Chemical and microbiological characterisation of kefir grains

Abstract

Chemical and microbiological composition of four Argentinean kefir grains from different sources as well as characteristics of the corresponding fermented milk were studied. Kefir grains CIDCA AGK1, AGK2 and AGK4 did not show significant differences in their chemical and microbiological composition. In contrast, protein and yeast content of AGK3 was higher than in the other grains. Although grain microflora comprised lactobacilli, lactococcus, acetic acid bacteria and yeast, we found an important difference regarding species. Lactococcus lactis subsp. lactis, Lactobacillus kefir, Lactobacillus plantarum, Acetobacter and Saccharomyces were present in all types of kefir grain. While Leuconostoc mesenteroides was only isolated from grains CIDCA AGK1 and Lactococcus lactis subsp. lactis biovar diacetylactis, Lactobacillus parakefir and Kluyveromyces marxianus were only isolated from CIDCA AGK2 grains. All grains produced acid products with pH between 3·5 and 4·0. The apparent viscosity of AGK1 fermented milk was greater than the product obtained with AGK4. All fermented milks had inhibitory power towards Escherichia coli but AGK1 and AGK2 supernatants were able to halt the bacterial growth for at least 25 h. Grain weight increment in AGK1, AGK2 and AGK3 during growth in milk did not show significant differences. Despite their fermenting activity, AGK4 grains did not increase their weight.

A review: chemical, microbiological and nutritional characteristics of kefir

“…bulgaricus (Yuksekdag et al 2004b); Lb. parakefir (Garbers, Britz, & Witthuhn, 2004;Garrote, Abraham, & De Antoni, 2001) (Yuksekdag et al, 2004a); Pediococcus acidilactici, P. dextrinicus, P. pentosaceus (Sabir et al, 2010); Acetobacter aceti (Motaghi et al, 1997); A. lovaniensis (Magalhaes et al, 2011a); and A. syzgii (Miguel et al, 2010). Witthuhn et al (2004) reported that LAB and yeast levels present in kefir grains vary widely, ranging from 6.4 × 10 4 to 8.5 × 10 8 and 1.5 × 10 5 to 3.7 × 10 8 cfu/mL, respectively.…”

“…(Witthuhn et al, , 2005; Candida lipolytica, C. holmii ; C. inconspicua, C. maris ; C. kefyr (Motaghi et al, 1997;Witthuhn et al, 2004Witthuhn et al, , 2005; C. lambica, C. krusei, Cryptococcus humicolus (Witthuhn et al, 2005); Kluyveromyces marxianus (Garrote et al, 1998(Garrote et al, , 2001KokTas et al, 2012;Loretan et al, 2003;Simova et al, 2002); Klyveromyces lactis (Loretan et al, 2003;Magalhaes et al, 2011a); Saccharomyces cerevisiae (Garrote, Abraham, & De Antoni, 1997;Loretan et al, 2003;Magalhaes et al, 2011a;Motaghi et al, 1997;Simova et al, 2002;Witthuhn et al, 2004); S. fragilis, S. lactis (Motaghi et al, 1997); S. lipolytic (Garrote et al, 1997); Zygosaccharomyces rouxii, Torulaspora delbrus, Torulaspora delbrueckii, Debaryomyces hansenii (Loretan et al, 2003); Kazachstania aerobia, Lachancea meyersii (Magalhaes et al, 2011a); and Geotrichum candidum (Garrote et al, 1997;Witthuhn et al, 2005). Grønnevik et al (2011) found that the LAB count in kefir samples decreased during the first 4 weeks of storage, whereas yeast levels increased throughout the storage period.…”

"Petit suisse" cheese from kefir: an alternative dessert with microorganisms of probiotic activity

“…Acidity was also a determining variable in the time spent until formation of a stable clot, since the Ministry of Agriculture, Livestock, and Supply -MAPA (2007) establishes values between 0.6 and 2.0 g acid lactic.100 g -1 product for fermented milk, and for kefir it is recommended that acidity does not exceed 1 g lactic acid.100 g -1 product. Therefore, the Quark cheese had developed acidity near the maximum recommended by the MAPA (BRASIL, 2007), and a concentration of lactic acid (9.6 mg.mL -1 ) of about 10 times greater than the concentration (0.95 mg.mL -1 ) of lactic acid capable of neutralizing the action of pathogenic microorganisms, as observed in the studies of Garrote, Abraham and De Antoni (2001).…”

“…However, these proteins can be incorporated into the final product when using ultrafiltration, in which all coagulated milk is converted into cheese (FOX, 2001), a practice widely used on industrial scale in some countries (VEIGA; VIOTTO, 2001). …”

Atividade antiinflamatória de carboidrato produzido por fermentação aquosa de grãos de quefir

“…Alguns microrganismos estão sempre presentes no simbiótico, mas outros nem sempre são encontrados, dependendo do método de cultura e substrato utilizado. 7 Em culturas lácteas encontra-se um polissacarídio conhecido como quefirano, ou como fator de crescimento de quefir -KGF, que constitui um bioproduto carboidratado secretado por algumas bactérias presentes nos grãos de quefir e que permite o encapsulamento de suas cepas microbianas em uma matriz de polissacarídios. É um exopolissacarídio parcialmente solúvel em água, composto de unidades repetitivas de monossacarídios (galactose e glicose), na proporção de 1,1:0,9.…”