ABSTRACT
This research aimed to invent a new method for cheese making using Rennin-like enzyme from fungus with high efficiency and reusability. Accordingly, Rhizomucor miehei (CBS: 370.65) showed a promising milk clotting (MCF) activity and the mycotoxin test was negative. The partially purified enzyme was immobilized by entrapment in paraffin wax using different techniques. Wax-enzyme tablets preparation exhibited complete immobilization yield (100%). Ca2+ had a marked stimulating effect on the activities of both the free and immobilized enzyme forms. The immobilized enzyme (MCI) exhibited more than sixteen effective reuses to produce cheese in a batch reactor. The free and the immobilized forms recorded their optimum activities at pH 5.6 and 55 °C, respectively. The immobilization process reduced the consumed activation energy (Ea) to 39%. The immobilized enzyme was more stable than the free form. Among all the used substrates, buffalo milk and full cream milk showed the highest immobilized enzyme activity (7142.9 U). km value was unaffected by the immobilization process and was 600 mg reaction-1, for both. Schematic setup was used as semi-pilot example for a repeated batch of MCI wax tablets. This design solved the clotting problem completely by the refine bundle nominated its agreeability in the cheese-making process.
Subject(s)
Cheese , Chymosin , Enzymes, Immobilized/chemistry , Paraffin , Renin , RhizomucorABSTRACT
The production of a notable, safe and highly active pectinase by the local fungal strain Trichoderma viride EF-8 utilizing the abundant pigmented Egyptian onion (Allium cepa L.) skins (6.5%, w/v) was achieved in 4 days submerged fermentation (SMF) cultures, at temperature and pH of 30 °C and 4.0, respectively. The indigenously produced pectinase was partially purified by 50% batch ethanol precipitation and its general properties were studied following the standard procedures. The lyophilized enzyme preparation was free of any ochra or aflatoxins. The optimum conditions for the partially purified enzyme form were 2 mg/mL and 1% (w/v) enzyme protein and substrate (citrus pectin) concentrations, reaction pH and temperature of 7.0 and 40 °C, respectively. The results presented the low cost onion skins waste as the major substrate for the fungal pectinase production and its subsequent use in perfect fruit (apple, lemon and orange) juices clarification with remarkable stability during and after this process, which certainly enhance fruit juices processing in the tropics.
ABSTRACT
The Aspergillus niger NRC1ami pectinase was evaluated according to its hydrolysis efficiency of dry untreated orange peels (UOP), HCl-treated orange peels and NaOH-treated orange peels (HOP and NOP). Pectinase was entrapped in polyvinyl alcohol (PVA) sponge and the optimum pH and temperature of the free and immobilized enzymes were shifted from 4, 40 °C to 6, 50 °C respectively. The study of pH stability of free and immobilized pectinase showed that the immobilization process protected the enzyme strongly from severe alkaline pHs. The immobilization process improved the enzyme thermal stability to great instant. The unique feature of the immobilization process is its ability to solve the orange juice haze problem completely. Immobilized enzyme was reused 12 times in orange juice clarification with 9% activity loss from the original activity. Maximum reaction rate (V(max)) and Michaelis-Menten constant (K(m)) of the partially purified form were significantly changed after immobilization.
