|Breidt F, - NCSU|
|Crowley K A, - NCSU|
|Fleming H P,|
Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 1, 1994
Publication Date: N/A
Interpretive Summary: Although sauerkraut is a very healthful food, its consumption has been diminishing. Improvement in product quality and uniformity could reverse this trend. We have established a novel approach for controlling the fermentation of cabbage to sauerkraut. The approach involves adding nisin, a natural compound produced by certain bacteria isolated from sauerkraut and other sources, to shredded, salted cabbage. This compound, which is approved for use in some foods, inhibits certain bacteria that could lead to undesirable sauerkraut. Also added is a special culture of a bacterium isolated from sauerkraut that is resistant to nisin and will ferment the cabbage to more predictable and desirable sauerkraut. This approach takes advantage of natural biological systems involved in the sauerkraut fermentation and offers a potential method for producing more desirable and uniform sauerkraut. If the new method can be applied at the commercial level, both cabbage growers and consumers could benefit.
Technical Abstract: A paired starter culture system for sauerkraut fermentation was proposed previously by our laboratory, consisting of a nisin-producing strain of Lactococcus lactis and a nisin-resistant strain of Leuconostoc mesenteroides. Objectives of this study were to determine nisin production and stability by a genetically marked culture of L. lactis NCK400 in brined dcabbage fermentations and to study the effect of purified nisin on the natural microflora in brined cabbage. We found that NCK400 produced up to 700 IU/mL of nisin in brined cabbage within 24 h, but by 72 h nisin activity was no longer detectable. The nisin produced was shown to have an effect on the microflora of the fermentation, however, resulting in a 40% reduction in the population of homofermentative lactic acid bacteria (LAB) at 33 days. Addition of purified nisin to brined cabbage (up to 12,000 IU/mL) resulted in a reduction in the cell counts of LAB, as compared to a non-treated cabbage brine, to the extent that fermentation by Gram-negativ bacteria occurred. Addition of a nisin-resistant L. mesenteroides strain to the nisin-treated cabbage resulted in a heterolactic fermentation by the added culture, with no evidence of a homolactic fermentation for at least 20 days. We concluded that nisin produced in situ or added to brined cabbage can direct the progression of the species in the resultant fermentations by preventing the growth of naturally present LAB.