采用低场核磁共振技术研究了固态渗透(solid osmotic dehydration, SSD)和液态渗透(liquid osmotic dehydration, LOD)过程中草莓水分的流失规律。结果表明,在糖渍72 h的过程中,2种糖渍方式下草莓水分含量均逐渐降低;在渗糖72 h时,SSD和LOD处理的草莓水分含量分别由91.83%下降至74.56%、79.90%。2种渗透方式的弛豫时间T22与T23值均伴随着渗透过程而变小,表示SSD和LOD都使得草莓中不易流动水和自由水的流动性减小;同时峰面积A22值均逐渐减小,表示2种渗透方式均减少了不易流动水的水分含量。然而在LOD处理过程中,草莓中自由水峰面积在渗透过程中呈下降趋势,但下降不显著(P＞0.05),同时弛豫时间T21峰位置逐渐右移,表示随着渗透时间的延长,草莓中结合水的流动性增强;相反,在SSD处理中,草莓中自由水峰面积在渗透72 h后显著下降(P＜0.05),相比0 h,下降幅度达55.35%,并伴随着渗透时间的延长,草莓中结合水的流动性减弱。另外,建立了低场核磁共振峰积分面积总和(A21+A22+A23)与草莓的含水率的线性拟合模型,线性关系显著(P＜0.05),R2均大于0.90,拟合效果较好。该研究从水分的角度探究了SSD和LOD对草莓的影响,为草莓干制作中渗糖方式的选择提供参考。
The law of water loss in strawberries during solid osmotic dehydration (SSD) and liquid osmotic dehydration (LOD) was studied by low-field nuclear magnetic resonance (LF-NMR). Results showed that the moisture content of strawberries decreased gradually during the 72 h osmotic dehydration. At the end of the osmotic dehydration procedures, the moisture content of the strawberries treated with SSD and LOD decreased from 91.83% to 74.56% and 79.90%, respectively. The relaxation time T22 and T23 values modes decreased with the osmotic dehydration process in both two osmotic dehydration methods, indicating that both SSD and LOD reduced the fluidity of immobilized water and free water in strawberries. At the same time, the peak area A22 value gradually decreased, indicating that the two infiltration methods reduced the moisture content of the immobilized water. During the LOD, the free water peak area in strawberries showed a downward trend during the permeation process, but the decline was not significant (P>0.05). At the same time, the position of the T21 peak gradually shifted to the right, indicating that with the prolongation of LOD time, the fluidity of bound water in strawberries increased. While the peak area of free water in strawberries decreased significantly after 72 h of infiltration (P<0.05) in the SSD treatment and, compared with 0 h, the decrease range was 55.35%, and the fluidity of bound water in strawberries was weakened with the extension of osmotic dehydration time. In addition, a linear fitting model between the sum of peak integral areas of low field NMR (A21+A22+A23) and the moisture content of strawberries was established. The linear relationship was significant (P<0.05). R2 was greater than 0.90, and the fitting effect was great. This study explored the effects of SSD and LOD on strawberries from the perspective of moisture and provided a reference for the selection of osmotic dehydration methods in preserved strawberries production.
[1] 李宇泽, 韩爱云.草莓保鲜技术的研究进展[J].农产品加工, 2021(6):88-90;93.
LI Y Z, HAN A Y.Research progress in strawberry storage preservation technology[J].Farm Products Processing, 2021(6):88-90;93.
[2] 张友峰, 邓洁红, 张华.草莓脯加工工艺优化研究[J].包装与食品机械, 2013, 31(5):15-18.
ZHANG Y F, DENG J H, ZHANG H.Optimization on processing technology of preserved strawberries[J].Packaging and Food Machinery, 2013, 31(5):15-18.
[3] 王俊涛. 固体糖渍对芒果脱水传质和品质的影响研究[D].南宁:广西大学, 2020.
WANG J T.Study on the effect of solid sugar cane on dehydration, mass transfer and quality of mango[D].Nanning:Guangxi University, 2020.
[4] 刘宗博, 张钟元, 李大婧, 等.双孢菇远红外干燥过程中内部水分的变化规律[J].食品科学, 2016, 37(9):82-86.
LIU Z B, ZHANG Z Y, LI D J, et al.Analysis of moisture change during far-infrared drying of Agaricus bisporus[J].Food Science, 2016, 37(9):82-86.
[5] ASSIS F R, MORAIS R M S C, MORAIS A M M B.Mass transfer in osmotic dehydration of food products:comparison between mathematical models[J].Food Engineering Reviews, 2016, 8(2):116-133.
[6] 姜佳惠. 草莓微波冻干过程及品质调控研究[D].无锡:江南大学, 2021.
JIANG J H.Study on the microwave freeze-drying process and quality control of strawberry[D].Wuxi:Jiangnan University, 2021.
[7] 吕为乔, 宋凯, 赵丹, 等.低场核磁共振分析在果蔬干燥中的应用进展[J].包装与食品机械, 2019, 37(3):47-50.
LYU W Q, SONG K, ZHAO D, et al.Advances in application of low-field nuclear magnetic resonance analysis and imaging in the field of drying of fruits and vegetables[J].Packaging and Food Machinery, 2019, 37(3):47-50.
[8] SANTAGAPITA P, LAGHI L, PANARESE V, et al.Modification of transverse NMR relaxation times and water diffusion coefficients of kiwifruit pericarp tissue subjected to osmotic dehydration[J].Food & Bioprocess Technology, 2013, 6(6):1434-1443.
[9] 王永瑞, 薛美芳, 罗瑞明, 等.羊肉烤制过程中水分的分布与迁移规律[J].中国食品学报, 2022, 22(3):297-308.
WANG Y R, XUE M F, LUO R M, et al.Moisture distribution and migration law of mutton during the roasting process[J].Journal of Chinese Institute of Food Science and Technology, 2022, 22(3):297-308.
[10] 王海鸥, 扶庆权, 陈守江, 等.不同护色预处理对牛蒡片真空冷冻干燥特性的影响[J].食品科学, 2017, 38(1):86-91.
WANG H O, FU Q Q, CHEN S J, et al. Effect of different color protection pretreatments on the vacuum freeze-drying characteristics of burdock (Arctium lappa L.) slices[J]. Food Science, 2017, 38(1):86-91.
[11] 张鹏飞. 桃片渗透脱水及联合干燥技术研究[D].北京:中国农业科学院, 2016.
ZHANG P F.Research on the osmotic dehydration and combined drying technology of peach cylinolers[D].Beijing:Chinese Academy of Agricultural Sciences, 2016.
[12] JIN X, VAN DER SMAN R G M, GERKEMA E, et al.Moisture distribution in broccoli:Measurements by MRI hot air drying experiments[J].Procedia Food Science, 2011, 1:640-646.
[13] CHENG X F, ZHANG M, ADHIKARI B, et al.Effect of power ultrasound and pulsed vacuum treatments on the dehydration kinetics, distribution, and status of water in osmotically dehydrated strawberry:A combined NMR and DSC study[J].Food and Bioprocess Technology, 2014, 7(10):2782-2792.
[14] 程新峰. 低频超声波辅助提高冷冻草莓加工全过程品质及效率的研究[D].无锡:江南大学, 2014.
CHENG X F.Study on quality and efficiency of the whole handling process of frozen strawberry enhanced by low-frequency ultrasound[D].Wuxi:Jiangnan University, 2014.
[15] TYLEWICZ U, PANARESE V, LAGHI L, et al.NMR and DSC water study during osmotic dehydration of Actinidia deliciosa and Actinidia chinensis kiwifruit[J].Food Biophysics, 2011, 6(2):327-333.
[16] LI L L, ZHANG M, BHANDARI B, et al.LF-NMR online detection of water dynamics in apple cubes during microwave vacuum drying[J].Drying Technology, 2018, 36(16):2006-2015.
[17] GENG S T, WANG H H, WANG X L, et al.A non-invasive NMR and MRI method to analyze the rehydration of dried sea cucumber[J].Analytical Methods, 2015, 7(6):2413-2419.
[18] RAO M A, COOLEY H J.Dynamic rheological measurement of structure development in high-methoxyl pectin/fructose gels[J].Journal of Food Science, 1993, 58(4):876-879.
[19] 刘施琳, 朱丰, 林圣楠, 等.琼脂凝胶强度及弛豫特性的研究[J].食品工业科技, 2017, 38(13):85-89;100.
LIU S L, ZHU F, LIN S N, et al.Research of strength and relaxation properties of agar gel[J].Science and Technology of Food Industry, 2017, 38(13):85-89;100.
[20] 程一鑫. 超声波对高甲氧基果胶NMR转折点蔗糖浓度及其结构的影响[D].南昌:南昌大学, 2014.
CHENG Y X.Effect of ultrasonic on NMR transition point of sucrose concentration and structure of high methoxy pectin[D]. Nanchang:Nanchang University, 2014.
[21] ALMRHAG O, GEORGE P, BANNIKOVA A, et al.Analysis on the effectiveness of co-solute on the network integrity of high methoxy pectin[J].Food Chemistry, 2012, 135(3):1455-1462.
[22] 曲文娟, 凡威, 熊婷, 等.核桃干燥过程的低场核磁共振横向驰豫分析[J].现代食品科技, 2021, 37(9):145-154;324.
QU W J, FAN W, XIONG T, et al.Lateral relaxation analysis of walnut drying process by low field nuclear magnetic resonance[J].Modern Food Science and Technology, 2021, 37(9):145-154;324.
[23] 张绪坤, 祝树森, 黄俭花, 等.用低场核磁分析胡萝卜切片干燥过程的内部水分变化[J].农业工程学报, 2012, 28(22):282-287.
ZHANG X K, ZHU S S, HUANG J H, et al.Analysis on internal moisture changes of carrot slices during drying process using low-field NMR[J].Transactions of the Chinese Society of Agricultural Engineering, 2012, 28(22):282-287.
[24] XU F F, JIN X, ZHANG L, et al.Investigation on water status and distribution in broccoli and the effects of drying on water status using NMR and MRI methods[J].Food Research International, 2017, 96:191-197.
