Table of Content

15 October 2015, Volume 17 Issue 5

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Opportunities and Challenges of Food Physical Processing Science and Technology Innovation in China

JIA Jing-dun

2015, 17(5):  1-5.  DOI: 10.13304/j.nykjdb.2015.577

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Food physical processing is a new field of food processing, which merges  modern physics and engineering technology and traditional food industry. In order to promote the food physical processing science and technology innovation in China, this paper discussed opportunities and challenges from aspects of the status, problems and development proposals, and analyzed the effects of food physical processing on food industry at the current stage by explanation of its connotation and extension. For promoting food physical processing science and technology innovation in our country this paper also proposed suggestions from discipline construction of food physical processing, and optimaizing the innovation chain for food physical processing.

Research Status and Prospects on Meat Freezing and Thawing, and Non-destructive Determination Technology

HU Hong-hai, LU Li-li, ZHANG Hong*

2015, 17(5):  6-10.  DOI: 10.13304/j.nykjdb.2015.575

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Freezing is one of the important methods of meat storage, which can effectively extend the shelf life of meat. Freezing-thawing process will produce a great impact the quality of the meat, such as lipid oxidation, protein denaturation, changes in microstructural, water holding capacity, color and texture. In order to improve the market competitiveness of meat, it is necessary to optimize freezing-thawing process parameters and storage conditions to improve product quality. This paper reviewed the research status on meat freezing and thawing method, effects of freezing-thawing on meat quality and rapid and non-destructive testing technology to provide reference for livestock and poultry meat storage.

Research Progress on Non-destructive Technology for Quality Detection of Eggshell

SUN Li, CAI Jian-rong*, LI Ya-qi, YUAN Lei-ming, XU Deng-cheng

2015, 17(5):  11-17.  DOI: 10.13304/j.nykjdb.2015.508

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Eggshell quality is one of the import parameters for fresh egg, hatching egg and egg product. To realize the intelligent quality detection is an essential step in the process of poultry production, management and processing. It can not only ensure the egg quality and improve the utilization rate, but also is an pre-condition for realizing automation of egg product primary processing. It is of actual value and realistic significance. This paper reviewed the research progress made in infrared spectroscopy, machine vision and vibrations technology in nondistructive detection of eggshell quality; analyzed the problems and difficulties exsisting in above mentioned technology; and prospected the application of on-line detection for eggshell quality.

Research Progress on Detection Methods for Fish Freshness

LV Ri-qin, HUANG Xing-yi*, XIN Jun-wei, JIANG Fei-yan, MU Li-jun, GU Fei-fei, YA

2015, 17(5):  18-26.  DOI: 10.13304/j.nykjdb.2015.520

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Fish is one of the most important sources of animal protein consumed by human. Fish freshness directly affect the health even life safety of consumers. The traditional detection methods for measuring fish freshness mainly include sensory evaluation, microbial detection and physical and chemical detection. The new detection methods include sensory bionic technology, spectroscopy, biosensors & bio-impedance technology. This paper all sidedly introduced the main technology and methods for rapid evaluation of fish freshness, and also carried out appropriate comparison and discussion. The paper prospected the future research progress trend, and provided a reliable theoretical basis for further studying and developing fish freshness decision specification.

Studies on Non-destructive Testing Method of Moldy and Budding Peanuts by Near Infrared Spectroscopy

HUANG Xing-yi, DING Ran, SHI Jia-chen

2015, 17(5):  27-32.  DOI: 10.13304/j.nykjdb.2015.519

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A nondestructive testing method was studied for moldy and budding peanuts by Fourier transform near infrared spectroscopy combined with K Nearest Neighbor pattern recognition method. According to the sensory characteristics of peanut and previous research experience, the samples were divided into 4 classes: normal, mild mildew, putrefactive spoilage and budding. Integrating sphere diffuse method was used for the collection of peanut spectra, the wave band was from 4 000~10 000 cm-1. Second order derivative method was applied for spectroscopy data pretreatment and Synergy Interval Partial Least Squares (Si-PLS) method was used for the spectral variables selection.  The principal components analysis (PCA) was used for the data space dimensionality reduction. Then KNN recognition model was established. The identification rates of KNN model training set and forecast set were both 98.84%. The result indicated that near infrared spectroscopy technology plus KNN method was feasible for nondestructive testing of moldy and budding peanuts with good effect.

Non-touching Detection on Benzoyl Peroxide Added in Wheat Flour Using Raman Scattering Spectroscopy

ZHAO Juan, PENG Yan-kun*

2015, 17(5):  33-39.  DOI: 10.13304/j.nykjdb.2015.498

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In order to carry out the non-destructive, rapid identification of illegal or excessive additives in flour, this study took benzoyl peroxide as detecting object, adopting  Raman scattering spectroscopy technology to acquire sterling Raman spectrum from flour and benzoyl peroxide, screened out Raman characteristic lines, which could identify benzoyl peroxide. In order to further verify the feasibility of mixing benzoyl peroxide with flour when detecting by Raman spectrum, 10 samples with different ratioes of mixture were prepared to collect the Raman spectrum data. The Savitzky-Golay (S-G) algorithm and 8th order polynomial fitting algorithm were applied to smooth the noises and correct the background signal in Raman spectrum to retain Raman spectrum signal in initial data. After analyzing the pure benzoyl peroxide Raman spectrum, many obvious Raman peaks were found at 619 cm-1, 848 cm-1, 890 cm-1, 1 001 cm-1, 1 234 cm-1, 1 603 cm-1, 1 777 cm-1. Among them the intensity of Raman peak at 1 001 cm-1 was the highest. Therefore, the of Raman peak was selected at 1 001 cm-1 as characteristic peak for identifying benzoyl peroxide. Raman peak could clearly be detected  at the location of 1 001 cm-1 from the Raman scattered spectrum of the 10 mixed samples after smooth and baseline correction. These results indicated that Raman spectrum technology could identify benzoyl peroxide adulteration in wheat flour effectively, rapidly and without touching.

Research Progress on Pasteurization and Sterilization using High Pressure Carbon Dioxide Technology

HOU Zhi-qiang, ZHAO Feng, RAO Lei, WANG Yong-tao, LIAO Xiao-jun*

2015, 17(5):  40-48.  DOI: 10.13304/j.nykjdb.2015.534

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High pressure carbon dioxide (HPCD) has properties of subcritical and supercritical carbon dioxide. It has good solubility and diffusivity and can generate high pressure, acidification, explosion, anaerobic, and other effects during food processing process, and has good inactivation effect. Recently, as a new non-thermal technology, it has won more and more attention from the researchers. This paper reviewed the research status of HPCD on microorganisms of vegetative cells and spores; and analyzed the present domestic and abroad research progress in inactivation mechanism of HPCD, so as to provide theoretical references for future research and application of HPCD.

Comparative Analysis of Ohmic Heating Sterilization and Pulsed Electric Field Sterilization

WANG Man-sheng, ZENG Xin-an*

2015, 17(5):  49-54.  DOI: 10.13304/j.nykjdb.2015.514

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Recently, physical sterilization technology has been widely applied in the field of food processing, including the traditional thermal sterilization technology, such as ohmic heating sterilization, and the new type non-thermal sterilization technology, such as pulse electric field sterilization. Ohmic heating technology and pulsed electric field sterilization are linked with each other, but different in the field of sterilization. In order to understand and apply those 2 physical sterilization technologies more clearly, this paper comparatively analyzed their historical resources, principle of bactericidal effect, and application scope, etc..

Disinfection Technology of Cold Plasma and its Application in Food

WANG Jia-mei1, HUANG Ming-ming2, QIAO Wei-wei2, ZHANG Jian-hao2*

2015, 17(5):  55-62.  DOI: 10.13304/j.nykjdb.2015.513

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Cold plasma is a mixture with high ionized state at atmospheric pressure. Within the mixture, there are lots of active species and particles which can attack the cells of microorganism to control their normal growth and lead to death. But there is no significant temperature changes during this reaction process. As a non-thermal sterilization method, cold plasma has a broad prospect of application in food disinfection industry. This paper briefly introduced the generation of cold plasma, their emerging system and major reactive species. The paper also introduced the research activities about cold plasma application in food industry.

A New Spices Heat Sterilization Technology and Equipment based on Skin Effect

CAI Jian-rong1, YANG Jun-yi1, ZHUANG Xiao-bo2, JIANG Xiang1, TAO Yi1, SUN Li1

2015, 17(5):  63-67.  DOI: 10.13304/j.nykjdb.2015.482

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To achieve the fluidized transport of solid materials, a set of sealed sterilization cavity was designed. The spiral conveyor with scraper was installed in the intra-cavity, and the conveyor was heated by the high-frequency low-voltage power. The spice in the intra-cavity was pushed forward by the conveyor to realize the continuous feeding and sterilization. A small amount of hot dry-steam was pumped into the sterilization cavity to auxiliarly heat and take excess moisture away from the heated spice. After the stage of sterilization process, the qualified spice was transformed into the fast cooling cell to lower down the temperature, and until to the rooms temperature, then was packaged directly. The overall sterilization processes were conducted in a closed space, which realized the parameters measurement in every critical control point (CCP). By the preliminary experiment, when the amount of chili powder sterilization was 1 000 kg/h, the total number of colonies could be controlled under 10 000 CFU/g.

Studies on Radio Frequency Heating to Inactivate Microorganisms in Broccoli Powder

ZHAO Wei, YANG Rui-jin*

2015, 17(5):  68-74.  DOI: 10.13304/j.nykjdb.2015.455

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Recently, the safety of food with low water activity (aw), including dried vegetables powder, has been a major concern of the people. Although the microorganism could not grow in low aw foods, it can survive for a rather long period of time. Once the environment becomes suitable, a severe food safety problem would occur. Therefore, it is necessary to develop decontamination methods to improve the safety of low aw foods. Taking broccoli powder as material, this paper disinfected 27.12 MHz pilot scale RF system by 6 kW radio frequency (RF), and studied the heating pattern and temperature distribution during RF heating. It was found that the temperatures in the interior and central parts of the sample were much higher than that in the surface. Overturn and rotation during RF treatment was proven effective to improve the heating uniformity. This paper also studied the situation of microbial reduction and color change of the sample during different periods of RF heating. The results showed that RF heating for 5 min had a high efficiency in microbial inactivation with insignificant color degradation. The cold shock treatment (freezing at -18℃ for 48 h) following RF heating could further reduce microorganism in broccoli powder from 3.0 log CFU/g to less than 1.0 log CFU/g. Cold shock combined with RF heating is a promising disinfection technology for food of low aw. It can preserve to the large extent the original superiority of low moisture foods.

Research Progress on Liposome Preparation Using Dynamic High Pressure Micro-fluidization

CHEN Xing, ZOU Li-qiang, LIU Wei*, PENG Sheng-feng

2015, 17(5):  75-80.  DOI: 10.13304/j.nykjdb.2015.480

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The liposomes prepared by traditional method has problems such as  large particle size, low encapsulation efficiency, distribution uneven, and many organic reagent residues etc. Dynamic high pressure microfluidization (DHPM) is a new kind of liposome preparation technology, which combines the advantages of water jet technology, impinging stream technology and the tranditional high pressure homogenization technology. DHPM can remedy the defect of traditional liposome preparation method, and provide basic technical support for realizing industrial production of liposomes with small particle size, high encapsulation efficiency, and edible safety. This paper brievely introdued the liposome preparative technique, the application of DHPM in liposome preparation, and the advantages and disadvantages of DHPM, aiming to provide technical reference for liposome industrilized production.

Studies on Dual-frequency Countercurrent Energy-gathered Ultrasonic-assisted Extraction Technology and Antioxidant Activity of Inulin

WANG Ke, MA Hai-le*, YE Xiao-fei

2015, 17(5):  81-87.  DOI: 10.13304/j.nykjdb.2015.460

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Helianthus tuberosus L. is a natural herb with excellent health care function. Ultrasound is widely used for auxiliary extraction of natural ingredients. Using dual-frequency countercurrent energy-gathered ultrasonic-assisted extraction technology, this paper studied the effect of ultrasound on extraction ratio and antioxidant activity of inulin polysaccharide, influence of each factor sorting order was power density > solid/liquid ratio > time > temperature > pulse/interval ratio. The optimum technology parameter was ultrasound dual-frequency combination of 20 kHz/35 kHz, ultrasound pulse/interval ratio of 4 s/3 s, ultrasound power density of 250 W/L, solid-liquid ratio of 1∶20, extraction temperature of 55℃ and extraction time of 15 min. Under this condition, the inulin extraction ratio was 56.35%, while under the same condition by hot water extraction method the extraction ratio was 33.89%. Inulin showed rather good antioxidant activity. Ultrasound had no obvious influence on antioxidant activity. Antioxidant activities of samples treated by diverse methods were significantly different, in which water crude extraction had the greatest·DPPH depleting capacity, and ultrasonic ethanol sediment showed the best reduction force and Fe2+ chelating ability, and the purified ultrasonic ethanol sediment had the highest hydroxyl radical scavenging rate.

Studies on Optimization of Extraction Technology Assisted by Pulsed Electric Field of Total Flavonolds from Rape Pollen Using Response Surface Methodology

XIONG Xia-yu, ZENG Xin-an*| WANG Man-sheng, ZHANG Zhi-hong

2015, 17(5):  88-93.  DOI: 10.13304/j.nykjdb.2015.515

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Taking rape pollen as raw material, by using pulsed electric field wall-breaking method, this paper studied the extraction effect of total flavones from rape pollen. On the basis of testing 3 single factors——electric field intensity, pulses number and backflow temperature, taking total flavones extraction rate as response value, the best extraction technology for total flavones were optimized by Box-Behnken method. The results showed that electric field intensity had a significant effect on rape pollen cell wall breaking. Under the optimal extraction technology condition, i.e. electric field intensity of 28 kV/cm, pulses number of 508 and backflow temperature of 82℃, the total flavones extraction rate could reach 4.508%.

Effect of Low-frequency Magnetic Feld on Gamma-aminobutyric Acid Produced by Monascus purpureus in Solid-state Fermentation

WAN Yun-lei1, HAN Hong-xia1, LI Li1, WU Xiao-jie1, GAO Meng-xiang1,2*

2015, 17(5):  94-98.  DOI: 10.13304/j.nykjdb.2015.478

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Monascus purpurcus was treated with low-frequency magnetic field (LF-MF) to produce gamma- aminobutyric acid (GABA) through fermentation. This paper studied the effect of LF-MF intensity, treating time and treating stage on GABA production by solid-state fermentation of Monascus purpurcus. The paper also studied fermentation kinetics of GABA produced by Monascus purpurcus under optimal treatment condition. The result showed that the growth rate and final output of GABA increased 31.6% and 35.7%, respectively, when Monascus purpurcus was treated by LF-MF at 1.6 mT and at the 4~8 d during its fermentation. The LF-MF can intensify or inhibit the GABA output. This might be related to LF-MFs ability to change metabolic pathway of GABA.

Effect of Statistical Magnify Field-assisted Liquid Fermentation on Yield of Mycelia and Triterpenoid of Antrodia cinnamomea

WANG Bei, WANG Wei-wei, MA Hai-le*, YE Xiao-fei

2015, 17(5):  99-105.  DOI: 10.13304/j.nykjdb.2015.481

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This paper discussed the basic rules of magnetic field in promoting the liquid state fermentation of Antrodia cinnamomea by studying different magnetic field intensities and acting times on yields of mycelia and triterpenoid. GC-MS, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to compare and analyze the differences existing in the biological active components, volatile components in fermentation liquor, microscopic morphology and triterpenoid components of the mycelium gained through normal liquid state fermentation and magnetic field-assisted liquid state fermentation. The results showed that after 60 mT intensity treated for 36 h, the promotion effect of magnetic field on mycelia growth and triterpenoid yield was the strongest. The yield of A. cinnamomea increased by 23.53% and the yield of triterpenoid increased by 28.19%. The result of GC-MS indicated that the volatile components by these 2 fermentation liquors were basically the same, but the contents were remarkably different. SEM result showed that the mycelia morphology of A. cinnamomea treated by magnetic field was looser than that treated by normal fermentation method. According to FTIR, there were no significant differences in triterpenoids components observed with these 2 treatments. It can be concluded that magnetic field assisted fermentation is able to improve mycelia and triterpenoid yields without reducing their quality.

Application of Dynamic High-pressure Micro-fluidization in Modification of Food Macro-molecule

CHEN Jun, DAI Tao-tao, LIU Cheng-mei, LIANG Rui-hong, LIU Wei*,

2015, 17(5):  106-113.  DOI: 10.13304/j.nykjdb.2015.479

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Dynamic high-pressure microfluidization (DHPM) is an emerging physical modification technology. The structures and properties of macromolecules (proteins, enzymes, polysaccharides, dietary fiber, etc.) were changed when DHPM was applied to treat these food macromolecules. DHPM treatment can effectively improve protein solubility, stability, foaming, emulsifying properties, and antigenicity, increase enzyme activity and stability, and at the same time change their structure and conformation. DHPM treatment can also degrade non- starch polysaccharides, change their apparent viscosity, gelation property, water absorption, water retention, flow ability, and particle size, etc.. In addition, DHPM treatment can alter crystallinity, reduce the degree of retrogradation, improve gelatinization enthalpy and starch swelling property, etc.. In terms of dietary fiber, DHPM treatment can improve the hydration properties of dietary fiber, change its microtopography, increase the apparent viscosity, yield stress, and soluble dietary fiber content, etc.. Therefore, DHPM technology is a very effective method for modification of food macromolecules. This review could provide a theoretical reference for the development and modification of food macromolecules resources.

Effect of Non-thermal Processing Technology on the Structure and Function of Protein in Food

WANG Shuo, WANG Jun-ping, ZHANG Yan, GUO Jun

2015, 17(5):  114-120.  DOI: 10.13304/j.nykjdb.2015.521

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Non-thermal processing technology has been the hot spot in food processing field, owing to its characteristics in keeping food nutrition and safety. Protein is the major food substance and nutrition element. Any changes in its structure and functional characteristics would bring about great influence on food quality. This paper expounded the effects of ultra high pressure, ultrasonic, microwave, irradiation, 4 non-thermal processing methods on food protein structure and function, wishing to provide references for studies on non-thermal processing technology and practical production.

Research Advances in Enzyme Inactivation Mechanism by Microwave Radiation in Food

MIAO Wen-juan1, WEI Hai-yang2, XU Bin3*

2015, 17(5):  121-126.  DOI: 10.13304/j.nykjdb.2015.452

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Compared with the traditional thermal sterilization, microwave sterilization has advantages of high efficiency and less nutrient loss. In recent years, there are many research reports about microwave sterilization mechanism in domestic and abroad academic journals. However, there are great differences in the conclusions. This paper summarized comprehensively the recent research on enzyme inactivation mechanism by microwave from enzyme molecular structure and enzyme kinetics. The paper also expounded the development process of equipment used in microwave test for enzyme inactivation, so as to provide references for further studies on micro-mechanism of microwave sterilization in food enzymes.

Effect of Energy-gathered Pulsed Ultrasonic Pretreatment on Enzymatic Hydrolysis of Corn Gluten Meal

WANG Kai, MA Hai-le*, ZHANG Yan-yan, YE Xiao-fei

2015, 17(5):  127-133.  DOI: 10.13304/j.nykjdb.2015.454

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In order to research the improvement of enzymatic hydrolysis of corn gluten meal by energy-gathered pulsed ultrasonic pretreatment, on the basis of single factor experiment, this paper took the degree of hydrolysis (DH) and angiotensin-I converting enzyme (ACE) inhibition rate as evaluation indexes, and carried out orthogonal optimization test and gains the optimal ultrasonic pretreatment conditions: ultrasonic working frequency 40 kHz, initial temperature of liquid material 30℃, ultrasonic treatment time 15 min, per unit ultrasonic power 200 W/L, ultrasonic pulse work time 6 s and interpulse time 3 s. Under the optimal ultrasonic pretreatment conditions, hydrolysis degree and enzymatic hydrolysis product of ACE inhibition rate of corn gluten meal were 24.22% and 70.97%, respectively. Compared with those without pretreatment, the hydrolysis degree and ACE-inhibitory rate raised 9.39% and 11.08%, respectively. The results showed that ultrasonic pretreatment of corn gluten meal could not only promote its enzymatic hydrolysis, but also have a significant promotion on its enzymatic hydrolysis product of ACE inhibition activity.

Effect of Radio Frequency Heating and Blanching on Physicochemical Properties and Microstructure of Apple Slices

ZHANG Yong-di1, ZHOU Liang-fu1, LI Yu-kun1, MENG Chuang-ge1, LEI Yu-jie1, ZHAO H

2015, 17(5):  134-141.  DOI: 10.13304/j.nykjdb.2015.511

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Heating and blanching is an important process in apple and even fruit and vegetable processing industry. A pilot scale radio frequency (RF) heating system was used to heat apple slices under different gaps, to test heating curves and their uniformity, color, texture, activity of polyphenol oxidase (PPO) and weight changes. Micro-structure of apple slices was observed by scanning electron microscope (SEM) to reveal the mechanism of physical and chemical property changes in the process of RF blanching. The results indicated that the heating speed was the fastest at gap of 115 mm and the lowest at 125 mm. For temperature to raise from 22℃ to 95℃ 95 s and 140 s were needed, respectively. The temperature of apple slices was higher in the middle than the edges. The relative enzyme activity of PPO by RF blanching was due to the heating temperature and endurance time. With the increase of blanching temperature, the color-protecting effect became better, while the hardness of apple slices decreased. The cell damage degree of apple slices increased with the increase of temperature. The cell destruction of apple slices was smaller when temperature rose faster. The best RF heating conditions for apple slices was at the gap of 105 mm for 101 s.

Analysis on Changes of Flavor Substance During Late Fermentation Process of Chinese Rice Wine under Ultrasonic Circulation

MENG Xiang-yong1,2,3,4§, FENG Dong-yang 1,2§, MAO Jian1,2,3,4*, LIU Shuang-ping1

2015, 17(5):  142-150.  DOI: 10.13304/j.nykjdb.2015.456

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In order to find out the feasibility of industrialization of ultrasound treatment used in late fermentation process of Chinese rice wine, 30 L fermentor based on ultrasonic circulation was used for Chinese rice wine brewing. This paper studied the effect of ultrasonic assisted on the routine physics and chemistry index, such as alcohol content, total acid content and reducing sugar content during late fermentation process of Chinese rice wine. It also analyzed and compared the effect of ultrasonic assisted on the flavor substance, such as amino acids, organic acids, esters, aldehydes and higher alcohols. The results showed that there was no significant difference between the alcohol content of ultrasonic circulation treated samples and control samples at the end of fermentation. The study found that the contents of amino acid and organic acid of Chinese rice wine treated by ultrasonic circulation was higher than that of the control samples. While, the content of higher alcohols of Chinese rice wine treated by ultrasonic circulation was significant lower than that of the control samples. The results of clustering analysis indicated that ultrasonic circulation could enable the post-fermentation of Chinese rice wine to fermentation in advance. This research result revealed the feasibility of shortening fermentation cycle of Chinese rice wine by ultrasonic circulation.

Heating Regulation of Liquid Using Radio Frequency Heating

ZHAO Hui1, LEI Yu-jie2, HOU Quan2, ZHOU Liang-fu2, WANG Yun-yang2*

2015, 17(5):  151-156.  DOI: 10.13304/j.nykjdb.2015.512

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Radio frequency (RF) electromagnetic wave has the advantages of high penetration depth and fast heating speed, which could save time in food sterilization process and preserve the nutrient contents and high quality of food to the largest extent. Taking tap water and sodium chloride solution as material, this paper studied the affecting regulation of factors on electric fluid ratio of anode to grid and the liquid heating rate by RF heating. Those factors included liquids height-diameter ratio, liquid air ratio and electrical conductivity. The results showed that when the liquid air ration was changing, the electric fluid ratio of anode to grid of RF heating machine first went up, then reduced and reached the maximum value. The lager was the electric fluid ratio of anode to grid, the faster was the RF heating speed. The larger the height-diameter ration was, the quicker of RF heating was. When the electrical conductivity of liquid was around 900~1 000 μs/cm, the electric fluid ratio of anode to grid was relatively larger and the RF heating of liquid was also relatively faster.

The Influence of the Steam-microwave Heating on Fish Quality

HAN Zhong1, WANG Jun-cui1, TANG Xiang-wei2, GAO Wen-hong1*

2015, 17(5):  157-161.  DOI: 10.13304/j.nykjdb.2015.516

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Fish is one of the main meat resources in China. The moisture content of meat could be reduced by traditional microwave cooking method, thus the meat taste is spoiled. Combining microwave and steam, this paper studied the effects of steam microwave cooking on protein denaturation and various physical and chemical indexes of fish meat, aiming to optimize the technology and achieve the best quality of fish meat. The results showed that under steam-microwave condition, fish (about 45 g) was heated for about 100 s, then its protein began to denature. This study indicated that along with the increase of steam microwave cooking time, the moisture content reached its maximum on 105 s. Compared with the traditional microwave, steam microwave method successfully resolved the problem of severe water loss in food. Besides, the color change in fish meat was not obvious, and the elasticity decreased with the prolongation of cooking time. In a word, for 45 g fish, the optimum heating time was 100 s with steam microwave cooking. This result might be used as the basis for steam-microwave heating research.

Studies on Protective Effect of Corn Oligopeptide Against Acute Hepatic Injury of Mouse

LIU Xue-jiao, XU Wei-dong, MA Hai-le*, YAO Hao-jie, LUO Juan

2015, 17(5):  162-167.  DOI: 10.13304/j.nykjdb.2015.457

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To explore the protective effect of corn oligopeptide(COP) on CCl4-induced acute hepatic injury of mouse, this experiment carried out precautions for liver injury by intragastric infusion orally with COP daily dose of 200 mg/kg·d, 400 mg/kg·d, 800 mg/kg·d to mice. After 30 d, a dose of 10 mg/kg and 0.5% CCl4 was intragastric infused. 16 h later mouse liver index, the value of malondialdehyde (MDA), superoxide dismutase (SOD), glutathion peroxidase (GSH-px) and the contents of serum alanine aminotransferase (ALT) and glutamic-oxalacetic transaminease(AST) were measured. The pathological changes in hepatic tissues of each group were observed. The result showed that COP at high and middle doses could all significantly reduce the levels of AST, ALT and MDA of liver injured mouse caused by CCl4 (P<0.05) and improved their SOD and GSH-Px vigor (P<0.05). COP could also promote the recovery of mouse liver function, but had little effect on liver index. Under microscope, it could be observed that COP improved mouse hepatic injury. The above results indicated that COP can protect CCl4-induced acute liver damage of mouse.