Heat Resistant Moulds in Pasteurized Fruit Syrups

Fruit syrups or concentrates are sweeteners that are used in food and beverage industry as well as in the pharmaceutical industry. These fruit syrups or juice concentrates are naturally acidic products that are subjected to pasteurization to eliminate the vegetative cells of bacteria, fungi and their less heat resistant spores. There is a chance for heat resistant moulds and Alicyclobacillus spp. to grow in the product after the pasteurization due to the production of heat resistant structures such as ascospores or similar structures and bacterial spores. Byssochlamys, Talaromyces and Neosartorya have been identified frequently as heat resistant moulds in heat processed fruit products. Heat resistant moulds can cause an economical damage to the products by breaking down the texture, producing off flavors, phase separation and causing health hazards due to the ability of mycotoxins formation by some species. In order to detect heat resistant moulds it is necessary to give a selective heat treatment by the laboratory pasteurization to eliminate vegetative cells of bacteria, fungi and less heat resistant fungal spores while stimulation the activation of heat resistant spores formed by heat resistant moulds. Due to the low occurrence of the spores relatively large samples are analyzed. Most of the methods suggest a long incubation period of 30 days to mature the colonies that is too long for quality control measures in food and beverage industry. Impedance monitoring has been suggested as a rapid detection method for the detection of common heat resistant moulds such as Byssochlamys.