为了避免食品电场加工中因电极使用而产生电化学反应造成食品污染和电极腐蚀的问题,采用交变磁通代替电极作为激励源,在果泥料液中诱导形成感应电场(induced electric field,IEF),实现对蓝莓果泥的IEF处理:分析激励电压、温度和时间对蓝莓果泥多酚氧化酶(polyphenol oxidase, PPO)和过氧化物酶(peroxidase, POD)活性及总花青素含量的影响。结果表明,100 V激励电压产生的IEF可减缓PPO和POD酶活的受热损失。150和250 V激励电压下,IEF与高温钝化PPO和POD具有协同作用。IEF可提高花青素分子的热稳定性且电场强度越高稳定作用越强。与未处理果泥相比,经85 ℃、250 V激励电压的IEF处理30 min的果泥总花青素含量得到最大提升(12.55%),PPO和POD可被完全灭活。该条件下获得的蓝莓果泥表观黏度与鲜榨果泥更为接近,且储藏期内(4 ℃,8周)的菌落总数维持在1 lg(CFU/mL)以下,显著低于常规热处理(0 V)和未经热处理的果泥。研究为蓝莓果泥的IEF处理提供了数据参考。
In order to avoid food contamination and electrode corrosion caused by electrochemical reaction adopting electrodes in prevailing electric field processing, induced electric field (IEF) processing of blueberry puree was conducted by applying magnetic flux to replace metal electrodes as excitation source. Effects of excitation voltage, temperature and processing time on polyphenol oxidase (PPO) activity, peroxidase (POD) activity and total anthocyanin content were investigated. Results indicated that IEF at excitation voltage of 100 V could maintain PPO and POD activity, but IEF at excitation voltages of 150 V and 250 V presented a synergistic effect with heat on the inactivation of the enzymes. IEF could enhance the thermal stability of anthocyanin molecules. Meanwhile, this stabilizing effect of IEF on anthocyanin was more significant when higher excitation voltage was applied. Compared with untreated blueberry puree, the IEF-treated sample had a maximum increase of 12.5% in anthocyanin content at the optimum conditions: excitation voltage of 250 V, temperature of 85 ℃ and processing time of 30 min, under which both PPO and POD were completely inactivated. Besides, the IEF-treated blueberry puree presented an apparent viscosity similar with that of the untreated blueberry puree. The total colonies number in IEF-treated blueberry (250 V, 85 ℃, 30 min) remained less than 1 lg CFU/mL during 8 weeks of storage at 4 ℃, which was significantly lower than that of the conventional heat-treated (0 V) and untreated samples. This study provides certain value reference for IEF processing of blueberry puree.
[1] BAKOWSKA A, KUCHARSKA A Z, OSZMIANSKI J. The effects of heating, UV irradiation, and storage on stability of the anthocyanin-polyphenol copigment complex[J]. Food Chemistry, 2003, 81(3): 349-355.
[2] NORBERTO S, SILVA S, MEIRELES M, et al. Blueberry anthocyanins in health promotion: a metabolic overview[J]. Journal of Function Foods, 2013, 5(4): 1 518-1 528.
[3] SIDDIQ M, DOLAN K D. Characterization of polyphenol oxidase from blueberry (Vaccinium corymbosum L.) [J]. Food Chemistry, 2017, 218: 216-220.
[4] VáMOS-VIGYáZó L, HAARD N F. Polyphenol oxidases and peroxidases in fruits and vegetables[J]. CRC Critical Reviews in Food Technology, 2009, 15(1): 49-127.
[5] 陶晓赟. 高压脉冲电场(PEF)对蓝莓汁品质及杀菌机理探究[D]. 北京:北京林业大学, 2015.
[6] ALMEIDA F D L, GOMES W F, CAVALCANTE R S, et al. Fructooligosaccharides integrity after atmospheric cold plasma and high-pressure processing of a functional orange juice[J]. Food Research International, 2017, 102: 282-290.
[7] DENG K, SERMENTMORENO V, WELTICHANES J, et al. Inactivation model and risk-analysis design for apple juice processing by high-pressure CO2[J]. Journal of Food Science & Technology, 2018, 55(1): 258-264.
[8] L′HOMME C, PUIGSERVER A, BIAGINI A. Effect of food-processing on the degradation of fructooligosaccharides in fruit[J]. Food Chemistry, 2003, 82(4):533-537.
[9] SIMPSON R, RAMíREZ C, BIRCHMEIER V, et al. Diffusion mechanisms during the osmotic dehydration of Granny Smith apples subjected to a moderate electric field[J]. Journal of Food Engineering, 2015, 166:204-211.
[10] ATHMASELVI K A, KUMAR C, POOJITHA P. Influence of temperature, voltage gradient and electrode on ascorbic acid degradation kinetics during ohmic heating of tropical fruit pulp[J]. Journal of Food Measurement & Characterization, 2016, 11(1):1-12.
[11] GOMATHY K, THANGAVEL K, BALAKRISHNAN M, et al. Effect of ohmic heating on the electrical conductivity, biochemical and rheological properties of papaya pulp[J]. Journal of Food Process Engineering, 2015, 38(4): 405-413.
[12] VANAMALA J, COBB G, LOAIZA J, et al. Ionizing radiation and marketing simulation on bioactive compounds and quality of grapefruit (Citrus paradisi c.v. Rio Red)[J]. Food Chemistry, 2007, 105(4): 1 404-1 411.
[13] PATARO G, BARCA G M J, DONSÌ G, et al. On the modeling of electrochemical phenomena at the electrode-solution interface in a PEF treatment chamber: Methodological approach to describe the phenomenon of metal release[J]. Journal of Food Engineering, 2015, 165:34-44.
[14] ROODENBURG B, MORREN J, BERG H E, et al. Metal release in a stainless steel Pulsed Electric Field (PEF) system: Part I. Effect of different pulse shapes; theory and experimental method [J]. Innovative Food Science & Emerging Technologies, 2005, 6(3): 337-345.
[15] YANG N, JIN Y, JIN Z, et al. Electric-field-assisted extraction of garlic polysaccharides via experimental transformer device[J]. Food & Bioprocess Technology, 2016, 9(9): 1 612-1 622.
[16] LI D, YANG N, JIN Y, et al. Continuous-flow electro-assisted acid hydrolysis of granular potato starch via inductive methodology[J]. Food Chemistry, 2017, 229: 57-65.
[17] QUEIROZ C, DA SILVA A J R, LOPES M L M, et al. Polyphenol oxidase activity, phenolic acid composition and browning in cashew apple (Anacardium occidentale, L.) after processing[J]. Food Chemistry, 2011, 125(1): 128-132.
[18] AYDIN N,KADIOGLU A. Changes in the chemical composition, polyphenol oxidase and peroxidase activities during development and ripening of medlar fruits (Mespilus germanica L.) [J]. Journal of Plant Physiology, 2001, 27(3-4): 85-92.
[19] 吴振, 李红,王勇德, 等. 不同热处理温度对蓝莓果汁在冷藏过程中多酚和黄酮含量的影响[J]. 食品与发酵工业, 2019, 45(17): 209-215.
[20] GB 4789.2—2016, 食品微生物菌落总数的测定[S]. 北京:中国标准出版社, 2016.
[21] ZHANG M, YANG N, GUO L, et al. Physicochemical properties of apple juice influenced by induced potential difference (induced electric field) during disposable continuous-flow treatment[J]. Journal of Food Engineering, 2018, 234: 108-116.
[22] RIENER J, NOCI F, CRONIN D A, et al. Combined effect of temperature and pulsed electric fields on apple juice peroxidase and polyphenoloxidase inactivation[J]. Food Chemistry, 2008, 109(2): 402-407.
[23] ZHONG K, WU J, WANG Z, et al. Inactivation kinetics and secondary structural change of PEF-treated POD and PPO[J]. Food Chemistry, 2007, 99(1): 115-123.
[24] MARTYNENKO A, CHEN Y. Degradation kinetics of total anthocyanins and formation of polymeric color in blueberry hydrothermodynamic (HTD) processing[J]. Journal of Food Engineering, 2016, 171: 44-51.
[25] MERCALI G D, JAESCHKE D P, TESSARO I C, et al. Degradation kinetics of anthocyanins in acerola pulp: comparison between ohmic and conventional heat treatment[J]. Food Chemistry, 2013, 136(2): 853-857.
[26] 郑炯, 张可珺, 曾瑞琪, 等. 高酯果胶对豌豆淀粉凝胶糊化及流变特性的影响[J]. 食品与发酵工业, 2019, 45(6): 91-96.
[27] 支东彦,练成,徐首红,等.随机共聚高分子凝胶溶胀和体积相变行为的分子热力学模型[J].化工学报, 2013, 64(1): 268-274.
[28] YI Z, BEI G, ZHANG M W, et al. Pulsed electric field processing effects on physicochemical properties, flavor compounds and microorganisms of longan juice[J]. Journal of Food Processing & Preservation, 2010, 34(6):1 121-1 138.
