The effects of heating rate (1.0, 1.5, 2.0 and 2.5 ℃/min) and end point temperature (80, 90 and 100 ℃) on the gel characteristics of Beijing duck myosin were studied by circular dichroism (CD) and low-field nuclear magnetic resonance (LF-NMR). The results showed that the α-helix structure of duck myosin was transformed into β-sheet with increasing temperature during the heating process; the proportion of α-helix gradually decreased, while the proportion of β-sheet gradually increased, which promoted the gelation of myosin. Under the traditional hanging oven heating mode, the hardness, strength and free water content of Beijing duck myosin gel were significantly lower at end point temperature of 80 ℃ than at 90 and 100 ℃ (P < 0.05). In the linear heating mode, the gel water-holding capacity (WHC) and strength of myosin decreased with increasing heating rate. Compared with the traditional hanging oven heating mode, the gel WHC increased at heating rates of 1.0 and 1.5 ℃/min, but decreased significantly at 2.5 ℃/min.
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Basic Research
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Open Access
Analysis & Detection
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The four most famous Chinese braised chicken dishes, typical national dishes in China, were analyzed for their free amino acids and 5’-nucleotides, and the equivalent umami concentration (EUC) and taste activity value (TAV) were calculated. Multivariate statistical analyses such as principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and hierarchical cluster analysis (HCA) were used to analyze the taste profiles of the four dishes. The results showed that there were great differences in the content of free amino acids in these dishes, among which Goubangzi smoked chicken had the highest total amino acid content (363.66–396.96 mg/100 g). According to TAV, glutamic acid and monophosphate (IMP) significantly contributed to the umami characteristics of Goubangzi smoked chicken and Daokou braised chicken, respectively. Electronic tongue analysis showed differences in the taste profiles of the four chicken dishes. PCA, PLS-DA and HCA could effectively distinguish these dishes. Their taste was not determined by single amino acids or free amino acids. The balance between umami, sweet and bitter amino acids and their synergistic effect with nucleotides led to differences in the taste characteristics of the braised chicken dishes. Sweetness, salty taste, sour taste, total amino acids, bitterness, glutamic acid, umami taste and umami amino acids, were important variables that influence the differences in the taste characteristics of the four braised chicken dishes.
The eating quality of lamb in pre-rigor, rigor mortis and post-rigor phases was investigated by using consumers’ sensory evaluation to understand the differences of eating quality characteristics of lamb in different postmortem phases under instant boiling, roasting, boiling and stir-frying conditions, which was expected to provide the reference for lamb quality evaluation and high-quality meat production.
The oyster cut, short loin, knuckle and silverside in per-rigor, rigor mortis and post-rigor phases were obtained from small-tail Han sheep (male, 8 months old). The sensory attributes (including tenderness, juiciness, flavor and overall liking) of lamb after instant boiling, roasting, boiling and stir-frying were evaluated by consumers. The MQ4 (Meat Quality, 4 variables) equation and the grades boundaries were determined by linear discriminant analysis, which were used to analyze the preference score and eating quality grade of lamb.
After instant boiling, the short loin and silverside in pre-rigor had higher tenderness, flavor and MQ4 scores than those in rigor mortis and post-rigor phases (P<0.05), while there was no significant difference in consumers’ scores of oyster cut and knuckle in different postmortem phases (P>0.05). After roasting, the oyster cut in per-rigor and the silverside in post-rigor phase had higher tenderness, juiciness, overall liking and MQ4 scores than those in rigor mortis (P<0.05), but there was no significant difference in consumers’ scores of short loin and knuckle in different postmortem phases (P>0.05). After boiling, the juiciness and overall liking scores of knuckle in post-rigor were higher than those in per-rigor and rigor mortis phases (P<0.05), and there was no significant difference in consumers’ scores of oyster cut, short loin and silverside in different postmortem phases (P>0.05). After stir-frying, the tenderness, overall liking and MQ4 scores of oyster cut in pre-rigor and post-rigor were higher than those in rigor mortis, while the tenderness, flavor, overall liking and MQ4 scores of short loin in pre-rigor were higher than those in rigor mortis and post-rigor (P<0.05). There was no significant difference in consumers’ scores of knuckle and silverside in different postmortem phases (P>0.05). The premium quality (4star) and good quality (5star) samples were higher in pre-rigor (5star: 0%-8.33%; 4star: 47.83%-72.22%) and post-rigor (5star: 0%-8.70%: 4star: 52.78%-58.33%). There were no unsatisfactory quality (2star) samples in pre-rigor and post-rigor phases, while 4.17% and 4.35% of the samples in rigor mortis were 2star after roasting and boiling, respectively.
In general, the pre-rigor and post-rigor lamb had a superior eating quality to rigor mortis lamb based on consumers’ sensory evaluation, and the pre-rigor and post-rigor lamb were preferred by Chinese consumers.
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