Frozen starter cultures

Keogh, B. P. 1970. Survival and activity of frozen starter cultures for cheese manufacture. Appl. Microbiol 19, 928-931. 

Costello, P. 1988. The conduct of malolactic fermentation under commercial conditions. II. Use of commercial freeze-dried and frozen starter cultures of Leuconostoc oenos. Tech. Rev. Aust. Wine Res. Inst. 51 9-12. 

Although lactic starter cultures undoubtedly were frozen earlier, research interest in the use of this technique to produce cultures for commercial purposes began during the mid-1950s. Initial attempts involved two approaches (1) inoculation of milk with the desired culture, incubation in the normal manner so that approximately 0.85% lactic acid was produced, cooling the culture, packaging, and then freezing it at approximately — 29°C and (2) inoculation of milk with the desired... 

Salji, J. P. and Kroger, M. (1981). Proteolysis and lipolysis in ripening Cheddar cheese made with conventional bulk starter and with frozen concentrated direct-to-the-vat starter culture. ]. Food Sci. 46,1345-1348. 

To avoid repeated transformations of competent cells and the need for a starter culture, a frozen cell stock can be created after step 1. To do this, combine 250 [A of the starter culture with 250 1 of storage media (LB + kanamycine, 30% glycerol) and store at —80 °C. This can be used to inoculate future 1 1 cultures. 

Growth and Harvesting of Microaloae. Skeletonema costatum starter cultures were obtained from Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine. The culture conditions are described by Polak (11). The cells were harvested when they were 2 or 3 weeks old by continuous centrifugation. The biomass obtained was immediately frozen at -28°C, freeze-dried, flushed with and stored at -28°C in darkness. A total of four batches were grown and used in experiments. 

Starter cultures are mainly applied as liquid cultures with about 10 to 10 ° microorganisms per ml. They are also available in a freeze-dried or deep frozen preparation with the advantage of very simple application. 

Commercial starter cultures are available in both frozen and freeze-dried formats and can be used to directly inoculate the material to be fermented. The use of these types of cultures, referred to as direct vat set (DVS) cultures, has many advantages over the... 

Reduced viability of cryoprotected, frozen concentrated cheese-starter cultures s Tg ... 

In their nationwide survey of over 100 wineries, Fugelsang and Zoeck-lein (1993) report that 43% of respondents used freeze-dried preparations, with an additional 8% using frozen concentrates. Already reactivated liquid cultures were being used by 34% of the winemakers and only 5% developed starters from their own cultures. Since that time, additional producers of freeze-dried cultures have emerged and the numbers of winemakers availing themselves of these more user-friendly sources of inocula has most likely increased. 

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