تنمية خميرة الخبز على عصير الصبار وتحديد الرقم الهيدروجيني ودرجة الحرارة المناسبين للنمو

Abstract

Aim: This study aims to evaluate the using of Cactus opuntia cladodes (COC) extract medium for growth of Saccharomyces cerevisiae (Baker's Yeast, BY), and to optimize pH and temperature values of the growth. Methodology: The study design was a comparative study. The control media were both potatoes dextrose (PD) agar (PDA) and broth (PDB). The Opuntia plant aged 1-2 years was obtained from a farm located in the border of Jabalia Refugee Camp. The crude COC extract was diluted to 50% before using as experimental medium for BY. The preactivated BY sample was diluted to 10-7 before use. Experiments were carried out on both surface and submerged cultures. SPSS system was used to analyze the obtained data. Results: The results showed that the BY can grow well and proliferate in COC extract (50% dilution) where the average specific growth rate () was about 0.17 h-. Similar to the growth of the BY on PDB medium, optimum pH and optimum temperature values for the yeast growth in the extract medium were 4.0 and 30 0 C, respectively. It was also found that average yeast dry weight which was produced in COC extract was about 41.3 g/L, while an equal quantity of PDB produced about 54.1 g/L at the same conditions. Moreover, the results showed that 1000g fresh weight of COC produced 62.0 g of BY. As a conclusion, COC extract could be used for production of BY at pH 4.0 and 30 0 C.