Effect of co-fermentation system with isolated new yeasts on soymilk: microbiological, physicochemical, rheological, aromatic, and sensory characterizations.

The beany flavor adversely influences consumer acceptance of soymilk (SM) products. Thus, in this work, the co-fermentation of isolated new yeasts (Kluyveromyces marxianus SP-1, Candida ethanolica ATW-1, and Pichia amenthionina Y) and Kluyveromyces marxianus K (a commercial yeast) along with an XPL-1 starter (including five strains of lactic acid bacteria (LAB)) was utilized to mend the beany flavor of fermented SM (FSM) beverages. Probiotic count, pH, titratable acidity, syneresis, water holding capacity, rheological characteristics, and sensory attributes were investigated. Furthermore, the free amino acids, nucleotides, and volatile compounds (VCs) were analyzed, also presenting the collected VC data by exploiting a principal component analysis (PCA) and a heatmap with a hierarchical cluster analysis. The co-fermentation with Kluyveromyces marxianus SP-1 and K remarkably enhanced the LAB strain growth and acid production, improving the rheological attributes, whereas that of yeast along with XPL-1 as a mullite starter could reduce the beany odor. PCA chart displayed that higher amounts of alcohols, ketones, acids, and esters that significantly improved the flavor quality of FSM beverages were generated throughout the co-fermentation process. The co-fermentation with Pichia amenthionina Y generated the highest acetoin (36.19%) and diacetyl (2.02%), thus improving the overall acceptance of FSM, as well as the sensory characteristics of FSM beverages with the highest umami, sweet, odorless amino acids, and umami nucleotides, and the lowest content of alcohol and inosine. Taken together, the co-fermentation of Pichia amenthionina Y along with XPL-1 within SM provides novel insights regarding the development of FSM and fermented beverages.

A Comparative Study of Milk Fat Extracted from the Milk of Different Goat Breeds in China: Fatty Acids, Triacylglycerols and Thermal and Spectroscopic Characterization.

Goat milk (GM) is an excellent alternative to cow milk and has recently been used in commercial infant formula preparation due to its superior fat composition. Here, the fatty acid (FA) composition, triacylglycerol (TAG) molecular species, thermal behavior and infrared spectra of extracted milk fat from the milk of the two main breeds of dairy goat bred in China (Guanzhong GM (GZG) and Xinong Saanen GM (XSG)) are investigated. Gas chromatography, Fourier-transform infrared spectroscopy, differential scanning calorimetry and ultra-performance convergence chromatography with quadrupole time-of-flight mass spectrometry are applied. The obtained results evidence significant fat compositional differences based on the breed that produced the considered GM. The major FAs in both GM fats were capric (C10:0), myristic (C14:0), palmitic (C16:0), stearic (C18:0) and oleic (C18:1 n-9c). GZG presented a higher content of medium-chain saturated FAs, while XSG had higher unsaturated FAs with higher ratios of L/Ln and n-6/n-3. A total of 339 and 359 TAGs were detected and quantified in GZG and XSG, and the major TAGs were those of m/z 740.6712 (14.10 ± 0.27%) and m/z 684.6094 (10.94 ± 0.02%), respectively. Milk TAGs of GZG and XSG showed 24-54 and 26-54 total acyl carbon numbers with a 0-4 and 0-5 double bond number at 68 and 72 various retention times, respectively. Thermal analysis showed that all GM fat samples melted below normal body temperature. Infrared spectra revealed higher absorption values of GZG milk fat. This study provides valuable information to the dairy industry sector about GM fat produced in China, assessing the appropriateness of Chinese GM fat to be applied in Chinese infant formula.