Soymilk Samples Research Articles

The effect of rosemary (Rosmarinus officinalis L.) extract on the oxidative stability of lipids in cow and soy milk enriched with fish oil

Lipid oxidation of fish oil enriched cow milk and soy milk supplemented with rosemary extract stored at 2 °C was studied. Both peroxide value and volatile secondary lipid oxidation products were determined to monitor the progress of lipid oxidation. Rosemary extract inhibited lipid oxidation in fish oil enriched cow milk. In contrast, soy milk samples having much higher unsaturated fatty acid content showed higher lipid oxidation stability compared to cow milk. Reduction in the content of chlorogenic acid during storage suggested that this compound may contribute to the lipid oxidation stability of fish oil enriched soy milk product. Total carnosic acid and carnosol concentration declined much faster in soy milk than in cow milk. It is suggested from the results that food components could have significant impact on the fate of bioactive antioxidant compounds in a specific food product during storage.

Graphene oxide-coated stir bar sorptive extraction of trace aflatoxins from soy milk followed by high performance liquid chromatography-laser-induced fluorescence detection

ABSTRACTMycotoxins are potential food pollutants produced by fungi. Among them, aflatoxins (AFs) are the most toxic. Therefore, AFs were selected as models, and a sensitive, simple and green graphene oxide (GO)-based stir bar sorptive extraction (SBSE) method was developed for extraction and determination of AFs with high performance liquid chromatography-laser-induced fluorescence detector (HPLC-LIF). This method improved the sensitivity of AFs detection and solved the deposition difficulty of the direct use of GO as adsorbent. Several parameters including a spiked amount of NaCl, stirring rate, extraction time and desorption time were investigated. Under optimal conditions, the quantitative method had low limits of detection of 2.4–8.0 pg/mL, which were better than some reported AFs analytical methods. The developed method has been applied to soy milk samples with good recoveries ranging from 80.5 to 102.3%. The prepared GO-based SBSE can be used as a sensitive screening technique for detecting AFs in soy milk.

What is lost in translation: A cross-cultural study to compare the concept of nuttiness and its perception in soymilk among Korean, Chinese, and Western groups

Cross-cultural communication of “nuttiness” can be problematic because the underlying conceptual elements and words used to describe its features may be largely culture-dependent. The present study was conducted to understand similarities and dissimilarities in the concept of nuttiness and its actual perception in our model food system, soymilk, among similar (Korean and Chinese) and dissimilar (Western) food cultures. In total, 110 Koreans, 103 Chinese, and 93 English-speaking, Western consumers were recruited. Subjects were asked to provide a definition of nuttiness and generate examples of nutty and non-nutty foods. They also rated the intensity of the nuttiness of 8 soymilk samples. Sensory profiles of 8 soymilk samples were obtained using 9 trained panelists. Data from the definition task were processed through textual analysis. To identify sensory drivers, consumer ratings of perceived nuttiness intensity in soymilk were projected onto a sensory space constructed from the descriptive profiles of nuttiness. We found significant association between culture and usage of specific words (χ270, 0.05=155.8, p<0.001). For example, whereas the concept of nuttiness in the Korean group involved sensory experiences evoked by sesame, roasted, proteic, or fatty foods, in Westerners, it was more nut-oriented. In contrast, the Chinese group associated nuttiness with general characteristics and hedonic dimensions such as good and comfort, rather than with specific foods. However, sensory drivers of nuttiness in soymilk were consistent across cultures. We found that although the abstract definition of nuttiness clearly demonstrated cross-cultural differences, sensory perception of nuttiness was almost identical across all groups. This suggests that cultural background influences verbalization of one's perception, but not the actual perception itself.

Inactivation of Lipoxygenase in Soymilk by Pulsed Light

Abstract Inactivation of soybean lipoxygenase in soymilk by pulsed light (PL) at different durations and distances from the pulsed light lamp was determined with and without ice surrounding the soymilk sample tray for cooling. The results show that without cooling, the lowest LOX residual activity was 0.37%, 0.00%, and 7.24%, and with cooling the LOX residual activity was 76.3%, 87.2%, and 69.0% for origin fluence of 302 J/cm2, 340 J/cm2, and 567 J/cm2, respectively. The LOX band reduced or disappeared after PL treatments compared with the LOX band control as assessed by electrophoresis. Peroxide value of the soymilk had no significant increase after pulsed light treatment. This research provided evidence that PL treatment could fully inactivate LOX in soymilk, mostly due to heat generated by the PL strobe, therefore the photo-thermal effect was the main factor that impacted LOX activity.

Fast derivatization procedure for the analysis of phytoestrogens in soy milk by gas chromatography tandem mass spectrometry

In this work an optimized GC–MS/MS method, based on a simple and fast derivatization procedure, is proposed for the determination of five phytoestrogens (formononetin, daidzein, coumestrol, genistein and biochanin A) in soy milk. A systematic study of the instrumental analysis conditions was carried out, optimizing different MS acquisition parameters. At the same time, the derivatization procedure was optimized testing three silylating reagents. Among them, N,O-bis-(trimethylsilyl) trifluoroacetamide (BSTFA) was chosen as the most suitable derivatization reagent and an experimental design was performed to find the best conditions for the silylation reaction. The results showed the independence of the derivatization efficiency from the heating treatment applied before analysis, enabling the derivatization directly in the injection port; moreover, the use of a temperature programmed injection enhanced sensitivity and precision of the analysis. The described optimization steps allowed a significant gain in the sensitivity of the overall method, leading to detection limits of 0.1–17.7μgL−1, which are lower or comparable to values reported in the literature for GC–MS analysis of these analytes. High specificity was reached as well, thanks to the careful study of the conditions for tandem MS detection. Precision was good for formononetin, daidzein and coumestrol, with coefficients of variance of 4.7–6.1%; on the contrary, the analysis of genistein and biochanin A was characterized by low precision, probably due to poor stability of the corresponding derivatives. The method was tested on some soy milk samples from the Italian market, proving its suitability for the analysis of phytoestrogens in this complex matrix.

Voltammetric determination of insecticide thiodicarb through its electrochemical reduction using novel solid amalgam electrode fabricated with silver nanoparticles

In this work we investigated the electrochemical behavior of insecticide thiodicarb and carried out its electroanalytical determination using novel solid amalgam electrode fabricated with silver nanoparticles for the first time. Cyclic voltammetry (CV) and square-wave adsorptive stripping voltammetry (SWAdSV) were used to carry out the electrochemical and analytical studies. The best voltammetric response was achieved through the optimization of the experimental and instrumental parameters. Thiodicarb presented its optimum analytical signal in a medium composed of 0.02molL−1 Britton-Robinson buffer at pH 6.0. Two voltammetric peaks were observed, one oxidation peak at Ep=−0.51V and one reduction peak at Ep=−0.64V (vs. Ag/AgCl). The electrochemical process was characterized as an irreversible system. The cathodic signal was used for the quantitative studies performed with SWAdSV. Thiodicarb showed linear dependence over the surface of the amalgam electrode for the concentration range from 1.05×10−7 to 1.52×10−6molL−1 and the limit of detection achieved was 2.03×10−8molL−1. Good repeatability (RSD=3.8%) and reproducibility (RSD=6.1%) were found. The voltammetric method developed here allowed the determination of thiodicarb in soymilk samples at levels below those determined by European Union and Brazil with good accuracy. The results were validated using high-performance liquid chromatography and indicated satisfactory concordance. Based on the data described here, the novel silver solid amalgam electrode presented enhanced analytical performance and showed itself as promising to be used on the routine analysis of thiodicarb in food samples.

Automatic ionic liquid-enhanced membrane microextraction for the determination of melamine in food samples

An innovative miniaturized automatic methodology for the separation of melamine by a hydrophilic microporous membrane and its quantification is proposed. For that an extraction unit containing a hydrophilic microporous membrane was assembled to the system. In the acceptor solution it was used a 10% ionic liquid aqueous solution, instead of an organic hazardous extractant, with an added advantage of the separation process allows the quantification of melamine in liquid samples without any previous treatment. The melamine potentiated the peroxidase catalyzed oxidation of sesamol by hydrogen peroxide with the formation of a fluorescent compound. The effect of physical and chemical parameters in the extraction process and also in the enzymatic reaction used for the quantification of melamine was evaluated. The developed methodology showed detection and quantification limits of 0.07 and 0.22 mg L−1, respectively, and linear range up to 3.00 mg L−1, allowing accurate quantifications of melamine in the concentrations range imposed by food agencies, in a total analysis time of around 5 min (including the extraction process). The novel methodology was applied to milk, powder milk, soy milk and yogurt samples in a precise and accurate fashion. With the sequential injection analysis tool a simple, versatile, rapid, and robust automatic system was implemented avoiding in batch sample pretreatment. Furthermore, the reduction of chemicals consumption and waste generation fulfilled the current recommendations and trends of Green Chemistry.

Study of the inhibitory effect of ferulic acid on short-chain fatty acids in milk samples by dispersive liquid–liquid micro-extraction in combination with fluorescence derivatization

ABSTRACTA sensitive high-performance liquid chromatography (HPLC) method was developed to study the influence of ferulic acid on the formation of volatile fatty acids and lactic acid in milk and soybean milk samples. Volatile fatty acids were extracted by liquid–liquid micro-extraction using chloroform and acetonitrile as the extraction and disperser solvents, respectively. The analytes were derivatized with 2-(5-benzoacridine)ethyl-p-toluenesulfonate that showed excellent fluorescence property and made the sensitive HPLC analysis of short-chain fatty acids become possible. The optimized HPLC sensitivity was in the range of 1.1–1.9 µg L−1. Ferulic acid was added in milk and soybean milk samples to study its preservative effect. The results indicated that ferulic acid with concentration of 0.2% (m/v) could effectively reduce the formation of short-chain fatty acids.

Measurement and analysis of fluorescent whitening agent content in soybean milk based on image techniques

Abstract This paper presents a method for measuring and quantitatively analyzing the fluorescent whitening agent in soybean milk based on image techniques. After collecting the fluorescent images of the soybean milk samples, the top seven wavelet moment invariants are selected according to the sample training and experimental comparison. Then calculate the standard templates of the 49 classes of calibration samples with different fluorescent whitening agent content ranging from 0.02 mg/ml to 0.5 mg/ml. The minimum distance method is carried out to match the testing sample with the calibration template, which realizes the quantitative analysis. To verify the effectiveness of the presented method, the prediction experiment is carried out. Results show that the absolute errors are within 0.005 mg/ml and the relative errors are within 5%, which means this method can measure the fluorescent whitening agent in soybean milk. This research presents a new approach for detecting the illegal fluorescence additive in food production.

Effects of endogenous small molecular compounds on the rheological properties, texture and microstructure of soymilk coagulum: Removal of phytate using ultrafiltration

This study aims to clarify the roles played by endogenous small molecular components in soymilk coagulation process and the properties of gels. Soymilk samples with decreasing levels of small molecules were prepared by ultrafiltration, to reduce the amount of phytate and salts. CaSO4-induced coagulation process was analyzed using rheological methods. Results showed that removal of free small molecules decreased the activation energy of protein coagulation, resulting in accelerated reaction and increased gel strength. However, too fast a reaction led to the drop in storage modulus (G′). Microscopic observation suggested that accelerated coagulation generated a coarse and non-uniform gel network with large pores. This network could not hold much water, leading to serious syneresis. Endogenous small molecules in soymilk were vital in the fine gel structure. Coagulation rate could be controlled by adjusting the amount of small molecules to obtain tofu products with the optimal texture.

Incorporation of thermally activated zeolite into carbon paste electrodes for voltammetric detection of carbendazim traces in milk samples

A simple, inexpensive, yet highly sensitive, and selective novel electrochemical method was developed to quantify traces of carbendazim (MBC) in soy milk and cow milk samples using previously thermally activated zeolite incorporated into carbon paste electrodes. Fourier-transformed infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to examine the structure of untreated and thermally activated zeolite, unmodified carbon paste electrodes, and zeolite-modified carbon paste electrodes (ZMCPEs). The electrodes were electrochemically characterized using cyclic voltammetry, square-wave voltammetry, and electrochemical impedance spectroscopy. The following electrochemical variables were measured: electrode area, number of transferred electrons, electron transfer coefficient, standard rate constant of the electrode reaction, and capacitance of the electrical double layer. The electrocatalytic properties of zeolite were demonstrated by its strong influence on these variables when incorporated into carbon paste in both untreated and thermally activated forms. The electrochemical procedure applied to MBC was developed using ZMCPEs under optimal conditions. MBC oxidation currents exhibited linear concentration in the 12.9–777.7 nmol L−1 range, with a limit of detection of 1.5 nmol L−1. The proposed electrochemical method was employed to quantify MBC in soy milk and cow milk samples. Recovery rates were in the 98.6–99.8 % range, indicating that the method is applicable for quantifying MBC in such samples.

The pH-dependent protection of α-galactosidase activity by proteins against degradative enzymes during soymilk in vitro digestion

α-Galactosidase (α-GAL) dietary supplement is used to alleviate flatulence discomfort caused by raffinose family oligosaccharides (RFOs), but reported efficacy varies among consumers. This study investigated the hypothesis that factors such as stomach acid, gastrointestinal (GI) enzymes (pepsin and pancreatin), and food proteins could affect the activity of α-GAL against RFOs. Strong acidic conditions (pH < 2.0) and GI proteases were found detrimental to α-GAL whereas soy protein could protect α-GAL. In soymilk samples with 1 and 5 mg/mL protein, α-GAL retained 60 and 100% of activity (P < 0.05) throughout the entire digestion (pepsin + pancreatin, 3 h) at pH 2.5 whereas α-GAL was completely inactivated within 1 h of pepsin digestion in water. Isolated soy protein was more protective of α-GAL than soymilk protein. The results were corroborated by SDS–PAGE and the release of galactose as evidenced with the thin layer chromatography.

Preparation of Soymilk Using Different Methods

The present experiment was conducted to prepare soymilk from whole soya seed by using various techniques. Twelve (12) soymilk samples were prepared by three different methods with four concentration level. Each sample was analyzed for proximate composition and sensory qualities were evaluated by a taste panel. No significant difference was found between dehulled soy seed blending milk and whole soy seed powder milk. But 125g concentration obtained highest score from the judges. From the results of chemical analysis, significant difference was found in terms of moisture, total solids, solids- not- fat, protein, fat, carbohydrate, ash content and acidity percentage. Dehulled soy seed blending milk contained more moisture, protein, fat and ash content. On the other hand, a sharp increase of nutrient concentration was observed with the increase of soymilk concentration. But soymilk of 150 and 175g concentration become thicker after boiling which had fewer acceptances by the judges. Considering the physical and chemical properties of all samples, it is recommended that 125g concentrate dehulled soy seed blending milk may be prepared in industrial scale.

Analysis of water-soluble bioactive compounds in commonly consumed soymilk in China

Soybean, an important source of many bioactive compounds, is of interest because of the health benefits it confers. We compared the contents of different bioactive components, such as peptides, amino acids, isoflavones, saponins, and oligosaccharides, in five commonly used soymilk types in China, using an amino acid analyzer, high-performance liquid chromatography, and an ultraviolet spectrophotometer. The concentrations of almost all bioactive compounds, except for stachyose and raffinose, were significantly higher in homemade soymilk (HSM) samples than in ready-made soymilk (RSM) samples. HSM created using non-genetically modified soybeans contained the most amino acids (21.7%), water-soluble proteins (25.6%), peptides (11.90%), and water-soluble isoflavones (1175μg/mL). HSM made using genetically modified soybeans contained the most saponin (36.7mg/mL). RSM samples contained the most stachyose and raffinose. These findings provide basic information for evaluating the function of soymilk with regard to its bioactive ingredients.

Development of ELISA and Colloidal Gold-PAb Conjugate-Based Immunochromatographic Assay for Detection of Abrin-a.

When abrin-a was combined with several polyclonal antibodies (PAb), the detection limit could be increased. In this way, a monoclonal antibody (capture) and polyclonal antibody (detection) sandwich enzyme-linked immunosorbent assay (ELISA) and a colloidal gold-PAb conjugate-based immunochromatographic assay for detection of abrin-a were developed. The ELISA had a detection limit of 3.9 ng/mL for abrin-a in standard solution and 7.8 ng/mL in soybean milk, and was more sensitive than polyclonal antibody (capture) and monoclonal antibody (detection) ELISA, which had a detection limit of 15.6 ng/mL. The test strip had a detection range of 50 to 500 ng/mL for abrin-a and a detection limit in standard solution or soybean milk samples of 50 ng/mL. However, the test strip had a reduced detection capability compared with a colloidal gold-monoclonal antibody conjugate-based immunochromatographic assay test strip, which had a lower detection limit of 10 ng/mL. The developed ELISAs and test strip show the specificity towards abrin-a and have no cross-reactivity towards abrin-b, -c, -d, ricin, or the agglutinins from either castor beans or rosary peas.

Identification of potential bioactive peptides generated by simulated gastrointestinal digestion of soybean seeds and soy milk proteins

In this work, the bioactive peptides produced during in vitro gastrointestinal digestion of soybean seeds and soy milk were investigated. The analysis was performed on extracted protein samples from soybean seeds and milk or directly on untreated soy milk. Proteins samples were subjected to simulated gastrointestinal digestion and then analyzed by nano-liquid chromatography coupled to tandem mass spectrometry for peptide sequencing. The identified peptides were 1173 in soybean seed samples, 1364 in untreated soy milk samples and 1422 in soy milk samples in which proteins were extracted by precipitation. The peptide identifications were then employed to search specific databases and look for the presence of bioactive peptides in the investigated samples, either with known biological activity or with potential antimicrobial activity. Results pointed out that soybean proteins underwent an extensive degradation process during gastrointestinal digestion and generated a large number of bioactive peptides, some with established activity, some with predicted antimicrobial activity. Finally, the supernatants collected after protein precipitation with acetone from both soybean seeds and soy milk were also analyzed to evaluate the presence of peptides produced by the action of endogenous proteases. Likely, peptides found in soy milk samples could be formed during food processing.

A Novel Method of Measuring Fat Content in Soybean Milk Based on Y-Type Optical Fiber Sensor

Abstract A new method of measuring fat content in soybean milk at room temperature (25°C) based on the Y-type optical fiber sensor is presented. The measurement system consists of a light source, Y-type optical fiber sensor, detector, thermoelectric cooler (TEC), preamplifier, second-level amplifier, A/D converter, and microprocessor. Based on the Mie theory, the diffuse reflection light intensity is adopted as the optical parameter representing the fat content in soybean milk. In this way the standard model of the system was established based on the diffuse reflection light intensity (the output voltage) of 40 soybean milk samples with different fat content. A prediction was also made to verify the measurement accuracy of the system (the prediction errors are within ±3 % of results). Results of this study indicate the feasibility of using this technology for soybean milk fat analysis that is suitable for the milk laboratory or field analysis.

Studies on shelf-life of fresh soymilk

SUMMARY : Fresh soymilk was inspected for quality attributes like viscosity, TSS, titrable acidity, pH, standard plate count, yeast and mould count daily for sample stored in refrigerated condition and at the regular interval of 4 hrs for sample stored in ambient condition. On the basis of the quality attributes, it was observed that fresh soymilk samples were acceptable upto 5 days in refrigerated condition while same samples were acceptable upto 16 hrs in ambient temperature condition from the day of preparation. Thus, the study reveals that, fresh soymilk sample stored at refrigerated condition has better shelf-life.

An Aromatic Lexicon Development for Soymilks

The aim of this work was to develop an aromatic lexicon for evaluating different soymilks with two descriptive methods and an instrumental assistance. A list of 20 terms was generated by eight trained panelists through gas chromatography olfactometry and mass spectrum with free choice profiling for three different soymilk samples. During this phase, panelists randomly used words they were familiar with to evaluate the aroma they experienced and then make an agreement on these terms. Data were analyzed via generalized procrustes analysis, two-way ANOVA, and high-frequency analysis to select the most suitable terms. Based on the above list, 14 panelists evaluated the three soymilk samples with citation frequency profiling. The panelists chose the terms from the list that they considered as the most appropriate way to describe the samples. The data were analyzed by corresponding analysis to verify the performance of the panel and chi-square (χ2) analysis to determine the discriminate descriptors, including mushroom, cardboard, beany, porridge, and bean fragrance. Accordingly, the five terms consisted of the aromatic lexicons in soymilks in the present work, which were different from previous studies.

EFFECT OF TREATMENTS, CMC AND STORAGE CONDITIONS ON SENSORIAL QUALITY OF MANGO FLAVOURED SOYMILK

In the present research work effect of different treatments on physico-chemical and sensory properties of soymilk was studied. Also, effect of Sodium carboxymethyl cellulose (CMC), sucrose and mango flavor on quality of soymilk was determined. Soymilk samples were prepared by three different methods. The control sample (sample A) was prepared as per the standard procedure reported in literature. The other two samples were prepared by slight modification in the process use for control sample preparation. Microwave treatment at 2450 MHz for 5 min prior to grinding was given in sample B. Sample C was prepared by giving autoclave treatment to the soaked soybeans and grinding was performed with the use of hot water. Among all the treatments autoclave treatment gave best quality soymilk (Sample C) with respect to flavor, taste and overall acceptability. The quality of soymilk (Sample C) was further improved by using 0.2% CMC with respect to viscosity and mouth feel. Also, mango flavored soymilk containing 0.2% CMC, 15% sucrose and 0.1% mango essence scored maximum sensory score among all formulations with respect to color, flavor, taste, mouth feel and overall acceptability and was stable for consumption for about 25 days at room temperature storage and 60 days at refrigeration temperature storage.