Biochemical Role of Yeast Enzymes during Ripening Period in the Egyptian Ras Cheese (Romy)
Hammad, M., El-Kadi, S., Ahmed, G. (2023). Biochemical Role of Yeast Enzymes during Ripening Period in the Egyptian Ras Cheese (Romy). EKB Journal Management System, 2(1), 36-42. doi: 10.21608/djas.2023.405940
Mohamed Hammad; Sherif Mohamed El-Kadi; Gamal Ahmed. "Biochemical Role of Yeast Enzymes during Ripening Period in the Egyptian Ras Cheese (Romy)". EKB Journal Management System, 2, 1, 2023, 36-42. doi: 10.21608/djas.2023.405940
Hammad, M., El-Kadi, S., Ahmed, G. (2023). 'Biochemical Role of Yeast Enzymes during Ripening Period in the Egyptian Ras Cheese (Romy)', EKB Journal Management System, 2(1), pp. 36-42. doi: 10.21608/djas.2023.405940
Hammad, M., El-Kadi, S., Ahmed, G. Biochemical Role of Yeast Enzymes during Ripening Period in the Egyptian Ras Cheese (Romy). EKB Journal Management System, 2023; 2(1): 36-42. doi: 10.21608/djas.2023.405940

Biochemical Role of Yeast Enzymes during Ripening Period in the Egyptian Ras Cheese (Romy)

Damietta Journal of Agricultural Sciences
Volume 2, Issue 1, January 2023, Page 36-42  XML PDF (863.69 K)
Document Type: Original Article
DOI: 10.21608/djas.2023.405940
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Authors
Mohamed Hammad email orcid 1; Sherif Mohamed El-Kadiorcid 2; Gamal Ahmed1
1Food Science Dept., Fac. of Agric., Damietta University, Damietta, Egypt
2Department of Agricultural Biotechnology, Faculty of Agriculture, Damietta University, Egypt
Abstract
These tests consisted of counting, isolation, and identification of the yeasts. The highest value of yeast count in Ras cheese samples was 1095 cfu/g in Fa1 sample which taken from Dakahlia Governorate in fresh samples. The lowest value was 60 cfu/g in Fa2 sample which taken from Kafr El-Sheikh Governorate in Dayer samples. Twenty-five yeast isolates were collecting from the yeasts which grown on Rose Bengal yeast extract sucrose agar medium. The shape of yeast colonies were varied between oval and irregular of colonies, and the appearance of them were glossy and slime. Colonies dimensions were varied between 0.5 and 18 mm. Nine yeasts were identified based on morphological, biochemical, and physiological characteristics in Al-Azhar university represented in the regional center for Mycologyy & Biotechnology and the results were Candida parapilosis, C. lusitanae, Pichia anamola, Hansenula anomala, C. pelliculosa, C. lusitanae, C. famata, C. lipolytica and Debaryomyces hansenii. Enzymes which hydrolysis proteins, lipids, and sugars by yeast during the period of ripening were studied. All yeast species were tested for proteolysis and lipolysis on PDA medium. All yeast strains gave a positive result in sugars hydrolysis and produced acids. Most yeast strains did not give gas in the Durham’s fermentation tube. Finally, the ability of yeast isolates to produce organic acids were tested. All yeast isolates gave fast results and a high concentration for producing lactic and formic acid. It was in a lower concentration in the case of citric, oxalic, and tartaric acid, but acetic acid production was small and at lowest rate.
Keywords
Yeast enzymes; lactose fermentation; organic acids production; proteolysis; Ras cheese and Ripening
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