation (PEP) produced by the fungus Thermomucor indicae-seudaticae-N31 (PEP-N31) on total phenolic content, concentrations of methanol and color of grape juice was studied. Positive results were found when PEP-N31 was used to extract phenolic compounds after the grapes had been blanched for 3 min and macerated for 1 h. The resulting juice had better yield, color characteristics and higher phenolic content (1637.21 mg.L-1, as gallic acid equivalent, or GAE) than the conventionally prepared juice (1422.59 mg GAE.L-1), and it was very similar to the juice obtained through the treatment with a commercial enzyme (1682.10 mg GAE.L-1). The concentration of methanol in the juice produced with the PEP-N31 was less than 200 mg.L-1. These results encourage the use of PEP produced by Thermomucor indicae-seudaticae-N31 by the grape-processing industry.

Evaluation of the use of Syzygium cumini fruit extract as an antioxidant additive in orange juice and its sensorial impact.

This work is an exploratory study of the possibility of promoting the consumption of Syzygium cumini fruit by adding its extract to orange juice making good use of its functional (antioxidant) properties. S. cumini fruit extract was characterized in terms of its anthocyanin content (2.11 g/100 g expressed in cyanidine-3-glucoside equivalents), total phenolic compounds (360 mg/100 g expressed in gallic acid equivalents) and antioxidant capacity evaluated by the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging method. The effects of the addition of S. cumini fruit crude extract as well as its chromatographic fractions on the juice were assessed chemically by headspace solid-phase micro-extraction and gas chromatography coupled with a mass spectrometry detector. Only six compounds had their chromatographic peak intensities clearly changed and the results are discussed in terms of the inhibition of the formation of 2-octanone, hexanol, α-copaene, and α-panasinsene and the conservation of octyl acetate and p-menth-1-en-9-ol. Sensory evaluation of orange juice with and without S. cumini crude extract addition did not show any significant differences in the sensorial profile, discriminative and acceptance tests.

Wine aroma improvement using a ß-glucosidase preparation from Aureobasidium pullulans.

Microbial ß-glucosidases have been used for the enhancement of wine aroma. Nevertheless, few enzymes are active in the conditions of winemaking. In this work, the production of a ß-glucosidase by an Aureobasidium pullulans strain (Ap-ß-gl) isolated from grape ecosystems was evaluated. The maximum enzymatic synthesis using submerged fermentation was after 96 h of growth in complex media containing 20 g/L of cellobiose as the sole carbon source. The crude enzyme (Ap-ß-gl) showed optimal pH at 5.5 and two peaks of optimum temperature (at 45 and 70 °C). It showed a wide range of pH stability, stability at low temperatures, and tolerance to ethanol, showing suitable characteristics for winemaking conditions. The hydrolysis of glycosidic terpenes by Ap-ß-gl was studied, and its ability to efficiently release free terpenols was demonstrated by gas chromatography/mass spectrometry. The enzymatic treatment notably increased the amount of monoterpenes, showing good prospects for its potential application for the development of aroma in wines.

Purification and characterization of an ethanol-tolerant ß-glucosidase from Sporidiobolus pararoseus and its potential for hydrolysis of wine aroma precursors.

An extracellular ethanol-tolerant ß-glucosidase from Sporidiobolus pararoseus was purified to homogeneity and characterized, and its potential use for the enhancement of wine aroma was investigated. The crude enzymatic extract was purified in four steps (concentration, dialysis, ultrafiltration, and chromatography) with a yield of around 40 % for total activity. The purified enzyme (designated Sp-ßgl-P) showed a specific activity of approximately 20.0 U/mg, an estimated molecular mass of 63 kDa after sodium dodecyl sulfate polyacrylamide gel electrophoresis, and isoelectric point of 5.0 by isoelectric focusing. Sp-ßgl-P has optimal activity at pH 4.0 and at 55 °C. It was stable in a broad pH range at low temperatures and it was tolerant to ethanol and glucose, indicating suitable properties for winemaking. The hydrolysis of glycosidic terpenes was analyzed by adding Sp-ßgl-P directly to the wines. The released terpene compounds were evaluated by gas chromatography/mass spectrometry. The enzymatic treatment significantly increased the amount of free terpenes, suggesting that this enzyme could potentially be applicable in wine aroma improvement.

A novel ß-glucosidase from Sporidiobolus pararoseus: characterization and application in winemaking.

UNLABELLED: For the first time, the production of an extracellular ß-glucosidase (Sp-ß-gl) by a Sporidiobolus pararoseus yeast strain is reported. The Sp-ß-gl activity was quantified, characterized, and assessed for its efficiency in releasing aroma-enhancing compounds in wines. The maximum enzymatic synthesis was after 72 h of growth in a complex media with 20 g/L of cellobiose. The optimal pH and temperature were 5.5 and at 50 °C, respectively. It showed a wide range of pH stability and exhibited quite high thermostability at low temperatures. In addition, this ß-glucosidase revealed tolerance to wine-associated inhibitory compounds (sugars and ethanol), showing suitable characteristics for all the stages of alcoholic fermentation. The hydrolysis of the glycosidic terpenes by Sp-ß-gl was studied by gas chromatography, and its ability to efficiently release free terpenols has been demonstrated. The concentrations of geraniol, linalool, α-terpineol, and nerol were significantly increased in treated wines. These results suggest the potential application of this new yeast ß-glucosidase as an aroma-enhancing enzyme in winemaking. PRACTICAL APPLICATION: The search for new ß-glucosidase from yeast sources is important to improve the quality of wines. In this work, an S. pararoseus yeast strain has shown to be capable to produce a ß-glucosidase with suitable combination of properties for functionality in wines and with potential to increase the concentration of free aroma compounds, showing good prospects for an industrial application.