Evaluating the effect of probiotic yeast Kluyveromyces marxianus on survival of Penicillium. notatum and Aspergillus. parasiticus in set yoghurt

Abstract

Background: Because high nutritional value and beneficial effects, Yoghurt is one of the functional food and rich in calcium, phosphorus, riboflavin, vitamin B5, B12, nicotinic acid, zinc and magnesium. Despite the high benefits of yoghurt, it has a limited shelf life (between 21 and 28 days) since its high humidity. Because of the production of mycotoxins, Aspergillus and Penicillium species are important. The aim of this study was to evaluation the effect of Kluyveromyces marxianus on the survival of penicillium notatum and Aspergillus parasiticus in probiotic yoghurt during storage time. Materials and methods: In this study, Kluyveromyces marxianus PTCC = 5189 yeast was used to produce probiotic yoghurt. Aspergillus parasiticus PTCC=5018 (IR 63) and penicillium notatum PTCC=5074 were used to induce contamination in the samples. Changes in the number of probiotic yeasts and contaminants during 28 days of storage at 4 °C were evaluated and compared with the control sample. Results: Due to the effect of Kluyveromyces marxianus, the population of yoghurt corruption molds (penicillium notatum and Aspergillus parasiticus), decreased significantly. After 28 days of storage time (P<0.01), the number of Kluyveromyces marxianus was adequate to provide a probiotic product with a 7.35 log CFU/gr (P<0.01), so Kluyveromyces marxianus can be used to production of probiotic yoghurt. The sensory evaluation results showed that plain yoghurt is more acceptable, however it wasn’t significantly (P>0.05). Conclusuion: Due to the ability of Kluyveromyces marxianus to inhibit mold spoilage, as well as the sensory acceptability of probiotic yoguhrt, Kluyveromyces marxianus can be used on an industrial scale to produce probiotic yoghurt.