*3.1. Proximate Composition and Energy Value*

The results of proximate composition and energy value analysis of sausages are listed in Table 2. Significant differences (*p* < 0.05) were observed among the protein, fat, moisture, ash contents, carbohydrate, and energy value between control and fat replacement group (AC25, AC50, AC75, and AC100). The control shown the lowest protein content, close to the 12.73% protein content in model sausages as reported by [24], but lower than the protein content (13.77%) in frankfurters as described by [25]. As the proportion of AC increased, the protein content in the sausages increased by 1.42%–14.31%. These changes were attributed to the protein in AC.

The fat levels in the replacement sausages significantly (*p* < 0.05) decreased by 12.61%–87.56%, compared with those of the control. The fat content of AC100 was similar to those of the sausage with fried *Pleaurotus eryngii* as fat replacements [11], but lower than those of frankfurters with porcine plasma protein hydrolysates and oxidized tannic acid to partially replace pork fat in [25]. It was because the replacement AC is extremely low in fat. The moisture levels of the sausages were significantly (*p* < 0.05) affected by the increase of AC concentration. Compared to the control, the moisture contents of AC25, AC50, AC75, and AC100 increased by 1.62%, 16.74%, 26.08%, and 31.64%, respectively. The reason was that the moisture content of the AC was higher after water treatment.

In terms of ash content, the replacement group was notably (*p* < 0.05) higher than the control. The ash content of sausages was from 3.12% to 3.57%. The consequences were approximate to the value in frankfurters with phenolic compounds in emulsion gel-based delivery systems as animal fat replacers, which was reported by [18], but higher than those in Bologna sausage and Toscana sausage with partial substitution of pork fat with canola oil, as determined by [3] and [26], respectively.

**Table 2.** Proximate composition (%), energy value (kcal/100 g of the product), water activity, pH, cooking loss and water holding capacity of sausages with replacement of pork fat by *Auricularia cornea* (AC).


Notes: Values are given as mean ± standard error. Different letters in the same row indicate significant differences (*p* < 0.05). Control (0%), AC25 (25%), AC50 (50%), AC75 (75%), AC100 (100%) substitution of pork fat by AC, respectively.

> Energy values of the control (261.61 kcal/100 g) was significantly (*p* < 0.05) higher than that of replacement groups, decreasing by 5.76%–56.40%. The energy value of the AC50 were similar with those obtained by [11]—that is 171.8 kcal/100 g of the pork sausages using deep-fried *Pleaurotus eryngii* as replacements for pork fat. The energy level in AC75 and AC100 sausages were lower than those found by [18]—that is 174–196 kcal/100 g of frankfurters with phenolic compounds in emulsion gel-based delivery systems as animal fat replacers, and [27]—that is 146.24–198.47 kcal/100 g of low-fat burger with high betaglucans content and oat-hull-based ingredient as a fat replacer.

### *3.2. Water Activity and pH*

The water activity and pH of cooked sausage samples are shown in Table 2. There were no significant differences (*p* > 0.05) in water activity levels among all the samples, suggesting that AC did not affect the bound water content in the sausages. The consequences were similar to the values in hot-dog style sausages with pork skin-based emulsion gels as animal fat replacers. The authors of [28] also reported that hydrolyzed collagen or pork skin/green banana flour gel used as a fat replacer in frankfurter-type sausages or Bologna sausages did not influence the water activity.

As the proportion of AC increased, the pH of sausages decreased by 0.47%–2.05%. These changes were put down to the lower pH of AC. The pH of the control was approximate to that obtained by [29], and no significant differences (*p* > 0.05) were found among the AC50, AC75, and AC100. This decline trend was approximate to the trend observed by [24] in the sausage with *Lentinula edodes* as the pork lean meat replacer, [11] in pork back sausages with fat replaced by fried *Pleaurotus eryngii*, and [29] in frankfurter-type sausages with hydrolyzed collagen as replacements for fat.
