Nondestructive determination of herbicide-resistant genetically modified soybean seeds using near-infrared reflectance spectroscopy

The objective of this study was to evaluate the potential of near-infrared reflectance spectroscopy (NIRS) to differentiate the herbicide-resistant genetically modified (GM) and non-GM soybean seeds. Principal component analysis (PCA) and partial least squares discriminant analysis (PLSDA) were used to classify soybeans with different genes into two groups: genetically modified organisms (GMO) and non-GMO. Calibrations were developed using PLSDA regression with cross-validation. Differences between GM and non-GM soybeans do exist, and excellent classification can be obtained after optimising spectral pretreatment. The PLSDA model using the second derivative pretreatment of the raw spectra had the best calibration and prediction abilities, with 97% accuracy. The results of the present study show that NIRS, together with chemometrics techniques, can be used to identify GM soybeans, thus circumventing time-consuming, costly and laborious chemical and sensory analyses.     

农作物品质的近红外光谱无损检测研究进展

简述近红外光谱分析原理及过程,归纳总结该技术在谷类作物、豆类作物、油料作物以及糖料作物品质检测中的应用,提出存在的问题,指出进一步的研究方向.     

Antioxidant activity of protein hydrolysates derived from threadfin bream surimi byproducts

Antioxidant activities of protein hydrolysates from threadfin bream surimi wastes, including frame, bone and skin (FBS) and refiner discharge (RD), were investigated. FBS and RD were rich in Lys, Glu, Gly, Pro, Asp, Leu, His, Tyr and Phe. FBS was hydrolysed to a greater extent than RD regardless of proteinases tested (Virgibacillus sp. SK33 proteinase, Alcalase, pepsin and trypsin). Pepsin-hydrolysed FBS, at a 5% degree of hydrolysis (DH), showed the highest antioxidant activity based on 2,2′-azinobis (3-ethyl-benzothiazoline-6-sulphonate) (ABTS) radical (0.455 ± 0.054 mg Trolox equivalents/mg leucine equivalents), ferric reducing antioxidant power (FRAP) (0.221 ± 0.005 mM Trolox equivalents) and inhibition of β-carotene bleaching assays. FBS hydrolysates showed higher antioxidant activity based on chemical assays than their RD counterparts. However, FBS and RD hydrolysates protected HepG2 cells against tert-butyl hydroperoxide-induced oxidative damage to a similar extent. Therefore, FBS and RD hydrolysates have a potential as antioxidative neutraceutical ingredients.     

北虫草中虫草素的NIR快速定量测定

应用近红外光谱(NIR)和偏最小二乘法(PLS),建立了北虫草中虫草素的定量分析校正模型。分别采集北虫草子实体的近红外光谱图,应用TQ化学计量学分析软件,对不同化学计量学处理方法进行了比较,并对光谱区域,光谱预处理方法,主成分因子数进行筛选。依据预测效果确定了最佳的校正模型,虫草素含量的预测结果与HPLC检测结果的相关系数为0.9919,校正模型的定标均方差(RMSEC)为102 mg/kg、预测均方差(RMSEP)为281 mg/kg。本方法操作简便,快速无损,可用于北虫草中虫草素含量的快速检测。      

Physicochemical characteristics,protein hydrolysis,and textual properties of surimi during fermentation with Actinomucor elegans

Solid-fermentation is a promising way of producing novel surimi-based food. In the present study, changes in physicochemical characteristics, protein hydrolysis, and textual properties of surimi during the fermentation, including pehtze preparation, salting, and ripening stages, were studied. The protease produced by Actinomucor elegans led to continuous hydrolysis of surimi protein, reflected from the high value of protease activity which reached 69.34 U/g after pehtze preparation stage, the decrease of protein bands intensity in sodium dodecyl sulfate polyacrylamide gel electrophoresis image especially for bands of 200, 43, and 36 KDa, and the increasing contents of free amino acids and trichloroacetic acid-soluble nitrogen. Hardness, springiness, and cohesiveness of the surimi all decreased during pehtze preparation stage, increased after salting, and decreased again after ripening, while adhesiveness kept increasing until the ripening stage started. Scanning electron microscopy images showed a dense and soft microstructure of surimi after ripening. The final surimi product showed high overall acceptability and no Enterobacteriaceae was detected.     

番茄总糖含量的近红外光谱无损检测方法研究

根据偏最小二乘法建立番茄总糖含量的定量分析模型,比较原始光谱和平均光谱以及10 种光谱预处理方法对近红外光谱无损检测番茄总糖含量的影响。结果表明：平均光谱所建立的偏最小二乘法校正模型明显优于原始光谱所建模型,常数偏移消除最适合番茄总糖近红外光谱的预处理,其在11998.9～7497.9cm-1 和4601.3～4256.5cm-1优化光谱区内,所建偏最小二乘法定量分析模型的预测值和实测值的相关系数(R)为0.917,校正标准差(RMSEC)为0.263%,预测标准差(RMSEP)为0.236%。平均光谱和优化的光谱预处理方法可有效提高近红外光谱无损检测番茄总糖含量的准确性。     

Effect of reducing agents on physicochemical properties and gel-forming ability of surimi produced from frozen fish

Effects of different reducing agents (cysteine, ascorbic acid and sodium bisulfite) at various levels on physicochemical properties of protein, transglutaminase activity and gel properties of surimi produced from frozen croaker, lizardfish, threadfin bream and bigeye snapper were studied. Addition of cysteine resulted in the highest increase in the breaking force and the deformation of surimi gels, compared with other reducing agents. The optimum levels of cysteine were 0.05, 0.1, 0.05 and 0.1% (w/w) for surimi from frozen croaker, lizardfish, threadfin bream and bigeye snapper, respectively. Surimi from frozen croaker with cysteine added showed a similar breaking force and deformation to that produced from fresh fish. With addition of cysteine, an increase in sulfhydryl content with a concomitant decrease in disulfide bond content was generally observed. Ca²⁺ ATPase activity also increased, indicating the renaturation of the myosin molecule. T_max of peak 1 (myosin peak) of all surimi sols in the presence of cysteine was shifted to higher temperature. The increased transglutaminase activity was observed with addition of cysteine. Therefore, reducing agents, especially cysteine, recovered the denatured muscle proteins and activated the transglutaminase in the muscle, leading to the increased gel-forming ability of surimi produced from frozen fish.     

Nondestructive evaluation of jujube quality by visible and near-infrared spectroscopy

This study compared prediction ability of interactance, transmission measurements of visible and near-infrared (Vis/NIR) spectroscopy in detecting the soluble solids content (SSC) of jujubes. Calibration models relating Vis/NIR spectra to SSC were developed based on partial least squares regression (PLSR) with respect to the logarithms of the reciprocal absorbance (log (1/R)), its first and second derivatives (D₁log (1/R), D₂log (1/R)). The PLSR models for prediction samples resulted correlation coefficients (r_p) of 0.74-0.91 and root mean square error of prediction (RMSEP) of 2.018-3.200 °Brix for interactance; r_p of 0.63-0.73 and RMSEP of 3.517-3.863 °Brix for transmission, respectively. The results indicate that interactance displays an obvious advantage over transmission measurement.The reflectance measurement was used to access the discrimination potential in sorting external insect-infested jujubes from intact class. Stepwise discriminant analysis (SDA) was performed to identify the effective wavelengths that best discriminated the insect-infested jujubes from intact jujubes and to derive a discriminant function in classifying the jujubes showing external infestation and those that were free of infestation. The results showed that log (1/R) had better correct classification rate than D₁log (1/R), and D₂log (1/R) for classifying intact, insect-infested and stem-end classes.     

Purification and determination of inhibitory activity of recombinant soyacystatin for surimi application

A recombinant soyacystatin (r-soyacystatin) was tested for its inhibitory activity against cysteine proteinase of Pacific whiting and its activity was compared to that of egg white cystatin. A recombinant soyacystatin expressed in Escherichia coli was purified to electrophoretic homogeneity using phenyl-Sepharose and DEAE-Sepharose. Native egg white cystatin was purified by using affinity chromatography on CM-papain-Sepharose generated in our lab. Egg white cystatin and soyacystatin were tested for proteinase inhibitory activity against commercial papain and also cathepsin L purified from Pacific whiting muscle. The r-soyacystatin exhibited papain-like protease inhibition activity comparable to that of the egg white cystatin, which could inhibit papain and Pacific whiting cathepsin L. The r-soyacystatin subsequently inhibited the autolytic activity of Pacific whiting surimi.     

Protein and water structural changes in fish surimi during gelation as revealed by isotopic H/D exchange and Raman spectroscopy

Structural changes of proteins and water during gelation of fish surimi, have been studied by isotopic H/D exchange of water and Raman spectroscopy assisted by monitoring of rheological characteristics, in order to get insights into the structural and functional properties of surimi gels. The results indicate the following: (i) Protein hydrogen bond rearrangements occur involving mainly α-helix to β-sheet transition, (ii) the relative intensity of the symmetric H₂O stretching band near 3220 cm⁻¹ tends to decrease upon gelation, (iii) H/D exchange reveal a slower deuteration kinetics in the gels as compared to the surimi, (iv) the low temperature scanning electron microscopy shows a smaller pore size of the gel network as compared to the surimi, and suggests that water domains in gel are more inaccessible to D₂O, which is consistent with higher water holding capacity in the gel.     

Effects of konjac glucomannan on physicochemical properties of myofibrillar protein and surimi gels from grass carp (Ctenopharyngodon idella)

The cryoprotective effect of konjac glucomannan (KGM) on myofibrillar protein from grass carp (Ctenopharyngodon idella) during frozen storage at −18 °C and the influence of five levels of KGM (0%, 0.5%, 1%, 1.5%, and 2%) on texture properties, water-holding capacity, and whiteness of grass carp surimi gels were investigated. KGM as a novel cryoprotectant could significantly mitigate the decrease in salt extractable protein (SEP), Ca²⁺-ATPase activity, and total sulphydryl and active sulphydryl contents of myofibrillar protein during frozen storage. KGM at the level of 1% showed the same good cryoprotective effect as a conventional cryoprotectant (10% sucrose–sorbitol, 1:1, w/w). As the levels of KGM increased, breaking force and deformation of grass carp surimi gels increased significantly. Water-holding properties of the surimi gels are improved with the increasing addition of KGM, but the whiteness decreased and the colour became darker. The optimum addition level of KGM was suggested to be 1%.     

大豆中异黄酮含量的测定及其近红外分析

以100份中国核心大豆种质资源为材料,建立高效液相色谱法(HPLC)测定大豆中异黄酮5组分和总异黄酮。扫描大豆的近红外光谱,以傅里叶近红外光谱法(FT-NIRS)与HPLC技术相结合,采用偏最小二乘(PLS)回归和交叉验证法,探讨利用FT-NIRS技术预测异黄酮含量的可行性。总异黄酮近红外预测模型的内部交叉验证其校正决定系数(R2)和交叉检验均方误差(RMSECV)分别为0.8763和0.515,外部验证其校正决定系数(R2)和预测均方误差(RMSEP)则分别是0.9492和0.599。结果表明,利用FT-NIRS预测大豆中总异黄酮含量是可行的,但是各异黄酮组分的近红外模型不能达到准确预测要求。大豆异黄酮近红外模型的建立对今后大豆的异黄酮选育工作可以提供帮助。     

无效变量消除法在油菜籽芥酸近红外无损速测中的应用

探索改善油菜籽芥酸近红外预测模型准确度与精密度的方法,利用无效变量消除法（UVE）,对135个油菜籽样品近红外光谱信号进行筛选,并利用筛选后的光谱对油菜籽芥酸含量进行偏最小二乘法交叉验证。结果表明,UVE法筛选变量后建立的芥酸校正模型对未知样品预测结果的准确度和速度显著优于全波长参与建立的芥酸校正模型。散射校正加一阶导数对光谱预处理,UVE法筛选变量,偏最小二乘法交叉验证建立的校正模型效果最好,其预测值与标准值的相关系数R达到0.92,交叉验证预测均方差为2.2。因此,用UVE进行波长选择后建立的近红外模型,能准确快速地对油菜籽芥酸含量进行定量分析。     

Biochemical and gelling properties of tilapia surimi and protein recovered using an acid-alkaline process

The biochemical and gel properties of tilapia surimi prepared by a conventional washing method and protein isolated using alkaline-acid-aided processes were studied. Solubility and recovery of protein was found to be highest by using a conventional method, followed by an alkaline- and acid-aided process, respectively. Decreases in myoglobin and lipid contents were found in alkaline- or acid-aided process when compared to the conventional process (p < 0.05). The highest breaking force and deformation of kamaboko and modori gels was found in the gels prepared by the conventional washing method. Higher expressible water and whiteness were found in modori gels when compared to kamaboko gels. TCA-soluble peptide contents of conventional surimi gels were lower than those of acid- and alkaline-recovered protein gels. Degradation of myofibrillar protein was observed in acid-isolated protein. Microstructure of kamaboko gels showed more compact network than in modori gels in both conventional surimi and protein recovered using the pH-shift process.     

Nondestructive determination of soluble solids content and pH in tomato juice using NIR transmittance spectroscopy

The potential of near-infrared (NIR) transmittance spectroscopy to nondestructively detect soluble solids content (SSC) and pH in tomato juices was investigated. A total of 200 tomato juice samples were used for NIR spectroscopy analysis at 800–2400 nm using an FT-NIR spectrometer. Multiplicative signal correction (MSC), and the first and second derivative were applied for pre-processing spectral data. The relationship between SSC, pH, and FT-NIR spectra of tomato juice were analyzed via partial least-squares (PLS) regression. PLS regression models were able to predict SSC and pH in tomato juices. The r _c, RMSEC, RMSEP, and RMSECV for SSC were 0.92, 0.0703°Brix, 0.150°Brix, and 0.138°Brix, respectively, whereas those values for pH were 0.90, 0.0333, 0.0316, and 0.0489, respectively. It is concluded that the combination of NIR transmittance spectroscopy and PLS methods can be used to provide a technique of convenient, versatile, and rapid analysis for SSC and pH in tomato juices.     

基于近红外透射光谱的大豆蛋白质和粗脂肪含量快速检测

该研究采用近红外光谱分析技术分别建立大豆蛋白质和粗脂肪含量的近红外检测模型,比较了不同数学处理方法和去散射校正方法及不同回归技术对模型准确性的影响,选出最佳的近红外检测模型,并通过内部验证和外部验证对模型的预测能力进行评价。结果表明:所建立的大豆蛋白质和粗脂肪含量的近红外检测模型的内部验证相关系数分别为0.947 1、0.889 0,外部验证相关系数分别为0.962 2、0.915 5。说明所建立的大豆蛋白质和粗脂肪含量的近红外检测模型具有很好的预测能力,近红外光谱技术可用于大豆成分含量的快速检测。     

Waxy corn starch affecting texture and ultrastructure of sardine surimi gels

 The effect of waxy corn starch (WCS) on the texture, water-holding capacity and microstructure of sardine (Sardina pilchardus) surimi gels in two different systems was studied. In the type A system, increasing amounts of WCS (2, 4, 6 or 8 g/100 g surimi) were added to surimi while maintaining the gel moisture constant at 78%; in the type B system, WCS was added without correcting the gel moisture. Gels were made using two different heat treatments [heat-induced setting (HS) and direct cooking (DC)]. When starch was replaced by surimi (type A) and a heat treatment was applied that favoured formation of a preliminary actomyosin (AM) network (i.e. HS), gel strength (GS) was lower than in the control and decreased as more starch was added, despite an increase in the amount of water held by the gel. Scanning electron microscopy (SEM) showed that the matrix network was fibrillar with a globular surface. Starch appeared to be totally gelatinized and surrounded by a continuous matrix. When the amount of dry matter in gels was increased (type B), in no case did starch have a reinforcing effect, despite an increasing water-holding capacity; SEM showed a denser continuous matrix surrounding the gelatinized starch. Both types of gel made using the heat treatment that allows simultaneous gelling of surimi and gelatinization of starch (i.e. DC) exhibited much poorer GS than did HS gels, while addition of starch made practically no difference to gel texture. The findings suggest that the effect of starch is related to the type of gel matrix that forms upon addition of ingredients. Although such gels contained more water or dry matter, their texture parameters were lower, possibly because of the type of network formed by sardine surimi. Nonetheless, gels of acceptable quality were successfully made with added starch by incorporating less surimi. Received: 18 March 1996     

Waxy corn starch affecting texture and ultrastructure of sardine surimi gels

 The effect of waxy corn starch (WCS) on the texture, water-holding capacity and microstructure of sardine (Sardina pilchardus) surimi gels in two different systems was studied. In the type A system, increasing amounts of WCS (2, 4, 6 or 8 g/100 g surimi) were added to surimi while maintaining the gel moisture constant at 78%; in the type B system, WCS was added without correcting the gel moisture. Gels were made using two different heat treatments [heat-induced setting (HS) and direct cooking (DC)]. When starch was replaced by surimi (type A) and a heat treatment was applied that favoured formation of a preliminary actomyosin (AM) network (i.e. HS), gel strength (GS) was lower than in the control and decreased as more starch was added, despite an increase in the amount of water held by the gel. Scanning electron microscopy (SEM) showed that the matrix network was fibrillar with a globular surface. Starch appeared to be totally gelatinized and surrounded by a continuous matrix. When the amount of dry matter in gels was increased (type B), in no case did starch have a reinforcing effect, despite an increasing water-holding capacity; SEM showed a denser continuous matrix surrounding the gelatinized starch. Both types of gel made using the heat treatment that allows simultaneous gelling of surimi and gelatinization of starch (i.e. DC) exhibited much poorer GS than did HS gels, while addition of starch made practically no difference to gel texture. The findings suggest that the effect of starch is related to the type of gel matrix that forms upon addition of ingredients. Although such gels contained more water or dry matter, their texture parameters were lower, possibly because of the type of network formed by sardine surimi. Nonetheless, gels of acceptable quality were successfully made with added starch by incorporating less surimi. Received: 18 March 1996     

Nondestructive determination of pear internal quality indices by visible and near-infrared spectrometry

The relationships between the nondestructive visible and near-infrared (Vis-NIR) measurements and the internal quality indices of pear fruit were established, and the potential of Vis-NIR spectrometry technique was investigated for its ability to nondestructively measure soluble solids content (SSC) and firmness of intact pear fruit. Intact pear fruit were measured by diffuse reflectance Vis-NIR in 350–1800 nm range. In this study, calibration models relating Vis-NIR spectra to SSC and firmness were developed based on multi-linear regression (MLR), principal component regression (PCR) and partial least squares regression (PLSR) with respect to the logarithms of the reflectance reciprocal log(1/R), its first derivative D₁ log(1/R) and second derivative D₂ log(1/R). The best combination, based on the robust models and the prediction results, was PLSR method with respect to log(1/R) at equatorial position of pear fruit. The PLSR models for prediction samples resulted correlation coefficient (r_p) of 0.912 and 0.854, and root mean standard error of prediction (RMSEP) of 0.662°Brix and 1.232 N for SSC and firmness, respectively. The results indicate that Vis-NIR spectrometry technique could provide an accurate, reliable and nondestructive method for assessing the internal quality indices of intact pear fruit.     

Behaviour of connective tissue in fish surimi on fractionation by sieving

The surimis prepared from the three fish species, red barracuda Sphyraena pinguis, yellow sea bream Dentex tumifrons, and spotted shark Mustelus manazo, were fractionated by sieving through a 30-mesh stainless steel sieve. Chemical analyses revealed significant differences in the collagen content among the residual fraction on the sieve (fraction A), the passed fraction (fraction C), and the original surimi before sieving (fraction B): the fractions A and B showed values 10–20 and 5–10 times higher than those of the fraction C, respectively, for all the species examined. Histological observation indicated the richness of the thick connective tissues derived from myocommata in fractions A and B, while thick connective tissue was hardly observed in fraction C. These results suggested that the present fractionation method may have an effect of reducing the collagen content to about 10–20% of the original value, and that a large part of collagen in fish surimi exists in the relatively thick connective tissue, probably derived from myocommata.