BLT Stages

Abstract bachelorproef 1 2015-2016: Optimisation of Parameters for fermentative Wine Production from Grapes

Fruits can be processed by making fruit wine by fermentation. The winemaking process includes three steps, namely the pre-fermentation, fermentation and post-fermentation stages. In the first step the fruits are prepared and yeast is added, which will initiate the second phase. Parameters in these steps have already been discussed by many authors (Swami, Thakor, & Divate, 2014). The present study has been designed to optimise parameters for wine production. In the post- fermentation phase the fermentation product can undergo treatments, mainly in order to improve the taste. An example of this is reducing acidity by adding salts or sugar.

It has been found that particularly red wine provides beneficial health effects to people (Opie & Lecour, 2007) such as antioxidant activity or protection against cardiovascular diseases and myocardial infarcts. Apart from optimising the post-fermentation parameters, the purpose of this study is to verify the antioxidant activity wine and to find out components responsible for these properties.

In this research wine was produced by using baker’s yeast (Saccharomyces cerevisiae) for fermentation. During the fermentation phase parameters such as acidity (pH and titrable acidity) and sugar content were monitored. The fermentation product was then analysed with Attenuated Total Reflectance Fourier Transform Infrared spectrometry (ATR FT-IR) and High Performance Liquid Chromatography (HPLC) in order to analyse the components. This was followed by the determination of the antioxidant capacity of the samples. As an additional experiment a gel filtration was performed on the wine sample followed by an antioxidant assay. Eventually the wine was evaluated by a test panel to check the taste and whether it is suitable for human consumption.

Some post-fermentation parameters were also optimised. Initially, the termination of fermentation by chill treatment (-18 °C for at least 72 hours) was found to be effective as the ethanol evaporates during filtration processes. Another parameter is clarification of the wine. Centrifugation at 6000 rounds per minute (rpm) for 10 minutes was found optimal for clarification of the wine. Thirdly, deacidification of the wine was also done using salts to neutralise citric, malic and tartaric acid (Prescott & Dunn, 1982).

After applying these parameters, the sensory evaluation of the wine was found to be good which means that it is suitable for human consumption.

Results of the antioxidant assay shows that red wine’s activity was significantly higher than white wine’s. After the gel filtration it was revealed that this activity is mainly due to presence of polyphenols (resveratrol), amines and C – O – C esters and polysaccharides (C – O).

From this study it can be concluded that the wine can be consumed and is good for health at some points.

Abstract bachelorproef 2 2015-2016: Isolation and screening of bacteria for Amylase production

Amylases are one of the most important enzymes and are of great significance for the biotechnology. Industrial enzymes are constituting approximately 25 % of the world enzyme market. The need for new amylase producing microbial strains and improved enzyme production technology has attracted attention due to its increasing application in the food, paper, brewing, detergent and textile industry.
This study evaluates the isolation and screening of an amylase producing bacteria obtained from a potato sample. After primary, secondary and tertiary screening the isolate with the highest activity was selected for laboratory scale production and for further purification. Identification of the isolate was done by using the staining according to Gram. The amylase producing bacteria was identified as a rod shaped, Gram positive and motile bacteria. Further characterization was not obtained as a part of this study.
The specific activity of both the crude and purified enzymes were determined by using DNS assay and Lowry method. The isolates were monitored under stationary and shaking conditions. It was found that the results under shaking conditions were significantly higher as compared to the activity under stationary conditions. Maximum enzyme activity was obtained after five days of incubation under shaking conditions at 50 rpm. Ultra-sonication technique was used for cell disruption for intracellular enzyme extraction.
After isolation and screening of the bacteria, purification was done. Purification of the amylase producing bacteria is achieved by following a purification process. The purification process includes three different techniques: ammonium sulphate precipitation, dialysis and gel filtration. In this study, ammonium sulphate precipitation with a saturation of 60 % was found to be optimum to purify the isolate. As a final purification step, gel filtration with Sephadex G-50 was performed. The fraction with the highest activity had an amylase enzyme activity of 37.03 IU/mL and a specific activity of 91.65 IU/mg. The molecular weight of this fraction and the purified enzyme was estimated to be 85.960 kDa using SDS-PAGE.
The found amylase producing bacteria can be used in several applications according to the size and enzyme activity. In order to determine in which particular application, further screening and testing is necessary.