摘要
为研究反复冻融对水产品品质的影响,通过理化方法检测了不同冻融次数处理对大黄鱼解冻损失、p H值、色泽、硫代巴比妥酸值、羰基含量等指标的影响,并采用前表面荧光光谱结合主成分分析(principal component analysis,PCA)和Fisher线性判别分析法(Fisher linear discriminant analysis,FLDA)对不同冻融次数的大黄鱼进行区分。结果显示随着冻融次数增加,大黄鱼的解冻损失显著增加(P<0.05);p H值呈先上升后下降的趋势;L*(亮度)值、b*(黄度)值均有不同程度的增加(P<0.05),a*(红度)值下降(P<0.05);羰基含量和硫代巴比妥酸反应物值(thiobarbituric acid reactive substances,TBARS)增加(P<0.05),反复冻融导致大黄鱼的品质下降。色氨酸和烟酰胺腺嘌呤二核苷酸磷酸(nicotinamide adenine dinucleotide,NADH)的荧光光谱分别结合PCA和FLDA对不同冻融处理组进行分析,结果表明FLDA识别效果优于PCA。通过FLDA建立了新鲜大黄鱼与冻融大黄鱼荧光光谱判别模型,发现色氨酸原始判别的准确率和交叉验证的准确率分别为68.3%和66.7%,NADH原始判别的准确率和交叉验证的准确率均达到100%。由此可见,利用NADH荧光光谱结合化学计量分析可以鉴别不同冻融处理的大黄鱼。研究结果为水产品新鲜度的快速评价提供参考。
The aim of this study was to investigate the effects of freeze-thaw cycles on the quality of large yellow croaker by physico-chemical method and evaluate a rapid method that was based on front-face fluorescence spectroscopy（FFFS） and used to differentiate between fresh and frozen-thawed samples. The pH value, thawing loss, color parameters, thiobarbituric acid reactive substances（TBARS）, and carbonyl content of large yellow croaker muscle were measured after the treatment of different freeze-thaw cycles（0, 1, 3, 5 and 7 times）. The results showed the thawing loss of the fish flesh increased significantly（P0.05） and the pH value showed a trend of first increasing and then decreasing（P0.05） as the number of freeze-thaw cycles increased. Freeze-thaw cycles provoked a decrease（P0.05） in CIE a＊, and an increase（P0.05） in CIE L＊ and CIE b＊. According to the TBARS values and carbonyl content determined, lipid and protein were oxidized significantly（P0.05）. The above results indicated that the repeated freeze-thaw cycles during storage had a detrimental effect on the qualities of large yellow croaker. The fluorescence emission spectra of tryptophan residues（excitation： 290 nm; emission： 305-400 nm） of proteins and nicotinamide adenine dinucleotide（NADH）（excitation： 336 nm; emission： 360-600 nm） were adopted on treated samples. The tryptophan residues fluorescence emission spectra recorded following excitation at 290 nm showed similar shapes among samples with a maximum at about 330 nm. The NADH emission spectra（excitation 340 nm） of all fish samples showed a difference at 465 nm between fresh and frozen-thawed samples. Principle component analysis（PCA） method was applied to tryptophan residues and NADH fluorescence spectral data sets. The first 2 factors of tryptophan residues fluorescence spectra explained 97% of the total variance and the first 3 factors of NADH fluorescence spectra explained 93% of the total variance. PCA results showed a good discrimination between fresh and frozen-thawed fish samples. However, fluorescence spectroscopy combined with PCA could not discriminate clearly between fish samples which had been treated under different freeze-thaw cycles. Fisher linear discriminant analysis（FLDA） method was performed on the 2 data sets. The first 2 functions of tryptophan residues and NADH fluorescence spectra allowed to explain 98.5%（function1 95.7% and function2 2.8%） and 90%（function1 55.5% and function2 34.5%） of variance, respectively. From the NADH spectra, FLDA gave a better distinction between fresh and frozen-thawed fish samples than PCA. Separation between the frozen-thawed samples depending on freezing cycles was observed from the similarity map determined by discriminant factors. Discriminant model of fresh and frozen-thawed large yellow croaker was set up through FLDA. Considering tryptophan fluorescence spectra, correct distinction of 68.3% and 66.7% was observed respectively for the original and cross validation spectra. A better classification was obtained from NADH fluorescence spectra since 100% correct classifications were obtained for the original and cross validation spectra. It is concluded that NADH fluorescence spectra may be considered as a promising method for the reliable differentiation between frozen-thawed and fresh fish. Our results show that front-face fluorescence spectroscopy coupled with chemometric methods has great potential in the development of rapid and non-destructive methods for the freshness evaluation of aquatic products.
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2016年第16期279-285,共7页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金31271890)
浙江省教育厅中青年学科带头人学术攀登项目(pd2013100)
宁波农业重大择优委托项目(2012C10024)
关键词
光谱分析
主成分分析
模型
大黄鱼
冻融次数
荧光光谱
理化特性
鲜度
spectrum analysis
principle component analysis
models
large yellow croaker（Larimichthys crocea）
freeze-thaw cycles
front-face fluorescence spectroscopy
physico-chemical characteristics
freshness
