2014, 32(5):1-5. DOI: 10.3969/j.issn.2095-6002.2014.05.001
Abstract:The current situation, main existing problems and trends of post-harvest processing of leafy vegetables were clarified in this study, and the key technologies to be solved during leafy vegetables processing were also discussed. The solution methods of fresh-cut process, freeze-drying process, disinfection process, packaging technology and equipment automation were emphatically analyzed. All these would give a clear instruction for the processing of leafy vegetables.
2014, 32(5):6-9. DOI: 10.3969/j.issn.2095-6002.2014.05.002
Abstract:Quality and safety problems will exist in grain and oil products processing which may manifest in three aspects:raw materials, processing technology, illegal indiscriminate use of additives.The safety problems in the processing of raw materials present as pesticide residues in grains, mycotoxin contamination, heavy metals pollution etc, and safety problems in machining process present as excessive processing, trans fatty acid and harmful substances migration to packaging materials. Quality and safety countermeasures of grain and oil products suggest strengthening supervision of quality and safety, increasing the propaganda dynamics, strengthening the process control and management, constructing quality and safety traceability system.
2014, 32(5):10-14. DOI: 10.3969/j.issn.2095-6002.2014.05.003
Abstract:Food safety is the national security”. As a food import and export big country, the security problem of China is becoming more and more important. Comparing with the developed countries, Chinese food import and export safety management is far behind in many aspects such as standard in laws and regulations, food safety regulatory system, pesticide residue limits, detection technology etc. Therefore, it is necessary to make a further study on the safety problems of food import and export and propose the corresponding countermeasures.
2014, 32(5):15-20,40. DOI: 10.3969/j.issn.2095-6002.2014.05.004
Abstract:The cryoprotective effect of degraded konjac glucomannan (KGM) on the grass carp myofibrillar was studied and five degradation methods including acid hydrolysis, enzymatic hydrolysis (dextranase, cellulase), γ-irradiation hydrolysis, and microwave assisted hydrolysis with hydrogen peroxide were used. The cryoprotective effects of KGM with different degradation products were compared and freezing points were also measured. The results showed that the degradation products of KGM had a cryoprotective effect on the grass carp myofibrillar during the frozen storage. When the amount of degraded KGM (enzymatic hydrolysis, γ-irradiation hydrolysis) was 0.5%, the cryoprotective effect was better than that of commercial cryoprotector. The degraded KGM could decrease the freezing point and enthalpy of water as a new cryoprotector.
2014, 32(5):21-26. DOI: 10.3969/j.issn.2095-6002.2014.05.005
Abstract:The synergy effect of konjac glucomannan(KGM) and κ-Carrageenan (KC) is one of an important research fields of polysaccharide interactions.The study of their interaction site can help to reveal many essential problem of the system, and it also plays a key role in the building and application of stable network system.The changes of KGM and KC blends rheological property in three ratios with microwave and heating process were studied , and their action sites were also measured through rheometer and molecular dynamics simulation, respectively. The results showed that the interaction between KGM and KC was changed after microwave treatment. The higher was the KC concentration, the better of their interaction. The hydrogen bonds between OSO3 of KC and KGM molecular were the main forces to maintain the complex system stable, which indicated that the OSO3 residue was the main KC and KGM interaction site. These results suggested that KC played a dominant role in KGM and KC composite system.
2014, 32(5):27-34. DOI: 10.3969/j.issn.2095-6002.2014.05.006
Abstract:methylthiopropanol in Sesame-Flavor Liquor was analyzed by gas chromatography-flame photometric detector (GC-FPD) in this study. The wine was concentrated 50 times and extracted by dichloromethane for sample pretreatment. The chromatographic condition carried out that:polar chromatogra-phic column DB-FFAP (60m×0.25mm×0.25μm), programmed temperature, inlet temperature 260℃, detector temperature 200℃. External standardmethod was adopted. The results showed that with the concentration of 5-100mg/L of 3-methylthiopropanol the linear correlation coefficient( R2 ) was 0.9913, LOD was 2.5mg/L, LOQ was 5mg/L, while with the level of 8,30,80mg/L recovery rates were between 84.3% to 89.7%, R.S.D. ranged from 3.7% to 4.6%. Five major Sesame Flavor Liquor corporations and 18 samples were inspected. The 3-methylthiopropanol couldn't be detected in commercial wines including the corporation of Ⅰ and Ⅲ, original wines such as Ⅰ, Ⅱ, Ⅲ and Ⅴ. While the concentration of 3-methylthiopropanol in the commercial wines of Ⅱ-a, Ⅱ-b, Ⅱ-c, Ⅱ-d and Ⅴ-a were 1.03,0.35,0.80,0.67,0.18mg/L, respectively. In the corporation of Ⅳ original wine and commercial wine, its concentration were all below 0.1mg/L.
2014, 32(5):35-40. DOI: 10.3969/j.issn.2095-6002.2014.05.007
Abstract:To screen high GABA-producing Monascus strains from the laboratory, effects of Monascus inoculum, temperature, time, and the sodium glutamate content on GABA production were studied. Taking the production of GABA as the index, single factors and the orthogonal experiment were implemented to attain the optimum fermentation conditions, the temperature of Monascus CH-1 30℃, optimum fermentation time nine days, optimum inoculation 17%, and optimum dosage of sodium glutamate 0.10g. The GABA yield by Monascus CH-1 was 1.93mg/g and the citrinin content was 0.01μg/g below the national standards. The more forms of red kojic rice food product can be developed.
2014, 32(5):41-45. DOI: 10.3969/j.issn.2095-6002.2014.05.008
Abstract:The aim of the present study was to evaluate the in vitro cholesterol removal ability of different lactic acid bacterial strains. Single factor experiments were carried out to explore the influences of oxgall addition, cholesterol addition, medium pH, and incubation time on the cholesterol removal ability of the strains. The results showed that cholesterol removal rate was significantly affected by the above factors. Under the same conditions, considerable variation was found among lactic acid bacterial strains with regard to the ability to assimilate cholesterol from a laboratory growth medium. Generally, the highest cholesterol removal rate (more than 50%) was obtained under the condition of the oxgal concentration 4-6mg/mL, cholesterol concentration 190-230mg/L, medium initial pH 5-7, and incubation time 11-23h.
2014, 32(5):46-49. DOI: 10.3969/j.issn.2095-6002.2014.05.009
Abstract:The nutrient components of eight cultivars onion powder produced in Shandong province were analyzed to select the specific varieties for onion processing. The results showed that:The nutrient components including total sugar, protein, and crude fiber had significant differences except ash. The content of total sugar was the highest with the range of 47.29%-69.51%, followed by protein, crude fat, crude fiber and ash. The content of flavonoid was between 76.13mg/100g to 556.63mg/100g, and hydrolyzed amino acid content was between 8.54% to 15.31%. Potassium content in minerals was the highest, followed by P, Ca, Mg, Na, and Fe content was closed to zero. White onion No.2 and red A5 could be exploited as specific processing cultivar, and the onion oil and polysaccaride could be extracted from the former, and A5 could be used as the feed.
2014, 32(5):50-55. DOI: 10.3969/j.issn.2095-6002.2014.05.010
Abstract:Lycopene is a food coloring agent and the outstanding antioxidant and anticancer properties of lycopene make it an ideal component for daily food supplements. In this paper, the research advances of lycopene extraction by different techniques in recent ten years were reviewed, including conventional solvent extraction, supercritical CO2 extraction, enzyme-assisted extraction, ultrasound-assisted extraction, microwave-assisted extraction, ultrasonic-microwave assisted extraction, ultrahigh pressure assisted extraction, and high-intensity pulsed electric fields assisted extraction. The advantages and disadvantages of the techniques were given, which could supply useful information for further research on lycopene and other natural pigments.
2014, 32(5):56-62,79. DOI: 10.3969/j.issn.2095-6002.2014.05.011
Abstract:In the production process of fried White Feather Chicken nuggets, biological, physical, and chemical hazard analysis methods based on the HACCP system were applied. The potential hazards existing in pre-processing, frozen treated, and storage process were analyzed and the critical control points and critical limits were revealed. The HACCP plan was made based on the raw materials reception, additives launching, and metal detection to ensure the product quality and safety of fried White Feather Chicken nuggets.
2014, 32(5):63-68. DOI: 10.3969/j.issn.2095-6002.2014.05.012
Abstract:Gas chromatography (with a FPD detector) was applied to the quick determination of 13 organophosphorus pesticides residues in green tea with sample pretreatment by ultrasonic assisted extraction and dispersive solid phase extraction. The sample (5 g) was extracted with 20 mL acetonitrile(containing 1% acetic acid) by ultrasonic, and the extract was purified by dispersive solid-phase extraction with graphitized carbon/primary secondary amine (GCB/PSA). After the high speed centrifugation, nitrogen flushing concentration, and filtration, the sample was detected by GC-FPD. At the fortification level from 0.02-0.10mg/kg, the average recovery of 13 organophosphorus pesticides was 84.78%-116.72%. Meanwhile, the relative standard deviation (n=3) was from 0.12%-9.32% and the limits of detection was 0.0008-0.01mg/kg. The method was simple, rapid, accurate, and low-cost with few impurity disturbs and suitable for organophosphorus pesticides detection in green tea. This method was applied for the detection green teas in local markets, and the results of all organophosphorus pesticides were under the maximum residue limits of GB 2763—2012.
2014, 32(5):69-73. DOI: 10.3969/j.issn.2095-6002.2014.05.013
Abstract:The equipment structure and characteristics of ultrasonic extraction circulation were intro-duced based on the advantages and disadvantages of domestic ultrasonic extraction equipment. A set of continuous cyclic ultrasonic extraction production line was designed combined with cycle ultrasonic extraction technology. Material packaging system, material conveying system, ultrasonic extraction system, extracting enrichment system, and recovery system were included in this production line. According to the dynamic relationship of ultrasonic extraction of active ingredients from plant resources, the reasonable process parameters were set, and actual production data were obtained. Meanwhile, the advantage of the production line was compared with other ultrasonic extraction device.
2014, 32(5):74-79. DOI: 10.3969/j.issn.2095-6002.2014.05.014
Abstract:The accuracy of the prediction model is affected by the near-infrared spectrum of flour and flour ash contents was quantitative analyzed. While the presence of outlier data seriously interfere with the reliability of the model, therefore, it is essential to identify and deal with the outlier samples to improve the predictive ability. Mahalanobis distance and the Monte Carlo cross validation (MCCV) methods were used to remove the outlier samples. When the weight coefficient was 1.5, excluding sample number was 3 with the former method it could get the best results, and the related coefficient (R2) was 92.67, cross-validation mean square error (RMSECV) was 0.0485. While with the latter method the correlation coefficient (R2) was 94.64, cross-validation mean square error (RMSECV) was 0.0411.Therefore, Mahalanobis distance method can improve the calibration model and prediction accuracy to a certain extent, while the calibration model and prediction accuracy of MCCV without outliers samples was better than that of the Mahalanobis distance method.
2014, 32(5):80-82. DOI: 10.3969/j.issn.2095-6002.2014.05.015
Abstract:The evaporation residue levels of imported silicone and latex pacifiers were determined and analyzed in two food simulants-distilled water and 4% acetic acid solution. The results showed that the evaporation residue levels in food simulants were related with the pacifier materials and its level in latex pacifiers was higher than that in silicone pacifiers with both of two food simulants.