Beet juice can be substrate for producing non-dairy-based probiotic.

Probiotic bacteria can colonize and proliferate in the intestinal tract of humans to prevent the growth of intestinal pathogens. Lactic acid bacteria have been added to a variety of dairy-based products for their probiotic health benefits.

But consumer demand for non-dairy-based probiotic products has increased. So Cornell University scientists wanted to determine the suitability of beet juice as a substrate for making a non-dairy-based probiotic product by lactic acid fermentation. They found that beet juice could serve as a substrate for the production of a non-dairy-based probiotic that has a pH of less than 4.5 and which contains a significant number of viable beneficial lactic acid bacteria.

The scientists squeezed beet juice using a commercial press. Four lactic acid cultures, Lactobacillus acidophilus LA39, L. casei A4, L. delbrueckii D7 and L. plantarum C3, were used in their experiments. Probiotication of beet juice was carried out in test tubes, each containing 15 mL of sterile beet juice. The juice was inoculated with a 24-hour-old inoculum and incubated at 30 C.

Lactic acid was measured by titrating the samples with 0.1 N NaOH to pH 8.2. Sugar was analyzed using the phenol-sulfuric acid method. The researchers determined the number of colony-forming units (CFUs) by using the standard plating technique with MRS agar.

All four lactic cultures were capable of rapidly utilizing beet juice for cell synthesis and lactic acid production without the need for additional nutrients. The log viable cell counts (CFU per mL) reached greater than 9 after 48 hours of growth at 30 C. However, only L. acidophilus and L. plantarum reduced the pH from an initial value of 6.3 to less than 4.5.

Extending the fermentation time beyond 48 hours did not yield a significant increase in the population of viable cells. The lactic cultures did not lose their viability at 4 C for several weeks.

Further information. Yong Hang, Cornell University, New York State Agricultural Experiment Station, 222 Food Research Laboratory, 630 W. North St., Geneva, NY 14456; phone: 315-787-2265; email: ydh1@cornell.edu.