辛烯基琥珀酸菊粉酯的乳化及抑霉性能研究

以菊粉为参照,研究了取代度、添加量、冻融等因素对辛烯基琥珀酸菊粉酯乳化能力的影响,考察了辛烯基琥珀酸菊粉酯对扩展青霉、黑曲霉和黑根霉菌丝生长、孢子萌发和芽管伸长的抑制作用。试验结果表明:菊粉经辛烯基琥珀酸酐改性后具有良好的乳化性,其乳化能力随取代度(DS)和添加量的增加而增大。当辛烯基琥珀酸菊粉酯(DS=3.17×10-2)浓度为2.50%时,乳化液乳化效果和冻融稳定性良好,乳液颗粒大小一致、不聚集。抑菌实验表明辛烯基琥珀酸菊粉酯对扩展青霉、黑曲霉和黑根霉三种霉菌的最小抑菌浓度(MIC)分别为1.00%、4.00%和2.00%(m/V),其对扩展青霉、黑曲霉和黑根霉菌丝生长、孢子萌发和芽管伸长抑制作用随辛烯基琥珀酸菊粉酯浓度增加而增强。低于MIC浓度时,辛烯基琥珀酸菊粉酯对扩展青霉菌丝生长、孢子萌发和芽管伸长的抑制作用最强,其次是黑曲霉,对黑根霉的抑制作用较弱。     

Effects of pulsed electric field processing and storage on the quality and stability of single-strength orange juice

The effects of pulsed electric field (PEF) processing on microorganisms in orange juice and on the flavor and color of the juice during storage for 112 days at 4 and 22 degrees C were investigated. Single-strength orange juice was PEF processed at an electric field strength of 35 kV/cm for 59 micros and placed into sterilized glass bottles in a sanitary glove box. PEF-processed orange juice was microbiologically stable at 4 and 22 degrees C for 112 days. PEF processing resulted in significant increases in the hydrocarbons D-limonene, alpha-pinene, myrecene, and valencene (P < or = 0.05) but did not have any effect on octanal, decanal, ethyl butyrate, and linalool. The levels of hydrocarbon compounds did not change at 4 and 22 degrees C in 112 days. Octanal, decanal, ethyl butyrate, and linalool levels significantly decreased in 14 days at 4 degrees C and in 2 days at 22 degrees C. The decrease in these compounds did not have a significant effect on the sensory quality of the orange juice (P > or = 0.05). The microorganisms in PEF-processed orange juice, along with the flavor and color of the juice, remained stable at 4 degrees C for 112 days.     

Change regime of aroma active compounds in response to pulsed electric field treatment time,sour cherry juice apricot and peach nectars,and physical and sensory properties

Regime (direction, amount, rate, and pattern) of change in aroma active compounds was quantified as a function of four pulsed electric field (PEF) treatment times, three fruits, and 10 physical and eight sensory properties using the best-fit multiple linear regression (MLR) models. The PEF treatment times did not deteriorate 94% of the sensory properties and 70% of the physical properties and significantly change 57% of a total of 73 aroma active compounds detected for sour cherry juice, and apricot and peach nectars. The best performing MLR models belonged to 1-methyl-4-prop-1-en-2-ylcyclohexene as a function of fruit type, treatment time, and titratable acidity (= 49 mg/L; R_adj² = 95.7%; R_cv² = 94.9%) and to 2-[(2S,5S)-5-ethenyl-5-methyloxolan-2-yl]propan-2-ol as a function of fruit type, and treatment time (SE = 157 mg/L; R_adj² = 98.2%; R_cv² = 98.0%), respectively (n = 48; p < 0.001).Industrial relevancePulsed electric field (PEF) is one of the leading nonthermal food technologies especiallyfor processing of high acid low viscosity foods with satisfactory quality and microbial inactivation. It was shown in this study that PEF with different treatment times can successfully be applied in the pasteurization of sour cherry juice, and apricot and peach nectars with minimum loss of aroma active compounds and sensory and physical properties. Both PEF processing conditions and results can be used as a guide to determine PEF processing parameters for industrial scale processing of juices/nectars.     

Evaluation of Microbial Stability,Bioactive Compounds,Physicochemical Properties,and Consumer Acceptance of Pomegranate Juice Processed in a Commercial Scale Pulsed Electric Field System

This paper investigated the feasibility for pasteurizing raw (100 %) pomegranate juice in a commercial scale pulsed electric field (PEF) processing system. The juice was processed at 35 and 38 kV/cm for 281 μs at 55 °C with a flow rate of 100 L/h. Effect of PEF processing on microbial stability, color, °Brix, pH, sediment, antioxidant activity, total phenolic content, anthocyanin, and sensory properties after the treatments and during storage at 4 °C for 12 weeks were studied and compared to those of thermally processed juice. PEF treatments significantly (p?<?0.05) inhibited the growth of total aerobic bacteria, which remained at <2.5 log colony-forming units (CFU)/ml during the 12-week storage. No yeast and mold were detected (<0.69 log CFU/ml) in the PEF-treated juices during storage up to weeks 10 and 12, which is similar to the thermally processed juice. There were no significant differences in pH and °Brix values between the PEF processed juice and unprocessed juice. PEF processing did not alter the contents of total phenolics and anthocyanin as compared to unprocessed juice. PEF processing had significantly (p?<?0.05) less impact on the color of pomegranate juice than thermal processing. PEF-treated juice had the same consumer satisfaction scores as the unprocessed juice, which were significantly (p?<?0.05) higher than thermally processed juice samples. There was no significant difference between the two PEF treatments in all results. This study demonstrated that PEF technology extended microbial shelf-life and preserved the major quality and nutritional characteristics of pomegranate juice, and hence, is technically feasible for commercialization in the juice industry.     

高压脉冲电场技术在热带果汁加工中的应用前景

高压脉冲电场杀菌技术(简称PEF)是一项新兴的食品非热加工技术,在果蔬汁的加工中已显示出优越性.对国内外近年来关于PEF对果蔬汁中酶的影响、灭菌的效果及对其品质的影响等方面进行综述,分析热带果汁加工中存在的主要问题及PEF技术在热带果汁加工中的应用前景.     

PULSED ELECTRIC FIELD TREATMENT OF LIQUID WHOLE EGG INOCULATED WITH SALMONELLA ENTERITIDIS

The effects of pulsed electric fields (PEF) on the inactivation of Salmonella Enteritidis inoculated into liquid whole egg (LWE) and on the physical properties and the shelf-life of LWE were studied. PEF processing conditions were 1.2 mL/s flow rate, 200 pps frequency, 2.12 μs pulse duration, 25 kV/cm electric field strength, and 250 μs total treatment time. The PEF processing caused up to 1 log₁₀ cfu/mL reduction in S. Enteritidis population in LWE. The PEF-treated samples were subjected to heat at 55C for 3.5 min to inactivate the remaining bacteria without denaturing the LWE. The combination of PEF and heat treatments led to a 4.3 log₁₀ cfu/mL reduction in S. Enteritidis population (P < 0.05 ) and caused no significant change in viscosity, electrical conductivity, color, pH, and Brix, relative to control samples (P > 0.05 ). The PEF + 55C treated LWE samples presented significantly longer shelf-life at 4C compared with the control and heat treated samples (P < 0.05 ).     

Kinetics of Peroxidase Inactivation in Carrot Juice Treated with Pulsed Electric Fields

Peroxidase activity accounts for quality losses in many plant‐based foods. The paper provides insight into the inactivation kinetics of peroxidase (POD) in carrot juice treated with pulsed electric fields (PEF). Juice samples were subjected to electric field intensities of 20 to 35 kV/cm for 300 to 2000 μs. Up to 93% of the initial activity was inactivated after treating at 35 kV/cm for 1500 μs. POD activity inactivation correlated well with the increase in energy density input. A first‐order fractional conversion model best fitted the experimental results. Other kinetic approaches such as the Fermi's model can be used to estimate residual POD activity values in treated juices as a function of electric field strength. Practical Application : Pulsed electric fields (PEF) are a processing technology that can be used for the pasteurization of liquid food products. Peroxidase activity inhibition is required in carrot juices to prevent undesirable quality losses, such as discoloration, flavor changes, and loss of nutrients. The most significant processing parameters ruling POD inactivation in PEF‐treated carrot juice are identified and mathematical modeling of experimental data is conducted.     

Commercial-Scale Pulsed Electric Field Processing of Orange Juice

Effects of commercial‐scale pulsed electric field (PEF) processing on the microbial stability, ascorbic acid, flavor compounds, color, Brix, pH, and sensory properties of orange juice were studied and compared with those of thermal processing. Freshly squeezed orange juice was thermally processed at 90 °C for 90 s or processed by PEF at 40 kV/cm for 97 ms. Both thermally processed and PEF‐processed juices showed microbial shelf life at 4 °C for 196 d. PEF‐processed juice retained more ascorbic acid, flavor, and color than thermally processed juice (P<0.05). Sensory evaluation of texture, flavor, and overall acceptability were ranked highest for control juice, followed by PEF‐processed juice and then by thermally processed juice (P<0.01).     

Effects of Pulsed Electric Fields on the Activities of Microorganisms and Pectin Methyl Esterase in Orange Juice

Orange juice was treated with pulsed electric fields (PEF) in a pilot‐plant system to optimize PEF‐processing conditions for maximum microbial inactivation and to investigate the effects of PEF on pectin methyl esterase (PME) activity. Electric‐field strengths of 20,25,30, and 35 kV/cm and total treatment times of 39, 49, and 59 μs were used. Higher electric‐field strengths and longer total treatment times were more effective to inactivate microorganisms and PME (p < 0.05). PEF treatment of orange juice at 35 kV/cm for 59 μs caused 7–log reductions in total aerobic plate count and yeast and mold counts. About 90% of PME activity was inactivated by PEF treatment at 35 kV/cm for 59 μs. PEF‐treated orange juice at 35 kV/cm for 59 ms did not allow growth of microorganisms and recovery of PME at 4, 22, and 37 °C for 112 d.     

Inactivation of Pectin Methyl Esterase in Orange Juice by Pulsed Electric Fields

ABSTRACT: Pulsed electric fields (PEF) treatments were applied to nonpasteurized orange juice using a bench top PEF system to study effects of PEF on the activity of pectin methyl esterase (PME). Effects of electric strength on PME activity at a constant water bath temperature were studied using electric field strengths up to 35 kV/cm at 30 °C. Increase of electric field strength caused a significant inactivation of PME with increase in orange juice temperature ( p < 0.05). A thermal inactivation study showed that heating of orange juice at the same temperature as orange juice during PEF treatment was not effective as PEF treatment in inactivating PME. Effects of electric field strength at different water bath temperatures were studied using electric field strengths up to 25 kV/cm and water bath temperatures of 10–50 °C. Higher electric field strengths at higher water bath temperature were the more effective to inactivate PME. A combination of PEF treatment at 25 kV/cm and a water bath temperature of 50 °C caused 90% inactivation of PME.     

Activity of Electrolyzed Oxidizing Water Against Penicilium expansum in Suspension and on Wounded Apples

ABSTRACT: Spores of Penicillium expansum , the primary organism responsible for the occurrence of patulin in apple juice, were exposed to electrolyzed oxidizing (EO) water in an aqueous suspension and on wounded apples. Full-strength and 50% EO water decreased viable spore populations by greater than 4 and 2 log units, respectively. Although EO water did not prevent lesion formation on fruit previously inoculated with P. expansum , cross-contamination of wounded apples from decayed fruit or by direct addition of spores to a simulated dump tank was substantially reduced. EO water, therefore, has potential as an alternative to chlorine disinfectants for controlling infection of apples by P. expansum during handling and processing operations.     

Comparing equivalent thermal, high pressure and pulsed electric field processes for mild pasteurization of orange juice. Part I: Impact on overall quality attributes

Mild heat pasteurization, high pressure processing (HP) and pulsed electric field (PEF) processing of freshly squeezed orange juice were comparatively evaluated examining their impact on microbial load and quality parameters immediately after processing and during two months of storage. Microbial counts for treated juices were reduced beyond detectable levels immediately after processing and up to 2 months of refrigerated storage. Quality parameters such as pH, dry matter content and brix were not significantly different when comparing juices immediately after treatment and were, for all treatments, constant during storage time. Quality parameters related to pectinmethylesterase (PME) inactivation, like cloud stability and viscosity, were dependent on the specific treatments that were applied. Mild heat pasteurization was found to result in the most stable orange juice. Results for HP are nearly comparable to PEF except on cloud degradation, where a lower degradation rate was found for HP. For PEF, residual enzyme activity was clearly responsible for changes in viscosity and cloud stability during storage.

Industrial relevance

Development of mild processing technologies with a minimal impact on fruit juice can be considered as a true alternative of fresh fruit. The present work presents a fair comparison of mild heat treated, high pressure (HP) and pulsed electric field (PEF) processed orange juice as an alternative for thermal pasteurization. Orange juices were monitored during two months of storage.     

Pasteurization of mixed mandarin and Hallabong tangor juice using pulsed electric field processing combined with heat

Effects of pulsed electric filed (PEF) processing combined with heating (H-PEF processing) on the inactivation of microorganisms and the physicochemical properties of mixed mandarin and Hallabong tangor (MH) juice were studied. Using a pilot-scale PEF system, MH juice, pre-heated at 55 °C, was PEF-treated at 19 kV/cm of electric field and 170 kJ/L of specific energy and the juice, pre-heated at 70 °C, was PEF-treated at 16 kV/cm and 100 kJ/L or 12 kV/cm and 150 kJ/L. H-PEF processing at 70 °C–16 kV/cm–100 kJ/L reduced the aerobe, yeast/mold, and coliform counts of MH juice by 3.9, 4.3, and 0.8 log CFU/mL, respectively, without affecting the ascorbic acid concentration and antioxidant capacity of juice. H-PEF processing changed juice color and browning degree (p < 0.05), but not total soluble solid content or pH. By controlling initial juice temperature and electric field strength, H-PEF processing can be an effective pasteurization method for mixed juice with minimal changes in quality.     

THE USE OF PULSED ELECTRIC FIELDS IN PRODUCING JUICE FROM PAPRIKA (CAPSICUM ANNUUM L.)

Investigations were conducted on the impact of pulsed electric field (PEF) treatment on yield and some quality parameters of juice from paprika and results were compared to the results of juice obtained from enzymatically treated or untreated paprika mash. Paprika was comminuted mechanically after which the mash was subjected to either PEF (electric field strength = 1.7 kV/cm, pulse number = 30 and specific energy input per pulse = 0.5 kJ/kg) or a pectolytic enzyme preparation treatment. The extent of cell disintegration after the different pretreatments was monitored through cell disintegration index (Z_p) measurement prior to juice extraction through pressure (10 MPa for 4 min). Some quality parameters (pH, soluble solids (°Brix), total dry matter, color, total carotenoids as β-carotene and vitamin C) of the resultant juice samples were determined. PEF and enzyme treatments resulted in about 10% and 9% increase in juice yield, respectively. Juice from PEF treated paprika compared well in quality with enzyme treated or the untreated. And in some cases such as in color (redness, a value) of the juice, PEF treated had values (+ 18) higher than enzyme treated having + 15.5 and also in the amount of β-carotene extracted into the juice PEF treated juice had more than 60% as compared to about 44% from enzyme treated juice. The pH value for enzyme treated juice was lower than the others.     

脉冲电场技术应用于果蔬汁杀菌的研究进展

脉冲电场作为一种非热加工技术能保持果蔬汁的安全性、稳定性和新鲜度,同时具有处理时间短、温度低、能耗少等优势,是目前食品加工领域的研究热点,亦是最具应用潜力的技术之一。本文综述脉冲电场技术对果蔬汁的杀菌机理、影响因素、处理效果及与其他技术联合应用等方面,并进一步展望了脉冲电场在果蔬汁加工领域的应用前景。     

PULSED ELECTRIC FIELD INACTIVATION of MICROORGANISMS and PRESERVATION of QUALITY of CRANBERRY JUICE

Cranberry juice was treated either by high voltage pulsed electric field (PEF) at 20 kV/cm and 40 kV/cm for 50 and 150°s, or by thermal treatment at 90C for 90s. Higher field strength and longer treatment time reduced more viable microbial cells. the overall volatile profile of the juice was not affected by PEF treatment but it was affected by thermal treatment. No Significant difference in color was observed between the control and PEF treated samples. the application of 40kV/cm for 150 1ts resulted in no growth of molds and yeasts during storage at 22 and 4C, and no growth of aerobic bacteria during storage at 4C. PEF is an alternative process to thermal pasteurization for cranberry juice.     

Inactivation of Escherichia coli O157:H7 and Escherichia coli 8739 in apple juice by pulsed electric fields.

The effect of high voltage pulsed electric field (PEF) treatment on Escherichia coli O157:H7 and generic E. coli 8739 in apple juice was investigated. Fresh apple juice samples inoculated with E. coli O157:H7 and E. coli 8739 were treated by PEF with selected parameters including electric field strength, treatment time, and treatment temperature. Samples were exposed to bipolar pulses with electric field strengths of 30, 26, 22, and 18 kV/cm and total treatment times of 172, 144, 115, and 86 micros. A 5-log reduction in both cultures was determined by a standard nonselective medium spread plate laboratory procedure. Treatment temperature was kept below 35 degrees C. Results showed no difference in the sensitivities of E. coli O157:H7 and E. coli 8739 against PEF treatment. PEF is a promising technology for the inactivation of E. coli O157:H7 and E. coli 8739 in apple juice.     

苹果腐败霉菌的拮抗酵母菌筛选鉴定及拮抗机理初探

从苹果果皮中筛选出对引起苹果采后病害的扩展青霉(Penicillium expansum)、互隔交链格孢霉(Alternaria alternata)和黑曲霉(Aspergillus niger)具有拮抗作用的酵母菌,并初步研究其拮抗机理。结果表明:筛选得到两株可以同时拮抗三种腐败霉菌的拮抗酵母菌Y4和Y9,根据酵母菌菌落性状、生理生化特征并结合分子生物学的分析结果,鉴定为Candida railenensis和Aureobasidium pullulans,其中A.pullulans为类酵母真菌。C.railenensis的最佳拮抗浓度为109 CFU/mL,对P.expansum、A.alternata和A.niger的菌丝生长、孢子萌发和芽管生长均有显著(p<0.05)的抑制作用。扫描电镜观察到C.railenensis能够包围和吸附腐败霉菌孢子,与它们竞争营养与空间,此外还能够吸附P.expansum菌丝体与其直接作用。C.railenensis的主要抑病机理是营养与空间竞争,并且其生防效果的发挥是多种方式共同作用的综合结果。     

Effects of pulsed electric field processing on the quality and microbial inactivation of sour cherry juice

Pulsed electric fields (PEF) processing of sour cherry juice with the measurement of pH, ºBrix, titratable acidity, conductivity, colour (L*, a* and b*), nonenzymatic browning index, metal ion concentration, total ascorbic acid and total antocyanin content as well as microbial inactivation were searched in the study. Applied PEF treatment parameters did not cause any significant difference on measured properties of sour cherry juice (P > 0.05). On the other hand, inactivation of Escherichia coli O157:H7, Staphylococcus aureus, Listeria monocytogenes, Erwinia carotowora, Pseudomonas syringae subs. syringae, Botrytis cinerea and Penicillum expansum significantly increased with increased electric field strength and treatment time (P ≤ 0.05). It was revealed that PEF is a viable option to process sour cherry juice with significant amount of microbial inactivation and without adversely affecting important physical and quality parameters.     

Effects of Commercial-scale Pulsed Electric Field Processing on Flavor and Color of Tomato Juice

Effects of commercial‐scale pulsed electric field (PEF) processing on the flavor and color of tomato juice during storage at 4 deg;for 112 d were studied. Tomato juice was prepared by hot break at 88°C for 2 min and then thermally processed at 92° for 90 s or PEF processed at 40 kV/cm for 57 μs. The PEF‐processed tomato juice retained more flavor compounds of trans‐2‐hexenal, 2‐isobutylthiazole, cis‐3‐hexanol than thermally processed or unprocessed control tomato juice (P < 0.05). PEF‐processed juice had significantly lower nonenzymatic browning and higher redness than thermally processed or control juice (P < 0.05). Sensory evaluations indicated that the flavor of PEF‐processed juice was preferred to that of thermally processed juice (P < 0.01).