Investigation of the Lactic Acid Bacteria in Kazak Cheese and Their Contributions to Cheese Fermentation

Abstract

Kazak cheese is a traditional dairy product fermented by lactic acid bacteria (LAB) in Xinjiang. To investigate the LAB in Kazak cheese and their contributions to cheese fermentation, four representative LAB, Streptococcus thermophilus B8, Lactobacillus helveticus B6, Weissella confusa B14, and Lactobacillus rhamnosus B10, were isolated from Kazak cheese and subsequently used to ferment cheeses, which were named StC, LhC, WcC, and LrC, respectively. The result showed that most of the physical and chemical indicators had no significant difference, except for moisture and fat. W. confusa B14 was beneficial to the production of amino acids, whereas S. thermophilus B8 promoted the formation of organic acids and contributed to formation ideal texture property. Furthermore, the four cheeses all possessed a strong fruity aroma, with brandy, sweet, herbaceous, pungent, and fatty aromas being the most prominent in WcC. This is because L. helveticus B6 produced a high concentration of hexanal, nonanal, octanal, 3-methylbutanoic acid, ethyl acetate, ethyl butanoate, isoamyl acetate, and ethyl hexanoate in LhC. Research on the fermentation mechanism of LAB in cheese will provide a theoretical basis for the quality control and industrial production of Kazak cheese.

Evaluation of the Effect of Auxiliary Starter Yeasts With Enzyme Activities on Kazak Cheese Quality and Flavor

“…Volatile aromatic compounds were extracted with an aging DVB/CAR/PDMS fiber (50/30 μm; Agilent Technologies, Palo Alto, CA, United States). The SPME fiber was first desorbed for 5 min in the injection port at 230°C before use to reduce the carryover from the previous analysis, after which the SPME needle was introduced into the septum in the vial cap, and the fibers were exposed to the headspace for 40 min at 40°C to extract volatile compounds ( Li et al, 2020 ; Zheng et al, 2020 ).…”

“…To evaluate which compounds were responsible for the aroma of Kazak cheeses, odor activity values (OAVs) were obtained by dividing the concentration of each compound by the respective odor threshold (in water) reported in the literature for the aroma analysis ( Gemert, 2011 ; Li et al, 2020 ).…”

The Transcriptional Regulatory Network of Corynebacterium pseudotuberculosis

“…Both sigA and sigB were previously associated with virulence in other bacteria; S igA can be specifically required for the expression of virulence genes in M. tuberculosis [ 131 , 137 ]. SigB controls the expression of many genes involved in the virulence of pathogens, such as biofilm formation, cellular differentiation, pathogenesis, stress resistance and sporulation in several bacteria [ 131 , 138 ]. Pacheco et al assessed the role of SigE in C. pseudotuberculosis using a sigE -mutant strain under different stress conditions, including acid stress.…”

Genetic identification of native lactic acid bacteria in raw cow’s milk and artisanal Poro cheese

“…La bacteria de Lactobacillus spp se ha observado en la leche cruda en Pico, Portugal (Domingos-Lopes et al, 2017), y Lb. rhamnosus se han recuperado de leche (Italia) (Innocente et al, 2016), quesos fermentados: Parmesano (Parmigiano Reggiano, Italia) (Sgarbi et al, 2013), Caciocavallo Palermitano (Sicilia, Italia) (Guarrasi et al, 2017) y en el queso artesanal Kazak (Xinjiang, China) (Li et al, 2020 La especie de Lb. rhamnosus recientemente fue renombrada como Lacticaseibacillus rhamnosus.…”

“…Por otro lado, es importante puntualizar que en los quesos, el sabor es desarrollado por diversos compuestos orgánicos antes citados; formados durante la fermentación, cuajado de la leche y en su caso maduración del queso. Estos compuestos varían según las cepas bacterianas nativas presentes o utilizadas para fermentar cada tipo de queso (Li et al, 2020). Así que, es importante el uso de las técnicas de biología molecular como la extracción del ADN genómico, amplificación de un fragmento del gen ARN ribosomal 16S con la ayuda de oligonucleótidos universales por reacción en cadena de la polimerasa (PCR) y posterior secuenciación de las amplificaciones con el método de Sanger, para identificar de forma más precisa las bacterias ácido-lácticas asociadas a los alimentos agropecuarios como la leche bronca y quesos frescos artesanales.…”