A procedure was developed and tested for fermentation of cucumbers at low concentrations of NaCl in experimental, anaerobic tanks. The procedure included washing of the cucumbers, use of a buffered cover brine composed of 0.045M calcium acetate, sodium chloride to equilibrate at 2.7% or 4.6%, Lacrobacillus plantanon culture, and N, purging to remove dissolved C02. The fermentations were predominantly homofermentative, lactic acid accounting for 95% of the cucumber sugars fermented. Firmness retention of the fermented cucumbers during storage for 1 year was improved by heating packaged products to 69°C before storage, but firmness retention was acceptable in unheated products.
The time required to cool size 2B (3.43 to 3.75-cm-diameter) pickling cucumbers by a commercial spray-type hydrocooler to less than 9°C was about 18 min at typical initial fruit temperatures of 25 to 29°C. During this period, the fruit was exposed to the recycled water, which reached relatively high populations of bacteria (106 to 107 colony forming unites [CFU]/g total aerobes and 105 to 106 CFU/g total Enterobacteriaceae) during a typical day's operation. These numbers exceeded those present on the unwashed fruit, depending upon the volume of fruit previously cooled. Residual chlorine dioxide at 1.3 ppm was found to optimally control (2 to 6 log-cycles reduction) the numbers of bacteria. At 0.95 ppm chlorine dioxide, the numbers of bacteria in the water were relatively static, while at 2.8 and 5.1 ppm the odor of chlorine dioxide became excessive. The bacterial populations in/on the cucumbers were not greatly influenced by chlorine dioxide, even at 5.1 ppm. Apparently, microorganisms on or in the fruit were protected from the chlorine dioxide. Thus, the use of chlorine dioxide in hydrocooling water of cucumbers seems to be an effective means of controlling microbial build-up in the water, but has little effect upon microorganisms on or in the fruit.
A fermentor was designed and constructed for study of the physical, microbiological, and chemical changes that occur during the sauerkraut fermentation. The fermentor has some essential features that include restriction in volume of the sauerkraut bed, construction of clear plastic to permit visual determination of liquid-level changes as a result of gas entrapment within the sauerkraut bed, and a gas-lift device for use in nitrogen purging of the fermenting brine. Fermentations exhibited two distinct stages, the first one gaseous and the second non-gaseous. The gaseous stage was characterized by rapid CO(2) and acid production due to growth by hetero-fermentative lactic acid bacteria with resultant gas entrapment within the sauerkraut bed and a rise in liquid level. Also, rapid disappearance of fructose and rapid appearance of mannitol occurred during this stage. The nongaseous stage was characterized by growth of homo-fermentative lactic acid bacteria with little or no CO(2) production and a gradual increase in lactic acid until all fermentable sugars were metabolized. Nitrogen purging appeared to offer several potential advantages, including a means for brine circulation, removal of CO(2) from the brine, and anaerobiosis to ensure retention of ascorbic acid, desirable color, and other oxygen-sensitive traits in sauerkraut.
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