Changes in the Physical–Chemical Properties and Volatile Flavor Components of Dry-Cured Donkey Leg during Processing

Abstract

In order to explore the quality variation and flavor formation of dry-cured donkey leg, the changes in physical–chemical composition, lipolytic, free amino acids content and volatile flavor compounds were investigated in this study. Six fresh, trimmed hind legs with average weight of 8.12 ± 0.8 kg were taken from male Dezhou donkeys slaughtered at the age of 24 months with the average live weight of 240 kg. The entire processing time was eight months long including six stages, specifically: cooling, salting, air-drying, fermenting and aging. Samples were collected at 0 d, 10 d, 20 d, 30 d, 65 d, 105 d and 165 d of processing. The results showed that the pH value remained stable in the range of 6.2~6.6. The moisture and water activity significantly decreased (p < 0.05) during processing. The chloride content, ash, total volatile basic nitrogen (TVB-N) and peroxide value (POV) significantly increased (p < 0.05), from 0.45% to 12.39%, from 3% to 17%, from 1.43 mg/kg to 8.98 mg/kg and from 1.39 g/100 g to 5.26 g/100 g, respectively. The thiobarbituric acid (TBARS) value reached its highest value of 0.39 mg MDA/kg at the end of the salting stage and then decreased to 0.34 mg MDA/kg. Eighteen free amino acids and fifteen free fatty acids were detected, and their contents were significantly increased during processing (p < 0.05). Volatile compounds were analyzed using solid-phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS). Among 114 volatile compounds detected in dry-cured donkey leg, aldehydes, esters, alkane and alcohols were more abundant in the final products, with relative concentrations of 41.88%, 5.72%, 5.35% and 5.25%, respectively. Processing significantly affected the physical–chemical properties, which could contribute to the formation of flavor substances of dry-cured donkey leg.

Flavor Improvement of Maillard Reaction Intermediates Derived from Enzymatic Hydrolysates of Oudemansiella raphanipes Mushroom

“…It could be seen from the green frame in Figure 4 D that the content of heptaldehyde and 2-methylbutyraldehyde in MRPs was higher than that of EH, providing a fruity and clear fragrance. In addition, the content of nonanal was increased to amplify the grease taste, which might be attributed to the hydrolysis of free fatty acids, especially from the n-6 and n-9 polyunsaturated fatty acids [ 29 , 30 ]. As can be seen from the red frame in Figure 4 D, as the reaction progressed, the content of 1-octen-3-ol, benzaldehyde, and valeraldehyde in MRIs was decreased, among which 1-octen-3-ol was a secondary hydroperoxide of fatty acids with a unique mushroom aroma, whereas benzaldehyde and valeraldehyde provided an almond flavor [ 31 ].…”

Seasonal Monitoring of Volatiles and Antioxidant Activity of Brown Alga Cladostephus spongiosus

“…Other abundant hydrocarbons were pentadec-1-ene and heptadecane. Hydrocarbons are likely formed as oxidative degradation products of lipids [17]. Aliphatic alcohols were present with high percentages in all months studied, especially when extracted with the fibre f2 (Figure 2), and they were more abundant in the fresh samples.…”

“…Other abundant hydrocarbons were pentadec-1-ene and heptadecane. Hydrocarbons are likely formed as oxidative degradation products of lipids [17].…”

Green Processing Technology of Meat and Meat Products

“…The addition of halogen and spicy flavors showed a positive effect for the relative content of alkanes and ketones during the processing of a Midu pork roll [ 15 ]. Zhang et al [ 16 ] characterized the effect of processing stage on the physicochemical properties and volatile flavor components of dry-cured donkey leg, and demonstrated that aldehydes, esters, alkanes, and alcohols were more abundant in the final products. Wang et al [ 17 ] demonstrated that ultrasound combined with sous-vide cooking was closely related to the improvements in the textural quality of spiced beef.…”