# Effect of Lentinan on Lipid Oxidation and Quality Change in Goose Meathalls during Cold Storage
## 3 Results and Discussion
### Changes in Flavor Substances  
A SPME-GC-MS method was used to extract and detect the volatile substances of goose meatballs with different contents of LNT during different storage times. The Heat map was used to show the changes in volatile flavor substance contents in goose meatballs with different LNT concentrations during storage (Figure 5). There were 92 substances preliminarily identified from different groups of goose meatballs, including 5 aldehydes, 61 hydrocarbons, 3 ketones, 9 alcohols, 3 ethers and 11 others. Table 3 statistically analyzes the types and quantities of compounds identified in different groups of goose meatball samples. According to the statistical results, the addition of LNT did not change the total amount of volatile substance in goose meatballs in 3-day storage. However, during 7 and 12 days of storage, the total amount of volatile substances changed in different treatment groups, especially at day 12, there was a difference of 10 substances between the 0.5% LNT and 4% LNT groups. This may because the formation of these volatile compounds was related to the degradation of lipids and proteins through non-enzymatic and enzymatic reactions [52]. Table 4 statistically analyzes the percentage of identified compounds in goose meatball samples with different LNT concentrations during storage. Aldehydes make a great contribution to meat flavor because of its strong volatility and low threshold, but a higher content will bring a negative effect on meat flavor [53]. Among aldehydes, the components with high relative content are hexanal and nonanal. Aldehydes are produced by the oxidation of unsaturated fatty acids, which usually represents the degree of fat oxidation [54]. With the addition of LNT, the content of aldehydes decreased (\(p\leq 0.05\)), especially with high concentrations of LNT (4% LNT). There were no aldehydes detected in the 4% LNT samples during storage, indicating that LNT could effectively inhibit fat oxidation, and also had a positive effect on the flavor of goose meatballs. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & **Times/d** & **0\%** & **0.5\%** & **1\%** & **2\%** & **4\%** \\ \hline  & 3 & 3 & 4 & 3 & 2 & 0 \\ aldehydes & 7 & 3 & 3 & 1 & 1 & 0 \\  & 12 & 2 & 2 & 2 & 0 & 0 \\  & 3 & 18 & 17 & 19 & 20 & 21 \\ hydrocarbons & 7 & 18 & 16 & 20 & 20 & 21 \\  & 12 & 20 & 15 & 17 & 21 & 24 \\  & 3 & 2 & 2 & 2 & 2 & 3 \\ ketones & 7 & 2 & 2 & 2 & 2 & 2 \\  & 12 & 2 & 2 & 2 & 2 & 2 \\  & 3 & 4 & 4 & 4 & 3 & 2 \\ alcohols & 7 & 5 & 5 & 6 & 4 & 3 \\  & 12 & 4 & 3 & 3 & 4 & 4 \\  & 3 & 2 & 2 & 2 & 2 & 2 \\ ethers & 7 & 2 & 2 & 2 & 2 & 2 \\  & 12 & 2 & 2 & 2 & 2 & 2 \\  & 3 & 1 & 1 & 0 & 1 & 1 \\ others & 7 & 1 & 0 & 1 & 0 & 1 \\  & 12 & 2 & 1 & 1 & 2 & 3 \\  & 3 & 30 & 30 & 30 & 30 & 29 \\ total & 7 & 31 & 28 & 32 & 29 & 30 \\  & 12 & 32 & 25 & 27 & 31 & 35 \\ \hline \end{tabular}
\end{table} 
Table 3: Effects of LNT content and storage time on substance types of goose meatballs during cold storage (4 °C). Figure 5: Heatmap display of goose meatballs measured by GC-MS. The threshold of hydrocarbons is high, and individual hydrocarbon has little contribution to meat flavor [55]. However, the synergistic effect of various alkanes and olefins may produce a change in meat flavor. In this study, three kinds of ketones were detected, L-Fenchone, (+)-2-Bornanone and 1-(2,3-Dimethylphenyl) ethenone. There was no change in ketones content in both 0.5% LNT and 1% LNT groups (\(p\geq 0.05\)), but an increase in ketones was found in 2% and 4% groups (\(p\leq 0.05\)) compared with LNT-free samples after 3 days. However, when the samples were stored for 7 and 12 days, the effect of LNT on ketones content was negligible compared with LNT-free sample. This may because ketones are generally considered to be by-products formed during the degradation of alkanes and the dehydrogenation of secondary alcohols [56]. The relative content of ketones in goose meatballs is low, therefore their contribution to the flavor of goose meatballs is not prominent.