## 4 Discussion
The reason might be that 1-octene-3-ol (mushroom) is the typical alcohol produced during frying and decomposes in linoleic acid 10-hydroperoxide [36]. It was deduced that 1-octene-3-ol was produced during the frying process of suet. Furan compounds represented a large class of heterocycles formed as intermediates or products in heat-induced reactions and could significantly affect the organoleptic properties of foods [37]. Of the five MRPs, 2-pentylfuran provided the fattiest and fruity flavors. A typical furan produced during frying is 2-pentylfuran, formed when linoleic acid is oxidized by hydroperoxide [38]. The 2-pentylfuran was the most hydrolyzed after four hours, possibly due to hydroperoxide degradation. By the secondary decomposition of lipid oxidation products (such as hexanal and (E,E)-2,4-decadienal), carboxylic acids could be produced [39]. They generally had a bitter, rancid flavor that gave the MRPs a bad flavor, significantly affecting them when hydrolyzed for 2 h. These findings were consistent with some other research [40]. Carboxylic acid concentrations were consistent except for hexanoic acid, which had a fatty odor and was formed by the secondary degradation of hexanal and (E,E)-2,4-decadienal. Increasing hexanoic acid in MRPs B, C, D, and E may be related to the degradation of hexanal and (E,E)-2, 4-decadienal with prolonged hydrolysis time. ROAVs were proposed to describe how volatile compounds contribute to the overall flavor based on their relative concentration, and the content of each volatile component could be calculated without internal standards. The result is more intuitive, and the error of internal standard is also eliminated. Therefore, ROVA is simpler and more convenient than odor activity values (OAVs) [41]. Additionally, the volatile components with ROAVs \(\geq\) 1, such as 2-ethyl-3,5-dimethylpyrazine, played an essential role in the flavor of MRPs. Moreover, the volatile components with 0.1 \(\leq\) ROAVs \(\leq\) 1, such as hexanal, played an important role in flavor modification. However, the volatile components with ROAVs \(\leq\) 0.1 such as (E)-2-undecenal played a weak role in the flavor of MRPs [42]. In the end, the overall flavor of the MRPs results from the interaction of the various volatile components. Due to the higher peak areas and relative content, (E,E)-3,5-ocadien-2-one and ethyl myristate were significant compounds of MRPs. Despite their higher odor threshold, these aroma-active compounds showed low ROAVs. On the other hand,2-ethyl-3,5-dimethylplyrazine and (E,E)-2,4-nonadienal had low relative amounts but had high ROAVs and strong flavor effects because of low thresholds. Therefore, the effect of volatile components on flavor was determined by combining content and threshold, consistent with [PERSON] et al. [16]. This research exhibited that too short or too long hydrolysis times could increase the ROAVs of harmful components and worsen sensory evaluation. Results showed that the sensory evaluation score with DH of 11.93 had the best overall score. MRPs may produce different levels of volatile compounds and different intensities of individual sensory attributes with different DHs, in line with the results of [PERSON] et al. [43]. There is a possibility that different hydrolysis times produce different volatile components, which will affect Maillard reactions and result in different flavors of MRPs. A rough estimate of ROAVs can be obtained by fitting proxy models to the key volatile components with an extension of hydrolysis time; the reason for not choosing 2-ethyl-3,5-dimethylplyrazine was that it was 100 in each group, so the curve simulation must also be a straight line. The CPM performed best because curve fitting required a large amount of data. The CPM could generate a large amount of prediction data from a small amount of experimental data, thus improving accuracy because PCF was based on uniformly distributing known points along two sides of a curve. Its accuracy was lower than CPM.