MICROBIOLOGICAL STUDIES ON THE STORABILIT Y OF RAW THICK JUICE

Raw thick juice from sugar beets must be storable if it is to be proce ssed after the campaign. The storability of raw thick juice is determi ned by the proliferation and metabolism of the microorganisms present in the product. These depend on the water activity (a(w) value), pH an d storage temperature of the raw thick juice, and the number of microo rganisms. Raw thick juice with an a. value exceeding 0.88 (equivalent to less than 67% dry substance by weight) is not storable as a rule. I n storage tests of raw thick juice with a(w) values > 0. 88, a pH of 9 was found better than a pH of 6, and a temperature of 5-degrees-C bet ter than one of 15-20-degrees-C or 30-degrees-C. Osmophilic yeasts are to be regarded as harmful in raw thick juice. They can multiply and, with a starting cell population of 5.10(5) per ml of raw thick juice a t an a. value of 0. 88, pH of 9, and temperature of 15-20-degrees-C, a fter 98 days can caise macroscopic spoilage with foam formation. Raw t hick juice with an a(w) value of less-than-or-equal-to 0.88, pH of 9, and not more than 1.10(3) microorganisms per ml (of which at most 1.10 (2) osmophilic yeasts) was storable for 300 days at 15-20-degrees-C pr ovided the surface was sprayed every 3 weeks with 30 g/m2 of formalin.