*3.2. Substrate Protein, Ash and Crude Lipids Concentration*

In Table 1, the protein, crude lipid, and ash percentages at different fermentation times are reported. All statistical evaluations were performed at α = 0.05.


**Table 1.** Protein, crude lipid, and ash percentages, after different fermentation times.

Bold values are significant at *p* < 0.05. A and B indicate homogeneous groups at α = 0.05: fermentation times that do not differ from each other are designated by the same letter.

The substrate's initial protein content was 11.68 ± 0.48%. It increased slowly by 72 h, reaching up to 32.09 ± 0.77%. The highest protein percentage in the substrate, 48.55 ± 1.15%, was reached after 96 h. This value remained stable until the end of the fermentative process, allowing to obtain a substrate rich in protein, achieving a suitable percentage for aquafeed formulation according to Nasseri et al. [34]. The protein content against the CFU of the yeast and LAB is reported in Figure 2.

of the yeast and LAB is reported in Figure 2.

**Figure 2.** *Lactobacillus reuteri* (circle), *Saccharomyces cerevisiae* (diamond), reported as colony-forming unit (CFU) per g, and protein (bars) levels increasing during the fermentation process, reported as percentages. **Figure 2.** *Lactobacillus reuteri* (circle), *Saccharomyces cerevisiae* (diamond), reported as colony-forming unit (CFU) per g, and protein (bars) levels increasing during the fermentation process, reported as percentages.

during the process, up to 48.55%, making these wastes an excellent raw material for

In Table 1, the protein, crude lipid, and ash percentages at different fermentation

 **Protein % Crude Lipid % Ash %**  H statistic 16.290 7.058 13.386 Asymp. Sign. **0.006** 0.0216 **0.020**  0 h Mean ± S.D. 11.68 ± 0.48 (A) 13.74 ± 0.72 (A) 0.83 ± 0.04 (A) 24 h Mean ± S.D. 15.46 ± 0.40 (A) 14.04 ± 0.74 (A) 0.82 ± 0.04 (A) 48 h Mean ± S.D. 20.01 ± 0.26 (A) 14.65 ± 0.77 (A) 0.78 ± 0.04 (AB) 72 h Mean ± S.D. 32.09 ± 0.77 (B) 14.85 ± 0.78 (A) 0.71 ± 0.04 (AB) 96 h Mean ± S.D. 48.55 ± 1.15 (B) 15.05 ± 0.79 (A) 0.66 ± 0.03 (B) 120 h Mean ± S.D. 48.55 ± 1.15 (B) 15.25 ± 0.80 (A) 0.66 ± 0.03 (B)

The substrate's initial protein content was 11.68 ± 0.48%. It increased slowly by 72 h, reaching up to 32.09 ± 0.77%. The highest protein percentage in the substrate, 48.55 ± 1.15%, was reached after 96 h. This value remained stable until the end of the fermentative process, allowing to obtain a substrate rich in protein, achieving a suitable percentage for aquafeed formulation according to Nasseri et al. [34]. The protein content against the CFU

aquafeed production with *Lactobacillus reuteri* and *Saccharomyces cerevisiae*.

times are reported. All statistical evaluations were performed at α = 0.05.

**Table 1.** Protein, crude lipid, and ash percentages, after different fermentation times.

Bold values are significant at *p* < 0.05. A and B indicate homogeneous groups at α = 0.05: fermentation times that do not differ from each other are designated by the same letter.

*3.2. Substrate Protein, Ash and Crude Lipids Concentration* 

During all fermentations, ash concentrations decreased significantly, from 0.83 ± 0.04% to 0.66 ± 0.03%. This could be due to partial ash utilization by the yeast as a source of minerals [40]. During all fermentations, ash concentrations decreased significantly, from 0.83 ± 0.04% to 0.66 ± 0.03%. This could be due to partial ash utilization by the yeast as a source of minerals [40].

The crude lipid content calculated on the initial substrate was 13.74 ± 0.72%. Throughout the process, this value did not increase significantly; at the end of the fermentation period, it reached just 15.25 ± 0.80%. The crude lipid content calculated on the initial substrate was 13.74 ± 0.72%. Throughout the process, this value did not increase significantly; at the end of the fermentation period, it reached just 15.25 ± 0.80%.

According to the literature [8,35,41], final protein and lipid contents had reached adequate levels in the resulting aquafeed, offering a way to ameliorate the problem of a According to the literature [8,35,41], final protein and lipid contents had reached adequate levels in the resulting aquafeed, offering a way to ameliorate the problem of a lack of protein sources in aquaculture by encouraging the conversion of fish waste into feed, using a low-cost process such as lactic fermentation.
