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Preparation, Production and Industrial Application of Cheese Protective Cultures
(Izmir Institute of Technology, 2018) Şatana, Elçin; Harsa, Hayriye Şebnem
Cheese industry is always under the risk of microbiological contaminations. These contaminants can be either bacteria or fungal species; both affect the final product quality and acceptance. Globally, 20% of the cheese produced industrially is lost due to microbial contaminations. Fungal contaminations can be overcome by the usage of chemicals; sorbate, benzoate, natamycine, propionate, etc. or by natural biopreservatives such as protective cultures or some metabolites of antifungal cultures. Chemical preservatives have a legal limit for their usage and these limits are generally not effective to prevent the product from fungal growth. Also consumers demand goes toward the clean-labeled products and force the manufacturers to use bioprotectants if necessary. There are many types of bioprotectants commercially available with defined lactic acid bacteria combinations which are not so effective for some fungal species due to the species that they include. In this study, several lactic acid bacteria (LAB) strain has been selected to prepare efficient protective culture combinations e.g. Lactobacillus rhamnosus, Lactobacillus plantarum and Lactobacillus paracasei spp. paracasei. The maximum antifungal effect was determined by using mixed culture combination of lactic acid bacteria strains with equal volume. In cheese applications, 3x108 cfu/ml antifungal bacteria mixture including; Lactobacillus rhamnosus, Lactobacillus plantarum and Lactobacillus paracasei spp. paracasei, was inoculated into the curd before fermentation and found more effective than surface applications to the final products. In yoghurt production, same antifungal lactic acid bacteria mixture was found to be effective when applied before fermentation with 106 cfu/ml initial cell counts.
Adsorptive Characteristics of Aflatoxin B1 in the Presence of Purified Clinoptilolite Rich Mineral and Lactobacillus Plantarum S2
(Izmir Institute of Technology, 2012) Bulut Albayrak, Çisem; Ülkü, Semra
The human diet contains a wide variety of natural carcinogens. Aflatoxin B1 (afB1) is the most toxic and most prevalent compound. Both probiotic lactic acid bacteria and clinoptilolite rich zeolite mineral have potential to eliminate this toxin. This study was planned in order to investigate adsorptive characteristics of afB1 by local purified clinoptilolite rich mineral (PNZ) and probiotic strains which were isolated from different natural sources (fermented cabbage, boza ) in the present work. PNZ and isolated strains were characterized by using several physical, chemical and biological techniques. Adsorption characteristics of both probiotic lactobacilli and PNZ were investigated in simulated gastrointestinal solutions. The chosen probiotic strain was identified as L. plantarum .The studies indicated that, both L. plantarum S2 and PNZ can eliminate afB1 in the phosphate buffer solution. They are more effective when they were used together (45% for L. plantarum S2, 32% for PNZ, 86%for L. plantarum S2 and PNZ together). AfB1 adsorption equilibrium data were best represented by Sips isotherm model for PNZ, whereas by Langmuir isotherm model for L. plantarum S2. Thermodynamic studies implied that afB1 adsorption by mineral and L. plantarum S2 was physical adsorption. Experiments with different temperatures showed that afB1 adsorption by PNZ was exothermic but afB1 adsorption by lactobacilli was endothermic. Adsorption kinetics were analysed by diffusional models and reaction models for afB1 adsorption by PNZ mineral. Both film diffusion and /or intra particle diffusion were effective on adsorption kinetics depending on the experimental conditions (Temperature, pH, agitation speed, etc).

Phd Degree / Doktora

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