Purification and Characterization of Mannanase from Aspergillus awamori for Fruit Juice Clarification

BACKGROUND

Fruit juice clarification is a challenging aspect of beverage industry which needs to be addressed for economical and hygienic production of fruit juices.

OBJECTIVE

Current study is focused on the complete purification, characterization and thermodynamic analysis of an efficient mannanase enzyme to analyze its applicability in biological clarification fruit juice.

METHODS

Mannanase production using Aspergillus awamori IIB037 in a 25 L stirred fermenter at pre optimized reaction conditions was carried out. Enzyme purification was carried out via series of steps. Characterization of enzyme along with kinetics and thermodynamic studies was conducted. Purified and characterized enzyme was assessed for its applicability in fruit juice clarification through clarification experiments on fresh apple juice.

RESULTS

Purification fold of 3.98 was obtained along with 86.80% purification yield of mannanase with specific activity of 158.16 U/mg. The molecular size of purified enzyme was determined as 66 kDa. The enzyme depicted 56% residual activity at 60°C after 8 hrs. Thermodynamic studies of an enzyme revealed enthalpy of activation (ΔH) and activation energy (Ea) as 30.53KJ/mol, 27.76KJ/mol, respectively. The enzyme activity increased in the presence of ß-mercaptoethanol surprisingly. On the other hand, methyl alcohol, ethanol, Hg2+ and Cu2+ inhibited enzyme activity. The enzyme showed Km and Vmax values of 11.07 mM and 19.08 μM min-1 for Locust Bean Gum (LBG) under optimal conditions. Juice treated with mannanase showed decrease in absorbance and increase in reducing sugar content.

CONCLUSION

The current study demonstrated that mannanase from Aspergillus awamori in its purified form has significant characteristics to be employed industrially for juice clarification.

Protease produced by Lactobacillus brevis enhanced nutritional values of African yam beans and demonstrated improvement in the growth and blood indices of albino rats

This study evaluates the nutritional values of African yam bean hydrolyzed with protease from Lactobacillus brevis and afterward assess its effect on the growth and blood parameters of albino rats. The nutritional compositions of AYB hydrolyzed with partially purified protease from L. brevis were determined by standard chemical methods. The protease-hydrolyzed AYB was thereafter formulated into feeds with different inclusion levels (20, 40 and 60%), which was used to feed albino rats for 27 days. After the feeding trial, the blood of anesthetized albino rats was collected using the cardiac puncture method, and the hematological parameters were determined by standard biochemical methods. The AYB hydrolyzed with partially purified protease had the highest percentage crude protein with a value of 31.2% when compared with boiled, soaked and boiled, and raw sample with the values of 20.9, 20.9 and 19.9%, respectively. The treatment of AYB with purified protease also resulted in an increase of vitamins and some essential amino acids when compared with unhydrolyzed AYB. The group of rats fed with 60% hydrolyzed AYB had the highest percentage average weight gain of approximately 144%, while the values recorded for the groups fed with commercial feed and unhydrolyzed AYB were approximately 86 and 101%, respectively. The hematological analysis revealed that the hemoglobin (Hb) and packed cell volume (PCV) of the group fed with 40% hydrolyzed AYB of 14 g/L and 38% respectively, were significantly higher than the rats fed with commercial feed with values of 10 g/L and 32%, respectively. Thus, enzyme-hydrolyzed AYB might be a suitable alternative to animal protein with good functional properties.