新型的过热蒸汽冲击烫漂（SSIB）提高了线辣椒的干燥速度和质量属性.docx
新型的过热蒸汽冲击烫漂（SSIB）提高了线辣椒的干燥速度和质量属性【中文6379字】
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新型的过热蒸汽冲击烫漂（SSIB）提高了线辣椒的干燥速度和质量属性【中文6379字】,中文6379字,新型,过热,蒸汽,冲击,ssib,提高,辣椒,干燥,速度,以及,质量,属性,中文
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Available at INFORMATION PROCESSING IN AGRICULTURE 4 (2017) 283290journal homepage: www. elsevie / locate/ inpaInnovative superheated steam impingement blanching (SSIB) enhances drying rate and quality attributes of line pepperXu-Hai Yang a, Qian Zhang a, Jun Wang b, Li-Zhen Deng b, Za Kan a,*a College of Mechanical and Electrical Engineering, Shihezi University, Shihezi 832001, Chinab College of Engineering, China Agricultural University, P.O. Box 194, 17 Qinghua Donglu, Beijing 100083, ChinaA R T I C L E I N F O Article history:Received 14 May 2017 Received in revised form 10 July 2017Accepted 13 July 2017Available online 27 September 2017Keywords:Line pepperHigh-humidity hot air impingement blanchingAir impingement drying Drying characteristics Quality attributesA B S T R A C T Blanching is an essential step before processing of agricultural products as it can inactivate enzymes that cause undesirable changes. In current work the effects of superheated steam impingement blanching (SSIB) time and temperature on drying characteristics and red pig- ments content of line pepper were investigated. Results showed that after a 3-min SSIB pre- treatment at 110 。C the pepper epidermis covered with wax coat was damaged. In addition, the drying time was extensively decreased and the loss of red pigments of dried products was reduced. Results showed that the whole drying process took place in the falling rate period, which indicated that diffusion was the dominant physical mechanism governing moisture movement in the samples. Therefore, the second Ficks law of diffusion was used to determine the effective moisture diffusivity (Deff) of line pepper, which increased from1.193 10 10 to 3.128 10 10 m2/s with increasing of the drying temperature and air veloc-ity. The drying activation energy (Ea) of pretreated samples was 34.31 kJ/mol, which decreased by 3% compared with the non-pretreatment group. The findings of this work indicate that SSIB is very promising pretreatment technique as it not only enhances drying process but also improves bioactive substance preservation of red pepper.。 2017 China Agricultural University. Publishing services by Elsevier B.V. This is an openaccess article under the CC BY-NC-ND license (/licenses/by-nc-nd/4.0/).1. IntroductionAs one of the most frequently consumed vegetable spices worldwide, line pepper (Capsicum annuum L.) is a rich source of health-promoting compounds such as vitamin C, red pig- ments, carotenoids 1,2. Frequent consumption of red pepper has many benefits for human health as it can promote glu- cose and lipid metabolism, stimulate the immune system, delay the aging, even prevent cancers 35.* Corresponding author.E-mail address: kanza_ (Z. Kan).Peer review under responsibility of China Agricultural University. /10.1016/j.inpa.2017.07.004The worldwide chillies and peppers production reached3.32 107 tons and China produced about 1.61 107 tonsaccording to Food and Agriculture Organization statistics for 2014 (FAO, 2016). However, due to its high moisture content and perishable tissue, the shelf life of fresh line pepper is very short 6. Drying is one of the most frequently used method for pepper preservation as it can remove water to the level at which microbial spoilage and deterioration reactions can be minimized 7.Currently, in China and other developing countries, the most common drying methods for peppers and other spices are the natural open sun drying and shade drying without technical aids 8. Although the capital investment is low2214-3173 。 2017 China Agricultural University. Publishing services by Elsevier B.V.This is an open access article under the CC BY-NC-ND license (/licenses/by-nc-nd/4.0/).289I n f o r m a t i o n P r o c e s s i n g i n A g r i c u l t u r e 4 ( 201 7) 28 3 290 NomenclatureA460spectrophotometer reading (absorbance)c Deffeffective moisture diffusivity (m2/s)DRdrying ratio (g moisture/g dry matter. h)D0 fcalibration factor of UV VIS spectrophotometerEa Hmoisture content (%, Wet basis)Gmsamples weight (kg)LMoinitial moisture content (kg/kg, dry basis)MR Mtmoisture content at any point in time (kg/kg, dryMebasis)rRuniversal gas constant (J/mol-K)tTtemperature (。C)Wttotal content of naturally coloring matter for linepepper powder (g)effective moisture diffusivity base (m2/s) activation energy (kJ/mol)dry matter weight (kg)the Flesh thickness of line pepper (m) moisture ratio (dimensionless)equilibrium moisture content (kg/kg, dry basis) correlation coefficientdrying time (h)samples weight at any time (kg)and the operation is simple, the natural open sun drying method still has several disadvantages. For example, during the natural open sun drying, the drying is not uniform and it needs to turn the products during the drying process, which is a tedious and laborious work. Moreover, peppers are sus- ceptible to re-adsorption of moisture during night or at bad weather, which may cause rewetting, or even spoilage of the product. In addition, as long exposure to solar radiation, the quality attributes may degrade seriously 9. It was observed that the carotenoid contents of pepper decreased as much as 80% during the natural open sun drying 10. In addition, line pepper is more difficult to dry than other biological mate- rials as it has a peculiar structure of a peel covered with a thin-layer of wax, which forms the main resistance to mois- ture transfer during dehydration process 1. It is very com- mon to use chemical pre-treatment methods to accelerate drying process 11. For example, Doymaz and Pala 12 used alkaline emulsion solutions to pretreat red pepper and found that pretreated peppers dried faster and obtained better color compared with the unpretreated samples. However, the chemical additives residue in the products may lead to food safety issues and how to deal with larger quantities of corro- sive chemicals is a challenge 13. Therefore, alternative pre- treatment and drying methods are necessary and very tempting for pepper drying in order to enhance the drying rate and product quality.In fact new pretreatment and drying methods for red pep- per drying have received extensive attention. In the case of red pepper pretreatment, Ramesh et al. 14 found that after 3 min steam blanching and then hot air drying, the dried red pepper contained more vitamin E and carotenoid as well as the drying rate was accelerated compared to unpretreated samples. Yong et al. 15 also observed that blanching and making perforations in the skin could enhance the drying rate of pepper by breaking the wax coat of pepper epidermis as well as keeping well the peppers color, nutrition and flavor. Vengaiah and Pandey 16 studied drying kinetics of peppers with or without blanching in different drying temperatures and air velocities and found that blanching could enhance drying rate.As considered red pepper drying, convective hot air drying is the most frequently used drying technique. For example, many researchers 1720,3 explored the effect of hot air dry-ing on drying kinetics and quality of peppers and found that the drying temperature is the most effective factor that affects the drying process of peppers compared with the air velocities and loading thickness. In addition, due to long time exposure to high air temperatures, the color, heat sensitive nutrients and rehydration capacity of the dried peppers were extensively reduced.Superheated steam impingement blanching (SSIB) is an innovative technology, which combines the advantages of superheated steam and impingement technology, resulting in a rapid, no waste water and efficient process 21. Xiao et al. 22 found that SSIB pretreatment could not only enhance the drying kinetics of sweet potato bars but also improve the quality of the final product in terms of color, rehydration ratio, and microstructure. In addition, Xiao et al. 23 observed that appropriately SSIB pretreatment can accelerate drying and improve the whiteness index of yam slices probably due to the absence of oxygen. Bai et al. 24 found that SSIB pretreatment is an effective pretreatment for Fuji apple quarters to inactivate PPO and meanwhile to maintain produce quality. Bai et al. 25 also observed that SSIB pretreatment could be a useful non-chemical pretreat- ment technology for seedless grape drying, which can not only enhance drying rate but also improve color parameters of seedless grape.Hot air impingement drying is an efficient drying tech- nology. With high heat transfer coefficient, impingement drying has the advantages such as better quality products, less energy consumption, shorter drying time compared to the conventional air drying 8. Recently, it has been applied in the field of food and agricultural products pro- cessing such as chestnut de-shelling and drying 26,27, rapeseeds drying 28, apricot drying 29, carrot cubes and seedless grapes drying 30,31, shrimp drying 32, herbs drying 3335, potato chips drying 36, Hami-melon slices drying 37.Therefore, this study applied SSIB and hot air impinge- ment drying to process the line pepper. The effect of the superheated steam impingement blanching (SSIB) pretreat- ment on drying characteristics and quality attributes of line pepper was explored. The findings of this work will contribute to better understand of the drying characteristics of line pep- per after being pretreated by SSIB.2. Materials and methods2.1. Material selectionFresh line peppers used in the present study were purchased from a local supermarket in Shihezi region in Xinjiang Pro- vince of China. The samples were checked carefully to discard the rotting and insect damage ones. To ensure the uniformity of the physical characteristics of experimental materials, the line pepper samples with the same size (average length and weight are 6.95 0.35 cm and 9.97 0.43 g, respectively) were selected. The average initial moisture content of the linepepper samples was 78.17 0.50% in wet basis or 3.58 kg/kg in dry basis, as determined by vacuum drying at 70 。C for24 h 2. The selected samples were stored in a refrigerator at 5 1 。C and 90% relative humidity for several hours before experiments.2.2. Experimental set-upThe schematic diagram of equipment used for superheated steam blanching and impingement drying was shown in Fig. 1, which was previously described by Xiao et al. 30. It was installed in the College of Engineering of China Agricul- tural University, Beijing, China. This apparatus basically con- sist of a steam generator to produce superheated steam, series of round nozzles in lines, an electric heater to heat the air, a centrifugal fan to supply the air flow and circulate the air flow, and a Proportional-Integral-Derivative (PID) con- troller (Omron, model E5CN, Tokyo, Japan) to control drying temperature. The distance between the round impingement nozzles and the up surface of line pepper is about 78 cm. Air velocity at the exit of impingement nozzle was measuredwith Founder Probe Anemometer (Founder, China) having an accuracy of 0.1 m/s. During all experiments the air outlet velocity was kept at 10.0 m/s. When doing SSIB experiments, the steam generator was opened, while during impingement drying experiments it was turned off.2.3. Sample preparation and treatmentThe line peppers were washed with tap water to remove the surface dust, and then blew with electronic fans to eliminate excess water on its surface. The line peppers were grouped into two groups: one was dried directly in hot air impinge- ment dryer without blanching, which was called the non- pretreatment control group (NP), the other one was pretreated by superheated steam impingement blanching (SSIB) and then dried by hot air impingement drying at the same condi- tion with NP samples. The SSIB pretreatment was carried out at the superheated steam temperature of 110 。C, relativehumidity of 40% and air velocity of 15 m/s for 3 min according to Wang et al. 1,2 and previous experiments. The drying experiments were performed at different drying temperatures (55, 60, 65, 70, 75, 80, and 85 。C) with constant air velocity of 15 m/s. After the dryer reached steady state conditions for the set points, the line peppers were spread in a single layer on stainless steel wire grid in the drying chamber. The sample weight was kept constant at 1000.50 g for all runs. Drying was continued until the moisture content of line pepper was dried to 0.11 kg/kg (d.b.) 1. The product was cooled and packed in low density polyethylene (LDPE) bags that wereheat-sealed. The experiments were replicated three times and the average of the moisture ratio at each value was used for drawing the drying curves.2.4. Mathematical modelling of drying curves and formulationThe moisture content of line pepper was calculated using the following equations: Wt GMt G1where Mt is the moisture content at any point in time (kg/kg, d.b.), Wt is the samples weight at drying time t point (kg), and G is the dry matter weight (kg).The moisture ratio (MR) of line pepper during drying exper- iments was calculated using Eq. (2) 38. Mt MeMMR 0 Me2Fig. 1 Schematic diagram of equipment used for superheated steam blanching and impingement drying.where Me is the equilibrium moisture content (kg/kg, d.b.), M0is the initial moisture content (kg/kg, d.b).As the values of the equilibrium moisture content Me are relatively small compared to M0 or Mt, the Me can be neglected and the moisture ratio can be simplified as Eq. (3) 39. Mt1. Superheated steam generator, 2. Temperature and windspeed controller, 3. Steam pipe, 4. Normally open valve,MR M035. Normally closed valve, 6. Return duct, 7. Centrifugal fan,8. Electric heating tube, 9. Blast pipe, 10. Airflow distribution chamber, 11. Temperature transducer, 12. HumidityThe drying rate (DR) of line pepper during drying experi-ments was obtained using Eq. (4).Mt1 Mt2transducer, 13. Drying chamber, 14. Material, 15. Pallet.DR t2 t14The effective moisture diffusivity (Deff) refers to the speed of moisture diffusivity in drying process, which can be described by the Ficks second law 40. Ficks second law can be simplified as Eq. (5) when drying time t is relatively long and within calculation accuracy range.2.6. Colour measurementsThe CIE Lab colour parameters (L*, a*, b*) were used to describe the colour of line pepper. L*, a*, b* were represent lightness, redness and yellowness, respectively. Fresh or dried pepper8ln MR ln p2 p2Deff t5L2were grinded, the dried powder were sifted by 28 mesh sieve. Then the colour parameters of grinded samples were mea-sured using acolorimeter (Shengmingyang Co., Beijing, China)where L is the flesh thickness of line pepper (m).The relation between Ea and Deff can be described by Arrhenius Equation 41 presented as Eq. (6).following the method described by Bai et al. 25. Total colour difference (DE) was calculated as Eq. (9):q 22 2E0Deff D0 exp R TEa273:156DE L0 L a a b0 b 9 where D0 is the effective moisture diffusivity base (m2/s), R iswhere DE is the difference between the colour of dried andfresh samples; L0, a0, and b0 are the color parameters of fresh*the universal gas constant with a value of 8.314 J/(mol-K), andT is the temperature (。C).Eq. (6) can be transfigured into Eq. (7) by taking the natural logarithm of both sides.samples; L*, a*, b* are the color parameters of dried pepper samples.2.7. Data analysisEa1ln Deff ln D0 R T 273:157It is known from Eq. (7) that the logarithm form of mois- ture effective diffusion coefficient (lnDeff) and the reciprocal of the temperature (1/(T + 273.15) showed a linear relation- ship. Therefore, the slope Ea/R can be gained by linear regression 42.2.5. Capsicum red pigments measurementThe capsicum red pigments content was an important quality index for the line pepper red evaluation. The red pigments content of dried line pepper was determined according to the method described by Wang et al. 1 with some modifica- tions. About 150200 g dried samples were taken and broke into powder with a grinder (RHP-600 A, Zhejiang Ronghao Industry & Trade Co., Ltd. China), then screened it through 28 meshes at the sieving rate of over 99%. Weighed 0.1 g sam- ple accurately, and shifted them into a 250 mL volumetric flask, adding 200 mL acetone. Put the flask on the vibrator with opaque device (Oscillating at 270300 times per minute) for 4 h. The acetone was used as control liquid, and a UVvis- ible spectrophotometer (TU-1810, Beijing Purkinje General Instrument Co., Ltd.) was used to measure light absorption value A at 460 nm. All experiments were carried out in triplicate.Total content of naturally coloring matter for line pepper powder is c, represented by gram of capsicum red pigments in dry sample per one kilogram. It is calculated by Eq. (8) 43.A460 f 2:5 105c 2250 100 - H m8The data were expressed as the mean of three determina- tions. And the data were analyzed by ANOVA and Duncans multiple-range test using SPSS statistics software (Version 21.0, SPSS Inc., Chicago, IL, USA). Statistical significance for differences was tested at 5% probability level (p 0.05) different among drying temperatures and between pretreatments, respectively.ness reducing was largely related to water reduction com- bined with Maillard reaction 3, which depended on both dry- ing temperature and drying time. The SSIB group had slightly higher lightness than NP, as PPO and POD were inactivated by SSIB 1. Similar to the change of red pigments, the values ofa* were relatively higher at medium drying temperatures(60, 65, 70, and 75 。C) than low (55 。C) or higher (80 and 85 。C) ones. Either longer drying time at lower drying tempera- ture, or the higher drying temperature caused the largerfrom 1.193 10 10 m2/s to 3.128 10 10 m2/s in the NP group, and it ranged from 1.285 10 10 m2/s to3.242 10 10 m2/s in the SSIB group. The drying activa-tion energy (Ea) of the SSIB group was 34.31 kJ/mol, which decreased by 3% compared to the NP group.(3) The loss of line pepper red pigments content of line peppers could be reduced in drying process. The light- ness of SSIB samples was higher than NP group.degradation of red pigments. The same phenomenon were found in the changes of b* and DE. overall, the moderate dry- ing temperatures (65, 70, and 75 。C) may much suitable forline pepper drying. The SSIB can improve the lightness, due to the reduction of drying time by SSIB. But there were no sig- nificant difference between NP and SSIB, when comes to red- ness, yellowness and total colour difference between fresh and dried samples.4. ConclusionsThe superheated steam impingement blanching had an sig- nificant influence on the drying characteristics, red pigments and colour for line pepper.(1) With a 3-min SSIB pretreatment, wax coat of pepper epidermis could be damaged. As a result, the perme- ability of pepper pericarp could be strengthened, heat and mass transfer could be improved, and the drying time could be shortened.(2) Results indicated that drying of line pepper took place in the falling rate period during the hot air impinge- ment drying process. Its whole drying process was con- trolled by the internal moisture diffusion. The linear regression model fitted well with drying kinetics. The Deff increased with drying temperatures. The Deff rangedAcknowledgementsThe authors wish to thank the National Natural Science Foun- dation of China (Grant No. 31360399) for the financial support.R E F E R E N C E S 1 Wang J, Fang XM, Mujumdar AS, Qian JY, Zhang Q, Yang XH, et al. Effect of high-humidity hot air impingement blanching (HHAIB) on drying and quality of red pepper (Capsicum annuum L.). Food Chem 2017;220:14552.2 Wang J, Yang XH, Mujumdar AS, Wang D, Zhao JH, Fang XM, et al. Effects of various blanching methods on weight loss, enzymes inactivation, phytochemical contents, antioxidant capacity, ultrastructure and drying kinetics of red bell pepper (Capsicum annuum L.). LWT-Food. Sci Technol 2017;77:33747.3 Vega-Ga lvez A, Di Scala K, Rodrguez K, Lemus-Mondaca R, Miranda M, Lo pez J, et al. Effect of air-drying temperature on physico-chemical properties, antioxidant capacity, colour and total phenolic content of red pepper (Capsicum annuum, L. var. Hungarian). Food Chem 2009;117(4):64753.4 Yoshioka M, St-Pierre S, Suzuki M, Tremblay A. Effects of red pepper added to high-fat and high-carbohydrate meals on energy metabolism and substrate utilization in Japanese women. Br J Nutr 1998;80(06):50310.5 Surh YJ, Lee E, Lee JM. Chemoprotective properties of some pungent ingredients present in red pepper and ginger. Mutat Res/Fund Mol Mech Mutagenesis 1998;402(1):25967.6 Kaleemullah S, Kailappan R. Modelling of thin-layer drying kinetics of red chillies. J Food Eng 2006;76(10):5317.7 Gupta P, Ahmed J, Shivhare US, Raghavan GSV. Drying characteristics of red chilli. Drying Technol 2002;20 (10):197587.8 Xiao HW, Mujumdar AS. Chapter 12: Impingement drying: applications and future trends. In Drying Technologies for Foods: Fundamentals & Applications (ISBN978-938-14-5074-1) (2014) edited by Prabhat K. Nema, Barjiinder Pal Kaur, and Arun S. Mujumdar. Printed in December 2014 by New India Publishing Agency, New Delhi, India. (pp. 279299).9 Saengrayap R, Tansakul A, Mittal GS. Effect of far-infrared radiation assisted microwave-vacuum drying on drying characteristics and quality of red chilli. J Food Sci Technol 2015;52(5):2610.10 Topuz A, Ozdemir F. Influence of gamma-irradiation and storage on the carotenoids of sun-dried and dehydrated paprika. J Agric Food Chem 2003;51:49727.11 Antal T, Kerekes B, Sikolya L. Physical properties of freeze dried vegetables by different thermal and chemical pre- treatments. Files. antaldr. webnode. Hu; 2013.12 Doymaz I, Pala M. Hot-air drying characteristics of red pepper. J Food Eng 2002;55(4):3315.13 Xie L, Mujumdar AS, Fang XM, Wang J, Dai JW, Du ZL, et al. Far-infrared radiation heating assisted pulsed vacuum drying (FIR-PVD) of wolfberry (Lycium barbarum, L.): effects on drying kinetics and quality attributes. Food Bioprod Process 2017:32031.14 Ramesh MN, Wolf W, Tevini D, Jung G. Influence of processing parameters on the drying of spice paprika. J Food Eng 2001;49:6372.15 Yong CK, Islam MdR, Mujumdar AS. Mechanical means of enhancing drying rates: effect on drying kinetics and quality. Drying Technol 2006;24(3):397404.16 Vengaiah PC, Pandey JP. Dehydration kinetics of sweet pepper (Capsicum annum L.). J Food Eng 2007;81:2826.17 Kaleemullah S, Kailappan R. Drying kinetics of red chillies in a rotary dryer. Biosys Eng 2005;92(1):1523.18 Arora S, Bharti S, Sehgal VK. Convective drying kinetics of red chillies. Drying Technol 2006;24(2):18993.19 Jianjun Zhang, Yongchang Ma, Haixia Wang, Yan Zheng. Experimental research of optimizing process on hot-air drying properties of capsicum. Trans CSAM 2007;38(12):2234 in Chinese with English abstract.20 Vega-Ga lvez A, Lemusmondaca R, Bilbaosa inz C, Fito P, Andres A. Effect of air drying temperature on the quality of rehydrated dried red bell pepper (var. lamuyo). J Food Eng 2008;85(1):4250.21 Xiao HW, Law CL, Sun DW, Gao ZJ. Color change kinetics of American ginseng (Panax quinquefolium) slices during air impingement drying. Drying Technol 2014;32(4):41827.22 Xiao HW, Lin H, Yao XD, Du ZL, Lou Z, Gao ZJ. Effects of different pretreatments on drying kinetics and quality of sweet potato bars undergoing air impingement drying. Int J Food Eng 2009;5(5). Article 5.23 Xiao HW, Deng LZ, El-Mashad HM, Yang XH, Mujumdar AS, Gao ZJ. Recent developments and trends in thermal blanching-a comprehensive review. Inform Process Agric 2017;4(2):10127.24 Bai JW, Gao ZJ, Xiao HW, Wang XT, Zhang Q. Polyphenol oxidase inactivation and vitamin C degradation kinetics of Fuji apple quarters by high humidity air impingement blanching. Int J Food Sci Technol 2013;48:113541.25 Bai JW, Sun DW, Xiao HW, Mujumdar AS, Gao ZJ. Novel superheated steam impingement blanching (SSIB)pretreatment enhances drying kinetics and color attributes of seedless grapes. Innovative Food Sci Emerging Technol 2013;20:2307.26 Gao ZJ, Lin H, Xiao HW. Air-impingement de-shelling of chestnuts (C. mollisima): process parameter optimization. Int J Food Eng 2008;4(2). Article 14.27 Lou Z, Xiao HW, Wang XT, Li W, Sun XC, Gao ZJ. Air impingement drying characteristics and processing of Chestnut. Trans CSAE 2010;26(11):36873 in Chinese with English abstract.28 Go mez JE, Melo DL, Bo rquez RM, Canales ER. Computational study of impingement jet drying of seeds using superheated steam based on kinetic theory of granular flow. Drying Technol 2009;27:117182.29 Xiao HW, Zhang S, Bai JW, Fang XM, Zhang Z, Gao ZJ. Air impingement drying
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