## 3 Results and Discussions
### Nutritional Properties  
The crude fat, water-soluble proteins, and soluble solids were used to evaluate the nutritional properties of Zhayu samples. The contents of these are illustrated in Figure 3d-f. It was shown that the effects of LAB-inoculated fermentation on the nutritional properties of Zhayu depended on the LAB species and concentrations. When the inoculation amounts were 10\({}^{6}\) cfu/100 g and 10\({}^{7}\) cfu/100 g, the addition of LAB did not significantly affect  
Figure 3: The pH values **(a)**, TA contents **(b)**, TVB-N contents **(c)**, crude fat contents **(d)**, water-soluble protein contents **(e)**, and soluble solid contents **(f)** of Zhayu products prepared by spontaneous fermentation (control) and fermented with _L. plantarum_ (L.P.), _P. acidilactici_ (P.A.), and _P. pentosacous_ (P.P.) at different inoculation amounts. Different letters on the bar denote significant differences (\(p<\) 0.05).  
the contents of crude fat in the Zhayu products (\(p>0.05\)). However, the contents of crude fat noticeably increased in the samples fermented with \(10^{9}\) cfu/100 g of \(L\). _plantarum_ and _P. acidilactici_, or with more than \(10^{8}\) cfu/100g of _P. pentosaceus_. LAB could produce intracellular lipase and extracellular lipase during fermentation, which could promote the degradation of lipids and increase the content of crude fat in fermented products [36]. However, the lipolysis ability of LAB was relatively weak [37]. Thus, only high amounts of LAB addition could affect the contents of crude fat in fermented fish products.  
During fermentation, proteins in fish products were hydrolyzed by endogenous and microbial proteolytic enzymes to form more water-soluble proteins with low molecular weight, which were easily digested and absorbed [5]. However, due to the weak proteolytic activity of LAB, proteins in the LAB-inoculated Zhayu samples could be mainly hydrolyzed by endogenous enzymes such as cathepsins [15; 37]. When the inoculation amount increased over \(10^{8}\) cfu/100 g for _P. acidilactici_ and _P. pentosaceus_, and the amount increased to \(10^{9}\) cfu/100 g for _L. plantarum_, the water-soluble protein content in Zhayu products noticeably increased (\(p<0.05\)) compared with the control. Additionally, the content of water-soluble proteins was the highest in the sample prepared with \(10^{9}\) cfu/100 g _P. pentosaceus_. In other fermented products, it was also found that starter culture showed a pronounced effect on protein degradation [7; 32]. This suggests that the decrease in the pH value after fermentation with LAB promotes the activity of endogenous protease and then increases the content of water-soluble proteins [15].  
The soluble solids in fermented fish products mainly include soluble sugar, vitamins, and minerals. Figure 3f shows that the addition of _L. plantarum_ and _P. acidilactici_ increased the content of soluble solids in fermented Zhayu products, while the soluble solids content of the samples fermented with _P. pentosaceus_ showed a decrease compared with the control. During fermentation, the metabolism of microorganisms promotes the dissolution of soluble solids in cells, but the metabolism also consumes the soluble solids.