FERMENTED DAIRY PRODUCT
The present invention provides a fermented dairy product wherein the acidification rate of a yogurt starter culture and the survival rate of an optionally further present probiotic bacteria are enhanced by the presence of a helper strain. The helper strain is a bacterial strain capable of reducing the redox potential (Eh) of sterilized skim milk to −50 mV or lower (more negative) values upon incubation of sterilized skim milk with said helper strain for 5-24 hours at 25-45° C,. Further advantageously, the inoculation rate of an optional probiotic culture needed for producing the fermented dairy product and comprising desirable levels of viable bifidobacteria—even at the end of its shelf life—is significantly reduced. The fermented dairy product especially relates to a yoghurt-type product.
1 . A method for preparing a fermented dairy product comprising:
(a) providing milk;
(b) providing viable bacteria comprising:
(i) a yogurt starter culture strain,
wherein the yogurt starter culture comprises a strain of Streptococcus thermophilus in combination with a strain of Lactobacillus delbrueckii spp. bulgaricus and/or a strain of Lactobacillus acidophilus , and
(ii) a mesophilic helper bacteria strain,
wherein the helper strain is a Gram positive, non-spore-forming, anaerobic, catalase negative lactococcal strain, which produces lactic acid as an end product of its carbohydrate metabolism; and
wherein the helper bacteria strain is capable of reducing redox potential (Eh) of sterilized skim milk to −50 mV or lower values upon incubation for 5-24 hours at 25-33° C.;
(c) combining the viable bacteria with the milk, thereby providing inoculated milk; and
(d) incubating the inoculated milk at a temperature of 37-45° C. to a pH of 5.0 or lower, thereby obtaining the fermented dairy product.
2 . The method according to claim 1 , wherein the viable bacteria further comprises a probiotic culture comprising one or more strains of Bifidobacterium and Lactobacillus rhamnosus.
3 . The method according to claim 1 , wherein the helper bacteria strain is capable of reducing the redox potential (Eh) of sterilized skim milk to −200 mV or lower values upon incubation for 5-24 hours at 25-33° C.
4 . The method according to claim 1 , wherein the inoculated milk is incubated at a temperature of 42-45° C.
5 . The method according to claim 1 , wherein the helper bacteria strain is not capable of reducing the redox potential (Eh) of sterilized skim milk to −50 mV or more negative values upon incubation of sterilized skim milk with the helper strain for 5 hours at 42° C.
6 . The method according to claim 1 , wherein the helper bacteria strain does not comprise a strain selected from the group consisting of:
Lactococcus lactis DSM21407 or a mutant or a variant thereof,
Lactococcus lactis DSM21406 or a mutant or a variant thereof,
Lactococcus lactis subsp. lactis MCC852 (FERM BP-10742),
Lactococcus lactis subsp. lactis MCC857 (FERM BP-10757),
Lactococcus lactis subsp. lactis MCC859 (FERM BP-10744),
Lactococcus lactis subsp. lactis MCC865 (FERM BP-10745), and
Lactococcus lactis subsp. lactis MCC856 (FERM BP-10746).
7 . A fermented dairy product, comprising viable bacteria comprising:
(a) a yogurt starter culture strain,
wherein the yogurt starter culture comprises a strain of Streptococcus thermophilus in combination with a strain of Lactobacillus delbrueckii spp. bulgaricus and/or a strain of Lactobacillus acidophilus ; and
(b) a mesophilic helper bacteria strain,
wherein the helper strain is a Gram positive, non-spore-forming, anaerobic, catalase negative lactococcal strain, which produces lactic acid as an end product of its carbohydrate metabolism;
wherein the helper bacteria strain is capable of reducing redox potential (Eh) of sterilized skim milk to −50 mV or lower values upon incubation for 5-24 hours at 25-33° C., and
wherein the helper bacteria strain does not comprise a strain selected from the group consisting of:
Lactococcus lactis DSM21407 or a mutant or a variant thereof,
Lactococcus lactis DSM21406 or a mutant or a variant thereof,
Lactococcus lactis subsp. lactis MCC852 (FERM BP-10742),
Lactococcus lactis subsp. lactis MCC857 (FERM BP-10757),
Lactococcus lactis subsp. lactis MCC859 (FERM BP-10744),
Lactococcus lactis subsp. lactis MCC865 (FERM BP-10745), and
Lactococcus lactis subsp. lactis MCC856 (FERM BP-10746).
8 . The fermented dairy product according to claim 7 , wherein the viable bacteria further comprises a probiotic culture comprising one or more strains of Bifidobacterium and Lactobacillus rhamnosus.
9 . The fermented dairy product according to claim 7 , wherein the helper bacteria strain is capable of reducing the redox potential (Eh) of sterilized skim milk to −200 mV or lower values upon incubation for 5-24 hours at 25-33° C.
10 . The fermented dairy product according to claim 7 , wherein the helper bacteria strain is not capable of reducing the redox potential (Eh) of sterilized skim milk to −50 mV or more negative values upon incubation of sterilized skim milk with the helper strain for 5 hours at 42° C.
11 . The fermented dairy product according to claim 7 , wherein the helper bacterial strain comprises a strain of Lactococcus lactis spp. lactis.
12 . The fermented dairy product according to claim 11 , wherein the helper bacterial strain comprises strain CSK 1788 of Lactococcus lactis spp. lactis.
13 . The fermented diary product according to claim 7 , wherein the product is a yogurt.
14 . Yogurt starter culture, comprising
(a) a yogurt starter culture strain,
wherein the yogurt starter culture comprises a strain of Streptococcus thermophilus in combination with a strain of Lactobacillus delbrueckii spp. bulgaricus and/or a strain of Lactobacillus acidophilus , and
(b) a mesophilic helper bacteria strain,
wherein the helper strain is a Gram positive, non-spore-forming, anaerobic, catalase negative lactococcal strain, which produces lactic acid as an end product of its carbohydrate metabolism; and
wherein the helper bacteria strain is capable of reducing redox potential (Eh) of sterilized skim milk to −50 mV or lower values upon incubation for 5-24 hours at 25-33° C.
15 . The yogurt starter culture according to claim 14 , wherein the helper bacteria strain does not comprise a strain selected from the group consisting of:
Lactococcus lactis DSM21407 or a mutant or a variant thereof,
Lactococcus lactis DSM 21406 or a mutant or a variant thereof,
Lactococcus lactis subsp. lactis MCC852 (FERM BP-10742),
Lactococcus lactis subsp. lactis MCC857 (FERM BP-10757),
Lactococcus lactis subsp. lactis MCC859 (FERM BP-10744),
Lactococcus lactis subsp. lactis MCC865 (FERM BP-10745), and
Lactococcus lactis subsp. lactis MCC856 (FERM BP-10746).