- Email: [email protected]
Effect of high oxygen pretreatment of whole tuber on anti-browning of fresh-cut potato slices during storage
Food Chemistry 301 (2019) 125287
Contents lists available at ScienceDirect
Food Chemistry journal homepage: www.elsevier.com/locate/foodchem
Short communication
Effect of high oxygen pretreatment of whole tuber on anti-browning of freshcut potato slices during storage
T
⁎
Xia Liu , Ting Wang, Yuzhuo Lu, Qian Yang, Yuan Li, Xudong Deng, Ying Liu, Xinru Du, Liping Qiao, Jiaxuan Zheng State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Food Nutrition and Safety, Ministry of Education of China, College of Food Engineering and Biotechnology, Tianjin University of Science &Technology, Tianjin 300457, PR China
A R T I C LE I N FO
A B S T R A C T
Keywords: High oxygen pretreatment Enzymatic browning Fresh-cut potato
The surface browning usually occurs on fresh-cut potato during storage. The effect of short-time high oxygen pretreatment on anti-browning of fresh-cut potato slices was investigated. The whole potato tubers were firstly immersed in the oxygen concentration of 21%, 60% and 80% for 20 min. Then, the potatoes were peeled, cut and stored at 4 °C for 8 days. The results showed that the short-time 80% oxygen pretreatment possessed significantly anti-browning effect by retarding the increase of polyphenol oxidase (PPO) activity and the accumulation of malondialdehyde (MDA) content, maintaining the cell integrity. Meanwhile, the 80% oxygen treatment could increase the activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD), and the total phenolic content. Importantly, the 80% oxygen treatment could effectively improve the antioxidant capacity. Overall, all results suggest that the short-time high oxygen pretreatment holds great promise on anti-browning of fresh-cut potato.
1. Introduction Fresh-cut fruit and vegetable has shown a growing market prospect with the acceleration of people’s pace of life because of their convenience, healthfulness and freshness (Kim, Kim, Chung, & Moon, 2014). Potato (Solanum tuberosum L.) is the main product of fresh-cut fruit and vegetable industry (Ma, Zhang, Bhandari, & Gao, 2017). However, the surface browning usually occurs on fresh-cut potato during storage, which leads to the poor appearance, a lower consumer's purchase decision, and a shorter shelf-life (Liu et al., 2019). Hence, the prevention of surface browning has been a focus on the fresh cutting industry’s field in recent decades. It is well known that the surface browning is mainly brought by enzymatic browning, a reaction that the phenolic compounds produce quinones and then these quinones transform into pigments when oxygen is present (Cantos, Tudela, Gil, & Espín, 2002; Moon et al., 2018; Supapvanich, Mitrsang, Srinorkham, Boonyaritthongchai, & Wongs-Aree, 2016). Polyphenol oxidase (PPO) is the key enzyme in the melanogenesis pathway of enzymatic browning, which catalyzes not only the hydroxylation of monophenols to diphenols but also the oxidation of diphenols to quinones (Martinez & Whitaker, 1995).
Meanwhile, the peroxidase (POD) is another important oxidative enzyme by the formation of free radical species during browning (McEvily, Iyengar, & Otwell, 1992). As well as POD, phenylalanine ammonia-lyase (PAL), an important wound-induced enzyme, is also involved in enzymatic browning. PAL catalyzes the browning substances formation of phenolic components by the L-phenylalanine pathway (Assis, Maldonado, Muñoz, Escribano, & Merodio, 2001; Cantos et al., 2002). Therefore, the regulation of PPO, POD and PAL activities is an crucial target for many anti-browning strategies (Liu et al., 2018, 2019). In recent years, many methods of anti-browning and keeping quality of fresh-cut products have been reported, including fumigation treatment (ozone, chlorine dioxide, pressurized argon and nitrogen), preventing oxygen contact treatment (chitosan, plant protein isolate films, modified atmosphere packaging), antioxidant and related enzyme inhibitor treatment (citric acid, ascorbic acid, 24-epibrassinolide, amino acid, purslane extract, cod peptides and swertiajaponin), and some physical- based methods (UV-C, heating combining modified atmosphere packaging) (Azevedo et al., 2018; Calder, Skonberg, DavisDentici, Hughes, & Bolton, 2011; Gao, Chai, Cheng, & Cao, 2017; Goyeneche, Agueero, Roura, & Di Scala, 2014; Li, Jiang, Li, Tang, &
Abbreviations: PPO, polyphenol oxidase; POD, peroxidase; PAL, phenylalamine ammonia lyase; MDA, malondialdehyde ⁎ Correspondence author. E-mail address: [email protected] (X. Liu). https://doi.org/10.1016/j.foodchem.2019.125287 Received 22 May 2019; Received in revised form 28 July 2019; Accepted 28 July 2019 Available online 29 July 2019 0308-8146/ © 2019 Elsevier Ltd. All rights reserved.
Food Chemistry 301 (2019) 125287
X. Liu, et al.
& Li, 2016). Firstly, the mixture of ground fresh-cut potatoes slices (2.0 g) and 60% ethanol extract (5.0 mL) were centrifuged at 10,000×g for 10 min. Then the supernatant (0.25 mL), distilled water (5.0 mL), Na2CO3 solution (0.80 mL) and folin-phenol reagent (0.25 mL) were mixed well at volumetric flask (25 mL) and then react for 30 min in dark place. Finally, the absorbance value was measured at 760 nm. The total phenolic content was expressed as g kg−1 in fresh weight using gallic acid standard solution as blank control.
Yun, 2014; Liu et al., 2018, 2019; Moon et al., 2018; Shen, Zhang, Devahastin, & Guo, 2019; Wang et al., 2019). As a whole, most of them were chemical-based treatments that raised the safety concerns among consumers, or made the fresh-cut processing relatively complicated. High oxygen treatment has been used during preservation of fruits and vegetables, which promoted the increases of antioxidant capacity and total phenolic contents by the > 60% O2 concentration continuously treatment (Zheng, Wang, Wang, & Zheng, 2003). Continuous treatment of 60%–100% oxygen also could significantly inhibit fruit decay, the rates of respiration and ethylene production, and also inactivate pathogens activity (Allende, Luo, McEvoy, Artes, & Wang, 2004; Geysen, Escalona, Verlinden, & Nicolai, 2007; Kader & BenYehoshua, 2000; Wszelaki & Mitcham, 2000; Zheng, Yang, & Chen, 2008). The increase of antioxidant capacity, which was induced by superatmospheric oxygen may result from the Redox biological system and the integrity of the membrane (Oms-Oliu, Odriozola-Serrano, Soliva-Fortuny, & Martin-Belloso, 2008; Van der Steen, Jacxsens, Devlieghere, & Debevere, 2002). Moreover, as an abiotic stress, the high oxygen treatment inevitably regulates the reactive oxygen species (ROS) and Redox biological system (Li et al., 2014; Odriozola-Serrano, Oms-Oliu, Soliva-Fortuny, & Martín-Belloso, 2009; Perez & Sanz, 2001). However, there is little report on the effect of short-time high oxygen pretreatment for whole potato tuber on the browning of fresh-cut potato by initiating the resistance. In this research, the effect of short-time high oxygen pretreatment of whole tuber as a pre-stimulation on antibrowning were evaluated by investigating the activity of PPO, POD and PAL, total phenol content, membrane permeability, malondialdehyde content (MDA) and antioxidant capacity during fresh-cut potato slices storage at 4 °C.
2.4. Membrane permeability The relative electrical conductivity was measured according to existing test methods for expressing membrane permeability (Xu et al., 2009). Firstly, the uniform discs of 10 mm diameter was obtained from the samples by a hole puncher. Secondly, for removing the electrolytes adhering of the potato slices surface, deionized water was used to wash these discs for three times. Then after drying by filter paper, these discs with deionized water (20 mL) were boiled for 15 min. The relative electrical conductivity values were measured by a conductometer (DDS11A type, Shanghai, China). 2.5. MDA content The fresh potatoes (5.0 g), trichloroacetic acid (10.0 mL, 100 g L−1) were mixed and ground together with some quartz sand. After centrifuging at 10,000×g for 20 min, the supernatant (3.0 mL) and thiobarbituric acid solution (3.0 mL, 0.6%, w/w) was blend. Then, the mixture was boiled for 15 min. After cooling to room temperature, the mixture was centrifuged at 10,000×g for 15 min. Finally, the absorbance of the supernatant was measured at 450 nm, 532 nm and 600 nm. The expression of MDA content of fresh sample weight was µmol kg−1 (Dong, Wrolstad, & Sugar, 2000).
2. Materials and methods 2.1. Material and sample preparation
2.6. The activity of PPO The potatoes (S. tuberosum, cv Netherlands 7) were purchased from a farm market in Tianjin, China. The fresh potatoes with uniform size and no mechanical damage, pests and diseases were screened. Then, the selected potatoes were placed in a sealed jar, which connected with the gas control device for high oxygen pretreatment. Then, the original air in the jar was discharged by N2, and then filled with concentrations of 60% and 80% oxygen for 20 min, respectively. And a group of potatoes was immersed in air condition (oxygen concentration 21%) as blank control. The gas concentration was checked regularly with an O2/CO2 analyzer (PBI-Dansensor A/S, Danish, Ringsted, Denmark). The selected potatoes were cleaned, peeled and sliced to 0.5 cm thick slices. For removing starch, the potato slices were washed with water, dried with gauze and packed into the ziplock bags (polyethylene, PE) (Ali, El-Gizawy, El-Bassiouny, & Saleh, 2016). Finally, all the samples were stored at 4 ± 1 °C for 8 days. For each treatment, three replicates were analyzed and investigated in the next experiment for every two days.
The PPO activity was determined according to the previously reported method (Fu, Zhang, Wang, & Du, 2007). Firstly, fresh-cut potatoes slices (2 g) with acetic acid-sodium acetate buffer (5.0 mL, 0.1 mol L−1, pH 5.5) were ground. After centrifuging at 10,000×g for 30 min, supernatant (100 mL), acetic acid-sodium acetate buffer (4 mL, 0.05 mol L−1, pH 5.5) and catechol solution (1 mL, 0.05 mol L−1) were rapidly mixed and measured the absorbance value at 420 nm. The was expressed in of fresh weight. The expression of PPO activity of fresh sample weight was U g−1. 2.7. The activity of POD The activity of POD was assayed according to the reported method (Li, Li, Fan, Tang, & Yun, 2012). Firstly, the mixture of ground fresh potato slices (2 g) and acetic acid-sodium acetate buffer (5.0 mL, 0.1 mol L−1, pH 5.5) were centrifuged at 10,000×g for 30 min. Then, supernatant (5.0 mL) and guaiacol solution (5.0 mL, 0.025 mol L−1) were mixed and rapidly added H2O2 solution (0.2 mL, 0.5 mmol−1), then immediately measured the absorbance value at 470 nm. The expression of POD activity of fresh sample weight was U g−1.
2.2. Measurement of color The surface color was measured by a chromameter (CM-3600d, Konica Minolta, Japan), which provided lightness (L*), reddish–greenish (a*) and yellowish–bluish (b*) values (Wang et al., 2015). The comprehensive evaluation index of color difference (ΔE*) was compared with the initial time, which calculated according to the following formula: ΔE* .
2.8. The activity of PAL The activity of PAL was determined according to the reported method (Mishra, Gautam, & Sharma, 2012). Firstly, the mixture of ground fresh-cut potatoes slices (1 g) and boric acid buffer (5.0 mL, PH 8.8, 0.05 mol L−1) were centrifuged at 10,000×g for 30 min. Secondly, after boric acid buffer (3.0 mL, PH 8.8, 0.05 mol L−1) and L-phenylalanine (0.5 mL, 0.02 mol L−1) blending and incubating at 37 °C for 10 min, the supernatant (0.5 mL) was quickly added. Then, the initial absorbance value was measured at 470 nm. Finally, after the whole
2.3. Total phenolic content The content of total phenols was measured according to the FolinCiocalteu procedure with slight modification (Cantos et al., 2002; Wills 2
Food Chemistry 301 (2019) 125287
X. Liu, et al.
may be because high oxygen pretreatment induced the peroxidization reaction. However, after that, the MDA content of high oxygen pretreatment was significantly lower than control. In term of the overall changes of plasma membrane permeability, which was expressed by relative electrical conductivity, the greater membrane permeability, the greater membrane damage degree. From Fig. 2B, the relative electrical conductivity was lower than control not only for 60% high oxygen but also for 80% high oxygen samples after 2 d storage. In addition, the antioxidant capacity of fresh-cut potato slices was measured by α,αdiphenyl-β-picrylhydrazyl (DPPH) free radical scavenging rate (Fig. 2C). The highest rates of free radical scavenging rate were observed in 80% short-time oxygen pretreatment during the entire storage time at 4 °C. Overall, the 80% oxygen short-term pretreatment could significantly delay the damage of cell membrane, retard the accumulation of MDA, and induced the antioxidant capacity, which was consistent with the effects of short-term anoxia treatment on browning of fresh-cut Chinese water chestnut (You et al., 2012). As a kind of abiotic stress, the high oxygen pretreatment may provoke stress response not only causing the imbalance of physiological metabolic but also resulting in the production of reactive oxygen species (ROS) (Jacobo-Velazquez, Martinez-Hernandez, Rodriguez, Cao, & Cisneros-Zevallos, 2011). On the other hand, ROS mediated signal pathway and secondary messengers are activated, especially triggered serial redox reactions. Here, the samples of 80% and 60% oxygen short-time treatment had been induced systemic resistance (ISR) due to activate Redox system before wounding stress of peeling and cutting. Then, many domino effects of wounding stress would be early launch resulting anti-browning, which maybe the same mechanism of hypoxia by ISR (Paul et al., 2016).
mixture incubating at 37 °C for 60 min, the absorbance value at 470 nm was measured. The expression of PAL activity of fresh sample weight was U g−1. 2.9. Antioxidant capacity The antioxidant activity was expressed as the free radical scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (Jeong, Nam, Lee, & Lee, 2011). The fresh potato slices were ground and centrifuged at 10,000×g for 15 min at 4 °C. Then, the supernatant was taken for reserve. Firstly, 4.0 mL DPPH solution (257.7 mg L−1) and 1 mL ethanol (95%, w/w) were mixed and measured the absorbance value at 517 nm after 30 min reaction (A0). Then, 1 mL supernatant and 4 mL ethanol (95%, w/w) were mixed and measured the absorbance value at 517 nm after 30 min reaction (Ar). Finally, 1 mL supernatant, 4 mL DPPH solution (257.7 mg L−1) were mixed and obtained the absorbance value at 517 nm after 30 min reaction (As). The final DPPH values were calculated by the following formula: DPPH % = {1 − (As − Ar)/A0} × 100. 2.10. Statistical analysis All treatment samples were carried out in triplicate. One-way analysis of variance (ANOVA) was used to analyze the experimental data by SPSS13.0. Data expressed as mean ± SD, and P ≤ 0.05 was considered to be significant by LSD test. 3. Results and discussion 3.1. Effect of high oxygen pretreatment to whole tuber on surface color and overall visual quality
3.3. The activity of PPO, POD and PAL and total phenolic content The browning reaction of fresh-cut fruit and vegetable is very complex. The substrate levels, cell damage degree, enzyme activity and so on all could affect the reaction process of browning in fresh-cut fruit and vegetable (Wang et al., 2019). The enzyme activity change of PPO, POD and PAL, and the total phenolic content change were shown in Fig. 3 during fresh-cut potato slices storage. Interestingly, the inductive effect of high oxygen pretreatment for the whole potato on the activity of PPO and POD, browning reaction-related enzymes were inconsistent (Fig. 3A and B). Fig. 3A showed an overall increasing trend for the activity of PPO with the storage time. Except for the first two days, the activity of PPO were significantly inhibited by short-time high oxygen pretreatment. And, the treatment with 80% oxygen pretreatment possessed the lowest activity after 4 d storage. Different from PPO, the activity of POD with high oxygen pretreated expressed higher catalysis activity than control during the whole storage period. Oddly, the activity of PAL, the primary enzyme involving in the browning substrate synthesis (phenolic compounds), was conflicted between 60% and 80% high oxygen pretreatment (Fig. 3C). The upregulated activity of PAL, but down-regulated activity was significantly come out in samples with 80% high oxygen pretreatment and 60% high oxygen pretreatment, respectively. The results were consistent with the reported results of continuously superatmospheric oxygen treatment (Geysen et al., 2007; Kader & Ben-Yehoshua, 2000; Zheng et al., 2003, 2008). As well as the PAL activity, the total phenolic content of potato slices with 80% oxygen treated was significantly higher than control, but the phenolic content with 60% oxygen treatment was lower than control at the first 4 d storage (Fig. 3D). Meanwhile, after 4 d storage, the total phenolic content tended to be similar in different groups but an increase in samples with 80% oxygen treated at 8 d storage. Together, the activities of PAL were increased at first 4 d because of the initiation of inducible resistance, but decreased after 4 d storage maybe because of the enough total phenolic content accumulation. Here, the results showed that the related enzyme activities, including PPO, POD and PAL, could be regulated by moderate oxygen
The effect of high oxygen pretreatment to whole tuber on the surface color and overall visual quality was investigated (Fig. 1). From the Fig. 1A, the effect of anti-browning was the most obvious on the overall visual quality in samples with 80% oxygen pretreatment, but the slight anti-browning effect of 60% oxygen pretreatment than the control group during the entire 8 days storage at 4 °C. In particular, the 80% oxygen pretreatment significantly maintained the yellow color, it was similar to the initial color even after 6 d storage (Fig. 1A). Like the overall visual quality, the continual increase in the a* values (red index) and continual decrease in L* values (brightness index) was observed (Fig. 1B and C). The application of 80% oxygen pretreatment on whole potato tuber maintained the lowest a* values and the highest L* values throughout storage. For the overall color change, ΔE* of samples with 80% oxygen pretreatment for 20 min significantly decreased during the entire storage time. However, the 60% oxygen pretreatment hadn’t so more effect on ΔE* than 80% oxygen pretreatment. The higher a* values, which expressed the color of red index, the higher browning (Liu et al., 2019). In term of a* values, the 80% oxygen pretreatment expressed obviously anti-browning effect, which was consistent with the initial high O2 MAP treatment on fresh-cut eggplants (Li et al., 2014). Oddly, the 60% oxygen pretreatment was induced browning after 6 d storage, which may indicate that the induction effect of high oxygen requires a concentration threshold to trigger the plant oxygen sensing. 3.2. Malondialdehyde (MDA) content, membrane permeability and antioxidant capacity As an important indicator of the cell membrane and the product of cytomembrane peroxidization, MDA content is a common index of lipid peroxidation (Landi, 2017). The MDA content of fresh-cut potato slices increased continuously during the first 6 d storage (Fig. 2A). Obviously, the MDA accumulation of potato slices treated by high oxygen pretreatment were higher than control at the first 2 d storage time, which 3
Food Chemistry 301 (2019) 125287
X. Liu, et al.
Fig. 1. Effect of high oxygen pretreatment on the appearance and color change of fresh-cut potato slices. (A) Photograph, (B) a* value change, (C) L* value change, (D) ΔE value change of potato slices of air (Control) or high oxygen (60%, and 80%) 20 min pretreatment on the whole potato tubers during storage at 4 °C. The results are represented as means ± standard deviations. Different letters represent significant differences among different treatment for each sampling time at P ≤ 0.05.
phenols content, and reduce the oxygen contact (Kader & BenYehoshua, 2000; Liu et al., 2018). In this study, we found the fourth models that increase the antioxidant capacity and PAL activity, which early induced the signaling perception and transduction of stress resistance.
concentration pretreatment. Usually, the mechanism progresses including browning reaction exist the equilibrium feedback. The PAL will catalyze the first step of phenylpropanol biosynthesis, and then varies of phenolic compounds will be further produced (Bate et al., 1994). So, the activity of PAL decreasing tended to higher in 80% oxygen treatment, too. Meanwhile, higher phenolic compounds content would scavenge more free radicals, which may be the reason that why the POD activity and antioxidant capacity was higher in 80% oxygen pretreatment (Figs. 3B and 2C). Generally, there are three main kinds of anti-browning models, including inhibiting POD and PPO activity, retard the increase of the total
4. Conclusion In conclusion, we first reported and analyzed the effectively method of anti-browning on fresh-cut potato slices using short-time high oxygen pretreatments to the whole potato tuber at the optimal concentration
Fig. 2. Effects of high oxygen pretreatment on (A) MDA content, (B) membrane permeability and (C) antioxidant capacity of the fresh-cut potato slices by air (Control) or high oxygen (60%, and 80%) pre-treating during 4 °C storage. The results are represented as means ± standard deviations. Different letters represent significant differences among different treatment for each sampling time at P ≤ 0.05. 4
Food Chemistry 301 (2019) 125287
X. Liu, et al.
Fig. 3. Effects of high oxygen pretreatment on (A) PPO activity, (B) POD activity, (C) PAL activity and (D) total phenol content of fresh-cut potato slices of air (Control) or high oxygen (60%, and 80%) treated during storage at 4 °C for 8 d. Different letters represent significant differences among different treatment for each sampling time at P ≤ 0.05.
(80%). The results reflected that the 80% oxygen pretreatment could not only inhibiting the PPO activity, but also significantly enhancing the antioxidant capacity, though there were slightly increasing the activity of PAL, POD and the substrate generation of total phenol during storage time. Meanwhile, with the high oxygen pretreatment, the accumulation of MDA was significantly inhibited, and the cell integrity maintained better. As a whole, the short-time high oxygen pretreatment gives us a simple, safe, low cost and convenient method for antibrowning that will be helpful for fresh-cut potato processing.
atmospheric oxygen and modified atmosphere conditions. Postharvest Biology and Technology, 33(1), 51–59. Assis, J. S., Maldonado, R., Muñoz, T., Escribano, M. I., & Merodio, C. (2001). Effect of high carbon dioxide concentration on PAL activity and phenolic contents in ripening cherimoya fruit. Postharvest Biology and Technology, 23(1), 33–39. Azevedo, V. M., Dias, M. V., de Siqueira Elias, H. H., Fukushima, K. L., Silva, E. K., de Deus Souza Carneiro, J., ... Borges, S. V. (2018). Effect of whey protein isolate films incorporated with montmorillonite and citric acid on the preservation of fresh-cut apples. Food Research International (Ottawa, Ontario), 107, 306–313. Bate, N. J., Orr, J., Ni, W., Meromi, A., Nadler-Hassar, T., Doerner, P. W., et al. (1994). Quantitative relationship between phenylalanine ammonia-lyase levels and phenylpropanoid accumulation in transgenic tobacco identifies a rate-determining step in natural product synthesis. Proceedings of the National Academy of Sciences of the United States of America, 91, 608–7612. Calder, B. L., Skonberg, D. I., Davis-Dentici, K., Hughes, B. H., & Bolton, J. C. (2011). The effectiveness of ozone and acidulant treatments in extending the refrigerated shelf life of fresh-cut potatoes. Journal of Food Science, 76(8), S492–S498. Cantos, E., Tudela, J. A., Gil, M. I., & Espín, J. C. (2002). Phenolic compounds and related enzymes are not rate-limiting in browning development of fresh-cut potatoes. Journal of Agricultural and Food Chemistry, 50(10), 3015–3023. Dong, X., Wrolstad, R. E., & Sugar, D. (2000). Extending shelf life of fresh-cut pears. Journal of Food Science, 65(1), 181–186. Fu, Y., Zhang, K., Wang, N., & Du, J. (2007). Effects of aqueous chlorine dioxide treatment on polyphenol oxidases from Golden Delicious apple. LWT – Food Science and Technology, 40(8), 1362–1368. Gao, H., Chai, H., Cheng, N., & Cao, W. (2017). Effects of 24-epibrassinolide on enzymatic browning and antioxidant activity of fresh-cut lotus root slices. Food Chemistry, 217, 45–51. Geysen, S., Escalona, V. H., Verlinden, B. E., & Nicolai, B. M. (2007). Modelling the effect of super-atmospheric oxygen and carbon dioxide concentrations on the respiration of fresh-cut butterhead lettuce. Journal of the Science of Food and Agriculture, 87(2), 218–226. Goyeneche, R., Agueero, M. V., Roura, S., & Di Scala, K. (2014). Application of citric acid and mild heat shock to minimally processed sliced radish: Color evaluation. Postharvest Biology and Technology, 93, 106–113. Jacobo-Velazquez, D. A., Martinez-Hernandez, G. B., Rodriguez, S. D. C., Cao, C., & Cisneros-Zevallos, L. (2011). Plants as Biofactories: Physiological role of reactive oxygen species on the accumulation of phenolic antioxidants in carrot tissue under
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgments This work was supported by grants from the Natural Science Foundation of Tianjin, China (17JCZDJC34300) and Key Projects in the National Science and Technology Pillar Program during the Twelve Five-year Plan Period of China (2015BAD16B02). References Ali, H. M., El-Gizawy, A. M., El-Bassiouny, R. E. I., & Saleh, M. A. (2016). The role of various amino acids in enzymatic browning process in potato tubers, and identifying the browning products. Food Chemistry, 192, 879–885. Allende, A., Luo, Y. G., McEvoy, J. L., Artes, F., & Wang, C. Y. (2004). Microbial and quality changes in minimally processed baby spinach leaves stored under super
5
Food Chemistry 301 (2019) 125287
X. Liu, et al.
with conventional low-O2 active and passive modified atmosphere packaging. Journal of Agricultural and Food Chemistry, 56(3), 932–940. Paul, M. V., Iyer, S., Amerhauser, C., Lehmann, M., van Dongen, J. T., & Geigenberger, P. (2016). Oxygen sensing via the ethylene response transcription factor RAP2.12 affects plant metabolism and performance under both normoxia and hypoxia. Plant Physiology, 172(1), 141–153. Perez, A. G., & Sanz, C. (2001). Effect of high-oxygen and high-carbon-dioxide atmospheres on strawberry flavor and other quality traits. Journal of Agricultural and Food Chemistry, 49(5), 2370–2375. Shen, X., Zhang, M., Devahastin, S., & Guo, Z. (2019). Effects of pressurized argon and nitrogen treatments in combination with modified atmosphere on quality characteristics of fresh-cut potatoes. Postharvest Biology and Technology, 149, 159–165. Supapvanich, S., Mitrsang, P., Srinorkham, P., Boonyaritthongchai, P., & Wongs-Aree, C. (2016). Effects of fresh Aloe vera gel coating on browning alleviation of fresh cut wax apple (Syzygium samarangenese) fruit cv. Taaptimjaan. Journal of Food Science and Technology-Mysore, 53(6), 2844–2850. Van der Steen, C., Jacxsens, L., Devlieghere, F., & Debevere, J. (2002). Combining high oxygen atmospheres with low oxygen modified atmosphere packaging to improve the keeping quality of strawberries and raspberries. Postharvest Biology and Technology, 26(1), 49–58. Wang, D., Chen, L., Ma, Y., Zhang, M., Zhao, Y., & Zhao, X. (2019). Effect of UV-C treatment on the quality of fresh-cut lotus (Nelumbo nucifera Gaertn.) root. Food Chemistry, 278, 659–664. Wang, Q., Cao, Y., Zhou, L., Jiang, C., Feng, Y., & Wei, S. (2015). Effects of postharvest curing treatment on flesh colour and phenolic metabolism in fresh-cut potato products. Food Chemistry, 169, 246–254. Wills, R. B. H., & Li, Y. (2016). Use of arginine to inhibit browning on fresh cut apple and lettuce. Postharvest Biology and Technology, 113, 66–68. Wszelaki, A. L., & Mitcham, E. J. (2000). Effects of superatmospheric oxygen on strawberry fruit quality and decay. Postharvest Biology and Technology, 20(2), 125–133. Xu, W., Peng, X., Luo, Y., Wang, J., Guo, X., & Huang, K. (2009). Physiological and biochemical responses of grapefruit seed extract dip on ‘Redglobe’ grape. LWT – Food Science and Technology, 42(2), 471–476. You, Y., Jiang, Y., Sun, J., Liu, H., Song, L., & Duan, X. (2012). Effects of short-term anoxia treatment on browning of fresh-cut Chinese water chestnut in relation to antioxidant activity. Food Chemistry, 132(3), 1191–1196. Zheng, Y. H., Wang, C. Y., Wang, S. Y., & Zheng, W. (2003). Effect of high-oxygen atmospheres on blueberry phenolics, anthocyanins, and antioxidant capacity. Journal of Agricultural and Food Chemistry, 51(24), 7162–7169. Zheng, Y., Yang, Z., & Chen, X. (2008). Effect of high oxygen atmospheres on fruit decay and quality in Chinese bayberries, strawberries and blueberries. Food Control, 19(5), 470–474.
wounding and hyperoxia stress. Journal of Agricultural and Food Chemistry, 59(12), 6583–6593. Jeong, J., Nam, P., Lee, S., & Lee, K. (2011). Antioxidant activities of Korean rice wine concentrates. Journal of Agricultural and Food Chemistry, 59(13), 7039–7044. Kader, A. A., & Ben-Yehoshua, S. (2000). Effects of superatmospheric oxygen levels on postharvest physiology and quality of fresh fruits and vegetables. Postharvest Biology and Technology, 20(1), 1–13. Kim, D., Kim, H., Chung, H., & Moon, K. (2014). Browning control of fresh-cut lettuce by phytoncide treatment. Food Chemistry, 159, 188–192. Landi, M. (2017). Commentary to: “Improving the thiobarbituric acid-reactive-substances assay for estimating lipid peroxidation in plant tissues containing anthocyanin and other interfering compounds” by Hodges et al., Planta (1999) 207:604–611. Planta, 245(6), 1067. Li, W. L., Li, X. H., Fan, X., Tang, Y., & Yun, J. (2012). Response of antioxidant activity and sensory quality in fresh-cut pear as affected by high O2 active packaging in comparison with low O2 packaging. Food Science and Technology International, 18(3), 197–205. Li, X., Jiang, Y., Li, W., Tang, Y., & Yun, J. (2014). Effects of ascorbic acid and high oxygen modified atmosphere packaging during storage of fresh-cut eggplants. Food Science and Technology International, 20(2), 99–108. Liu, X., Lu, Y., Yang, Q., Yang, H., Li, Y., Li, T., et al. (2018). Cod peptides inhibit browning in fresh-cut potato slices: A potential anti-browning agent of random peptides for regulating food properties. Postharvest Biology and Technology, 146, 36–42. Liu, X., Yang, Q., Lu, Y., Li, Y., Li, T., Zhou, B., et al. (2019). Effect of purslane (Portulaca oleracea L.) extract on anti-browning of fresh-cut potato slices during storage. Food Chemistry, 283, 445–453. Ma, L., Zhang, M., Bhandari, B., & Gao, Z. (2017). Recent developments in novel shelf life extension technologies of fresh-cut fruits and vegetables. Trends in Food Science & Technology, 64, 23–38. Martinez, M. V., & Whitaker, J. R. (1995). The biochemistry and control of enzymatic browning, vol. 6, 195–200. McEvily, A. J., Iyengar, R., & Otwell, W. S. (1992). Inhibition of enzymatic browning in foods and beverages. Critical Reviews in Food Science and Nutrition, 32(3), 253–273. Mishra, B. B., Gautam, S., & Sharma, A. (2012). Browning of fresh-cut eggplant: Impact of cutting and storage. Postharvest Biology and Technology, 67, 44–51. Moon, K. M., Lee, B., Cho, W. K., Lee, B. S., Kim, C. Y., & Ma, J. Y. (2018). Swertiajaponin as an anti-browning and antioxidant flavonoid. Food Chemistry, 252, 207–214. Odriozola-Serrano, I., Oms-Oliu, G., Soliva-Fortuny, R., & Martín-Belloso, O. (2009). Effect of high-oxygen atmospheres on the antioxidant potential of fresh-cut tomatoes. Journal of Agricultural and Food Chemistry, 57(15), 6603–6610. Oms-Oliu, G., Odriozola-Serrano, I., Soliva-Fortuny, R., & Martin-Belloso, O. (2008). Antioxidant content of fresh-cut pears stored in high-O2 active packages compared
6
Contents lists available at ScienceDirect
Food Chemistry journal homepage: www.elsevier.com/locate/foodchem
Short communication
Effect of high oxygen pretreatment of whole tuber on anti-browning of freshcut potato slices during storage
T
⁎
Xia Liu , Ting Wang, Yuzhuo Lu, Qian Yang, Yuan Li, Xudong Deng, Ying Liu, Xinru Du, Liping Qiao, Jiaxuan Zheng State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Food Nutrition and Safety, Ministry of Education of China, College of Food Engineering and Biotechnology, Tianjin University of Science &Technology, Tianjin 300457, PR China
A R T I C LE I N FO
A B S T R A C T
Keywords: High oxygen pretreatment Enzymatic browning Fresh-cut potato
The surface browning usually occurs on fresh-cut potato during storage. The effect of short-time high oxygen pretreatment on anti-browning of fresh-cut potato slices was investigated. The whole potato tubers were firstly immersed in the oxygen concentration of 21%, 60% and 80% for 20 min. Then, the potatoes were peeled, cut and stored at 4 °C for 8 days. The results showed that the short-time 80% oxygen pretreatment possessed significantly anti-browning effect by retarding the increase of polyphenol oxidase (PPO) activity and the accumulation of malondialdehyde (MDA) content, maintaining the cell integrity. Meanwhile, the 80% oxygen treatment could increase the activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD), and the total phenolic content. Importantly, the 80% oxygen treatment could effectively improve the antioxidant capacity. Overall, all results suggest that the short-time high oxygen pretreatment holds great promise on anti-browning of fresh-cut potato.
1. Introduction Fresh-cut fruit and vegetable has shown a growing market prospect with the acceleration of people’s pace of life because of their convenience, healthfulness and freshness (Kim, Kim, Chung, & Moon, 2014). Potato (Solanum tuberosum L.) is the main product of fresh-cut fruit and vegetable industry (Ma, Zhang, Bhandari, & Gao, 2017). However, the surface browning usually occurs on fresh-cut potato during storage, which leads to the poor appearance, a lower consumer's purchase decision, and a shorter shelf-life (Liu et al., 2019). Hence, the prevention of surface browning has been a focus on the fresh cutting industry’s field in recent decades. It is well known that the surface browning is mainly brought by enzymatic browning, a reaction that the phenolic compounds produce quinones and then these quinones transform into pigments when oxygen is present (Cantos, Tudela, Gil, & Espín, 2002; Moon et al., 2018; Supapvanich, Mitrsang, Srinorkham, Boonyaritthongchai, & Wongs-Aree, 2016). Polyphenol oxidase (PPO) is the key enzyme in the melanogenesis pathway of enzymatic browning, which catalyzes not only the hydroxylation of monophenols to diphenols but also the oxidation of diphenols to quinones (Martinez & Whitaker, 1995).
Meanwhile, the peroxidase (POD) is another important oxidative enzyme by the formation of free radical species during browning (McEvily, Iyengar, & Otwell, 1992). As well as POD, phenylalanine ammonia-lyase (PAL), an important wound-induced enzyme, is also involved in enzymatic browning. PAL catalyzes the browning substances formation of phenolic components by the L-phenylalanine pathway (Assis, Maldonado, Muñoz, Escribano, & Merodio, 2001; Cantos et al., 2002). Therefore, the regulation of PPO, POD and PAL activities is an crucial target for many anti-browning strategies (Liu et al., 2018, 2019). In recent years, many methods of anti-browning and keeping quality of fresh-cut products have been reported, including fumigation treatment (ozone, chlorine dioxide, pressurized argon and nitrogen), preventing oxygen contact treatment (chitosan, plant protein isolate films, modified atmosphere packaging), antioxidant and related enzyme inhibitor treatment (citric acid, ascorbic acid, 24-epibrassinolide, amino acid, purslane extract, cod peptides and swertiajaponin), and some physical- based methods (UV-C, heating combining modified atmosphere packaging) (Azevedo et al., 2018; Calder, Skonberg, DavisDentici, Hughes, & Bolton, 2011; Gao, Chai, Cheng, & Cao, 2017; Goyeneche, Agueero, Roura, & Di Scala, 2014; Li, Jiang, Li, Tang, &
Abbreviations: PPO, polyphenol oxidase; POD, peroxidase; PAL, phenylalamine ammonia lyase; MDA, malondialdehyde ⁎ Correspondence author. E-mail address: [email protected] (X. Liu). https://doi.org/10.1016/j.foodchem.2019.125287 Received 22 May 2019; Received in revised form 28 July 2019; Accepted 28 July 2019 Available online 29 July 2019 0308-8146/ © 2019 Elsevier Ltd. All rights reserved.
Food Chemistry 301 (2019) 125287
X. Liu, et al.
& Li, 2016). Firstly, the mixture of ground fresh-cut potatoes slices (2.0 g) and 60% ethanol extract (5.0 mL) were centrifuged at 10,000×g for 10 min. Then the supernatant (0.25 mL), distilled water (5.0 mL), Na2CO3 solution (0.80 mL) and folin-phenol reagent (0.25 mL) were mixed well at volumetric flask (25 mL) and then react for 30 min in dark place. Finally, the absorbance value was measured at 760 nm. The total phenolic content was expressed as g kg−1 in fresh weight using gallic acid standard solution as blank control.
Yun, 2014; Liu et al., 2018, 2019; Moon et al., 2018; Shen, Zhang, Devahastin, & Guo, 2019; Wang et al., 2019). As a whole, most of them were chemical-based treatments that raised the safety concerns among consumers, or made the fresh-cut processing relatively complicated. High oxygen treatment has been used during preservation of fruits and vegetables, which promoted the increases of antioxidant capacity and total phenolic contents by the > 60% O2 concentration continuously treatment (Zheng, Wang, Wang, & Zheng, 2003). Continuous treatment of 60%–100% oxygen also could significantly inhibit fruit decay, the rates of respiration and ethylene production, and also inactivate pathogens activity (Allende, Luo, McEvoy, Artes, & Wang, 2004; Geysen, Escalona, Verlinden, & Nicolai, 2007; Kader & BenYehoshua, 2000; Wszelaki & Mitcham, 2000; Zheng, Yang, & Chen, 2008). The increase of antioxidant capacity, which was induced by superatmospheric oxygen may result from the Redox biological system and the integrity of the membrane (Oms-Oliu, Odriozola-Serrano, Soliva-Fortuny, & Martin-Belloso, 2008; Van der Steen, Jacxsens, Devlieghere, & Debevere, 2002). Moreover, as an abiotic stress, the high oxygen treatment inevitably regulates the reactive oxygen species (ROS) and Redox biological system (Li et al., 2014; Odriozola-Serrano, Oms-Oliu, Soliva-Fortuny, & Martín-Belloso, 2009; Perez & Sanz, 2001). However, there is little report on the effect of short-time high oxygen pretreatment for whole potato tuber on the browning of fresh-cut potato by initiating the resistance. In this research, the effect of short-time high oxygen pretreatment of whole tuber as a pre-stimulation on antibrowning were evaluated by investigating the activity of PPO, POD and PAL, total phenol content, membrane permeability, malondialdehyde content (MDA) and antioxidant capacity during fresh-cut potato slices storage at 4 °C.
2.4. Membrane permeability The relative electrical conductivity was measured according to existing test methods for expressing membrane permeability (Xu et al., 2009). Firstly, the uniform discs of 10 mm diameter was obtained from the samples by a hole puncher. Secondly, for removing the electrolytes adhering of the potato slices surface, deionized water was used to wash these discs for three times. Then after drying by filter paper, these discs with deionized water (20 mL) were boiled for 15 min. The relative electrical conductivity values were measured by a conductometer (DDS11A type, Shanghai, China). 2.5. MDA content The fresh potatoes (5.0 g), trichloroacetic acid (10.0 mL, 100 g L−1) were mixed and ground together with some quartz sand. After centrifuging at 10,000×g for 20 min, the supernatant (3.0 mL) and thiobarbituric acid solution (3.0 mL, 0.6%, w/w) was blend. Then, the mixture was boiled for 15 min. After cooling to room temperature, the mixture was centrifuged at 10,000×g for 15 min. Finally, the absorbance of the supernatant was measured at 450 nm, 532 nm and 600 nm. The expression of MDA content of fresh sample weight was µmol kg−1 (Dong, Wrolstad, & Sugar, 2000).
2. Materials and methods 2.1. Material and sample preparation
2.6. The activity of PPO The potatoes (S. tuberosum, cv Netherlands 7) were purchased from a farm market in Tianjin, China. The fresh potatoes with uniform size and no mechanical damage, pests and diseases were screened. Then, the selected potatoes were placed in a sealed jar, which connected with the gas control device for high oxygen pretreatment. Then, the original air in the jar was discharged by N2, and then filled with concentrations of 60% and 80% oxygen for 20 min, respectively. And a group of potatoes was immersed in air condition (oxygen concentration 21%) as blank control. The gas concentration was checked regularly with an O2/CO2 analyzer (PBI-Dansensor A/S, Danish, Ringsted, Denmark). The selected potatoes were cleaned, peeled and sliced to 0.5 cm thick slices. For removing starch, the potato slices were washed with water, dried with gauze and packed into the ziplock bags (polyethylene, PE) (Ali, El-Gizawy, El-Bassiouny, & Saleh, 2016). Finally, all the samples were stored at 4 ± 1 °C for 8 days. For each treatment, three replicates were analyzed and investigated in the next experiment for every two days.
The PPO activity was determined according to the previously reported method (Fu, Zhang, Wang, & Du, 2007). Firstly, fresh-cut potatoes slices (2 g) with acetic acid-sodium acetate buffer (5.0 mL, 0.1 mol L−1, pH 5.5) were ground. After centrifuging at 10,000×g for 30 min, supernatant (100 mL), acetic acid-sodium acetate buffer (4 mL, 0.05 mol L−1, pH 5.5) and catechol solution (1 mL, 0.05 mol L−1) were rapidly mixed and measured the absorbance value at 420 nm. The was expressed in of fresh weight. The expression of PPO activity of fresh sample weight was U g−1. 2.7. The activity of POD The activity of POD was assayed according to the reported method (Li, Li, Fan, Tang, & Yun, 2012). Firstly, the mixture of ground fresh potato slices (2 g) and acetic acid-sodium acetate buffer (5.0 mL, 0.1 mol L−1, pH 5.5) were centrifuged at 10,000×g for 30 min. Then, supernatant (5.0 mL) and guaiacol solution (5.0 mL, 0.025 mol L−1) were mixed and rapidly added H2O2 solution (0.2 mL, 0.5 mmol−1), then immediately measured the absorbance value at 470 nm. The expression of POD activity of fresh sample weight was U g−1.
2.2. Measurement of color The surface color was measured by a chromameter (CM-3600d, Konica Minolta, Japan), which provided lightness (L*), reddish–greenish (a*) and yellowish–bluish (b*) values (Wang et al., 2015). The comprehensive evaluation index of color difference (ΔE*) was compared with the initial time, which calculated according to the following formula: ΔE* .
2.8. The activity of PAL The activity of PAL was determined according to the reported method (Mishra, Gautam, & Sharma, 2012). Firstly, the mixture of ground fresh-cut potatoes slices (1 g) and boric acid buffer (5.0 mL, PH 8.8, 0.05 mol L−1) were centrifuged at 10,000×g for 30 min. Secondly, after boric acid buffer (3.0 mL, PH 8.8, 0.05 mol L−1) and L-phenylalanine (0.5 mL, 0.02 mol L−1) blending and incubating at 37 °C for 10 min, the supernatant (0.5 mL) was quickly added. Then, the initial absorbance value was measured at 470 nm. Finally, after the whole
2.3. Total phenolic content The content of total phenols was measured according to the FolinCiocalteu procedure with slight modification (Cantos et al., 2002; Wills 2
Food Chemistry 301 (2019) 125287
X. Liu, et al.
may be because high oxygen pretreatment induced the peroxidization reaction. However, after that, the MDA content of high oxygen pretreatment was significantly lower than control. In term of the overall changes of plasma membrane permeability, which was expressed by relative electrical conductivity, the greater membrane permeability, the greater membrane damage degree. From Fig. 2B, the relative electrical conductivity was lower than control not only for 60% high oxygen but also for 80% high oxygen samples after 2 d storage. In addition, the antioxidant capacity of fresh-cut potato slices was measured by α,αdiphenyl-β-picrylhydrazyl (DPPH) free radical scavenging rate (Fig. 2C). The highest rates of free radical scavenging rate were observed in 80% short-time oxygen pretreatment during the entire storage time at 4 °C. Overall, the 80% oxygen short-term pretreatment could significantly delay the damage of cell membrane, retard the accumulation of MDA, and induced the antioxidant capacity, which was consistent with the effects of short-term anoxia treatment on browning of fresh-cut Chinese water chestnut (You et al., 2012). As a kind of abiotic stress, the high oxygen pretreatment may provoke stress response not only causing the imbalance of physiological metabolic but also resulting in the production of reactive oxygen species (ROS) (Jacobo-Velazquez, Martinez-Hernandez, Rodriguez, Cao, & Cisneros-Zevallos, 2011). On the other hand, ROS mediated signal pathway and secondary messengers are activated, especially triggered serial redox reactions. Here, the samples of 80% and 60% oxygen short-time treatment had been induced systemic resistance (ISR) due to activate Redox system before wounding stress of peeling and cutting. Then, many domino effects of wounding stress would be early launch resulting anti-browning, which maybe the same mechanism of hypoxia by ISR (Paul et al., 2016).
mixture incubating at 37 °C for 60 min, the absorbance value at 470 nm was measured. The expression of PAL activity of fresh sample weight was U g−1. 2.9. Antioxidant capacity The antioxidant activity was expressed as the free radical scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (Jeong, Nam, Lee, & Lee, 2011). The fresh potato slices were ground and centrifuged at 10,000×g for 15 min at 4 °C. Then, the supernatant was taken for reserve. Firstly, 4.0 mL DPPH solution (257.7 mg L−1) and 1 mL ethanol (95%, w/w) were mixed and measured the absorbance value at 517 nm after 30 min reaction (A0). Then, 1 mL supernatant and 4 mL ethanol (95%, w/w) were mixed and measured the absorbance value at 517 nm after 30 min reaction (Ar). Finally, 1 mL supernatant, 4 mL DPPH solution (257.7 mg L−1) were mixed and obtained the absorbance value at 517 nm after 30 min reaction (As). The final DPPH values were calculated by the following formula: DPPH % = {1 − (As − Ar)/A0} × 100. 2.10. Statistical analysis All treatment samples were carried out in triplicate. One-way analysis of variance (ANOVA) was used to analyze the experimental data by SPSS13.0. Data expressed as mean ± SD, and P ≤ 0.05 was considered to be significant by LSD test. 3. Results and discussion 3.1. Effect of high oxygen pretreatment to whole tuber on surface color and overall visual quality
3.3. The activity of PPO, POD and PAL and total phenolic content The browning reaction of fresh-cut fruit and vegetable is very complex. The substrate levels, cell damage degree, enzyme activity and so on all could affect the reaction process of browning in fresh-cut fruit and vegetable (Wang et al., 2019). The enzyme activity change of PPO, POD and PAL, and the total phenolic content change were shown in Fig. 3 during fresh-cut potato slices storage. Interestingly, the inductive effect of high oxygen pretreatment for the whole potato on the activity of PPO and POD, browning reaction-related enzymes were inconsistent (Fig. 3A and B). Fig. 3A showed an overall increasing trend for the activity of PPO with the storage time. Except for the first two days, the activity of PPO were significantly inhibited by short-time high oxygen pretreatment. And, the treatment with 80% oxygen pretreatment possessed the lowest activity after 4 d storage. Different from PPO, the activity of POD with high oxygen pretreated expressed higher catalysis activity than control during the whole storage period. Oddly, the activity of PAL, the primary enzyme involving in the browning substrate synthesis (phenolic compounds), was conflicted between 60% and 80% high oxygen pretreatment (Fig. 3C). The upregulated activity of PAL, but down-regulated activity was significantly come out in samples with 80% high oxygen pretreatment and 60% high oxygen pretreatment, respectively. The results were consistent with the reported results of continuously superatmospheric oxygen treatment (Geysen et al., 2007; Kader & Ben-Yehoshua, 2000; Zheng et al., 2003, 2008). As well as the PAL activity, the total phenolic content of potato slices with 80% oxygen treated was significantly higher than control, but the phenolic content with 60% oxygen treatment was lower than control at the first 4 d storage (Fig. 3D). Meanwhile, after 4 d storage, the total phenolic content tended to be similar in different groups but an increase in samples with 80% oxygen treated at 8 d storage. Together, the activities of PAL were increased at first 4 d because of the initiation of inducible resistance, but decreased after 4 d storage maybe because of the enough total phenolic content accumulation. Here, the results showed that the related enzyme activities, including PPO, POD and PAL, could be regulated by moderate oxygen
The effect of high oxygen pretreatment to whole tuber on the surface color and overall visual quality was investigated (Fig. 1). From the Fig. 1A, the effect of anti-browning was the most obvious on the overall visual quality in samples with 80% oxygen pretreatment, but the slight anti-browning effect of 60% oxygen pretreatment than the control group during the entire 8 days storage at 4 °C. In particular, the 80% oxygen pretreatment significantly maintained the yellow color, it was similar to the initial color even after 6 d storage (Fig. 1A). Like the overall visual quality, the continual increase in the a* values (red index) and continual decrease in L* values (brightness index) was observed (Fig. 1B and C). The application of 80% oxygen pretreatment on whole potato tuber maintained the lowest a* values and the highest L* values throughout storage. For the overall color change, ΔE* of samples with 80% oxygen pretreatment for 20 min significantly decreased during the entire storage time. However, the 60% oxygen pretreatment hadn’t so more effect on ΔE* than 80% oxygen pretreatment. The higher a* values, which expressed the color of red index, the higher browning (Liu et al., 2019). In term of a* values, the 80% oxygen pretreatment expressed obviously anti-browning effect, which was consistent with the initial high O2 MAP treatment on fresh-cut eggplants (Li et al., 2014). Oddly, the 60% oxygen pretreatment was induced browning after 6 d storage, which may indicate that the induction effect of high oxygen requires a concentration threshold to trigger the plant oxygen sensing. 3.2. Malondialdehyde (MDA) content, membrane permeability and antioxidant capacity As an important indicator of the cell membrane and the product of cytomembrane peroxidization, MDA content is a common index of lipid peroxidation (Landi, 2017). The MDA content of fresh-cut potato slices increased continuously during the first 6 d storage (Fig. 2A). Obviously, the MDA accumulation of potato slices treated by high oxygen pretreatment were higher than control at the first 2 d storage time, which 3
Food Chemistry 301 (2019) 125287
X. Liu, et al.
Fig. 1. Effect of high oxygen pretreatment on the appearance and color change of fresh-cut potato slices. (A) Photograph, (B) a* value change, (C) L* value change, (D) ΔE value change of potato slices of air (Control) or high oxygen (60%, and 80%) 20 min pretreatment on the whole potato tubers during storage at 4 °C. The results are represented as means ± standard deviations. Different letters represent significant differences among different treatment for each sampling time at P ≤ 0.05.
phenols content, and reduce the oxygen contact (Kader & BenYehoshua, 2000; Liu et al., 2018). In this study, we found the fourth models that increase the antioxidant capacity and PAL activity, which early induced the signaling perception and transduction of stress resistance.
concentration pretreatment. Usually, the mechanism progresses including browning reaction exist the equilibrium feedback. The PAL will catalyze the first step of phenylpropanol biosynthesis, and then varies of phenolic compounds will be further produced (Bate et al., 1994). So, the activity of PAL decreasing tended to higher in 80% oxygen treatment, too. Meanwhile, higher phenolic compounds content would scavenge more free radicals, which may be the reason that why the POD activity and antioxidant capacity was higher in 80% oxygen pretreatment (Figs. 3B and 2C). Generally, there are three main kinds of anti-browning models, including inhibiting POD and PPO activity, retard the increase of the total
4. Conclusion In conclusion, we first reported and analyzed the effectively method of anti-browning on fresh-cut potato slices using short-time high oxygen pretreatments to the whole potato tuber at the optimal concentration
Fig. 2. Effects of high oxygen pretreatment on (A) MDA content, (B) membrane permeability and (C) antioxidant capacity of the fresh-cut potato slices by air (Control) or high oxygen (60%, and 80%) pre-treating during 4 °C storage. The results are represented as means ± standard deviations. Different letters represent significant differences among different treatment for each sampling time at P ≤ 0.05. 4
Food Chemistry 301 (2019) 125287
X. Liu, et al.
Fig. 3. Effects of high oxygen pretreatment on (A) PPO activity, (B) POD activity, (C) PAL activity and (D) total phenol content of fresh-cut potato slices of air (Control) or high oxygen (60%, and 80%) treated during storage at 4 °C for 8 d. Different letters represent significant differences among different treatment for each sampling time at P ≤ 0.05.
(80%). The results reflected that the 80% oxygen pretreatment could not only inhibiting the PPO activity, but also significantly enhancing the antioxidant capacity, though there were slightly increasing the activity of PAL, POD and the substrate generation of total phenol during storage time. Meanwhile, with the high oxygen pretreatment, the accumulation of MDA was significantly inhibited, and the cell integrity maintained better. As a whole, the short-time high oxygen pretreatment gives us a simple, safe, low cost and convenient method for antibrowning that will be helpful for fresh-cut potato processing.
atmospheric oxygen and modified atmosphere conditions. Postharvest Biology and Technology, 33(1), 51–59. Assis, J. S., Maldonado, R., Muñoz, T., Escribano, M. I., & Merodio, C. (2001). Effect of high carbon dioxide concentration on PAL activity and phenolic contents in ripening cherimoya fruit. Postharvest Biology and Technology, 23(1), 33–39. Azevedo, V. M., Dias, M. V., de Siqueira Elias, H. H., Fukushima, K. L., Silva, E. K., de Deus Souza Carneiro, J., ... Borges, S. V. (2018). Effect of whey protein isolate films incorporated with montmorillonite and citric acid on the preservation of fresh-cut apples. Food Research International (Ottawa, Ontario), 107, 306–313. Bate, N. J., Orr, J., Ni, W., Meromi, A., Nadler-Hassar, T., Doerner, P. W., et al. (1994). Quantitative relationship between phenylalanine ammonia-lyase levels and phenylpropanoid accumulation in transgenic tobacco identifies a rate-determining step in natural product synthesis. Proceedings of the National Academy of Sciences of the United States of America, 91, 608–7612. Calder, B. L., Skonberg, D. I., Davis-Dentici, K., Hughes, B. H., & Bolton, J. C. (2011). The effectiveness of ozone and acidulant treatments in extending the refrigerated shelf life of fresh-cut potatoes. Journal of Food Science, 76(8), S492–S498. Cantos, E., Tudela, J. A., Gil, M. I., & Espín, J. C. (2002). Phenolic compounds and related enzymes are not rate-limiting in browning development of fresh-cut potatoes. Journal of Agricultural and Food Chemistry, 50(10), 3015–3023. Dong, X., Wrolstad, R. E., & Sugar, D. (2000). Extending shelf life of fresh-cut pears. Journal of Food Science, 65(1), 181–186. Fu, Y., Zhang, K., Wang, N., & Du, J. (2007). Effects of aqueous chlorine dioxide treatment on polyphenol oxidases from Golden Delicious apple. LWT – Food Science and Technology, 40(8), 1362–1368. Gao, H., Chai, H., Cheng, N., & Cao, W. (2017). Effects of 24-epibrassinolide on enzymatic browning and antioxidant activity of fresh-cut lotus root slices. Food Chemistry, 217, 45–51. Geysen, S., Escalona, V. H., Verlinden, B. E., & Nicolai, B. M. (2007). Modelling the effect of super-atmospheric oxygen and carbon dioxide concentrations on the respiration of fresh-cut butterhead lettuce. Journal of the Science of Food and Agriculture, 87(2), 218–226. Goyeneche, R., Agueero, M. V., Roura, S., & Di Scala, K. (2014). Application of citric acid and mild heat shock to minimally processed sliced radish: Color evaluation. Postharvest Biology and Technology, 93, 106–113. Jacobo-Velazquez, D. A., Martinez-Hernandez, G. B., Rodriguez, S. D. C., Cao, C., & Cisneros-Zevallos, L. (2011). Plants as Biofactories: Physiological role of reactive oxygen species on the accumulation of phenolic antioxidants in carrot tissue under
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgments This work was supported by grants from the Natural Science Foundation of Tianjin, China (17JCZDJC34300) and Key Projects in the National Science and Technology Pillar Program during the Twelve Five-year Plan Period of China (2015BAD16B02). References Ali, H. M., El-Gizawy, A. M., El-Bassiouny, R. E. I., & Saleh, M. A. (2016). The role of various amino acids in enzymatic browning process in potato tubers, and identifying the browning products. Food Chemistry, 192, 879–885. Allende, A., Luo, Y. G., McEvoy, J. L., Artes, F., & Wang, C. Y. (2004). Microbial and quality changes in minimally processed baby spinach leaves stored under super
5
Food Chemistry 301 (2019) 125287
X. Liu, et al.
with conventional low-O2 active and passive modified atmosphere packaging. Journal of Agricultural and Food Chemistry, 56(3), 932–940. Paul, M. V., Iyer, S., Amerhauser, C., Lehmann, M., van Dongen, J. T., & Geigenberger, P. (2016). Oxygen sensing via the ethylene response transcription factor RAP2.12 affects plant metabolism and performance under both normoxia and hypoxia. Plant Physiology, 172(1), 141–153. Perez, A. G., & Sanz, C. (2001). Effect of high-oxygen and high-carbon-dioxide atmospheres on strawberry flavor and other quality traits. Journal of Agricultural and Food Chemistry, 49(5), 2370–2375. Shen, X., Zhang, M., Devahastin, S., & Guo, Z. (2019). Effects of pressurized argon and nitrogen treatments in combination with modified atmosphere on quality characteristics of fresh-cut potatoes. Postharvest Biology and Technology, 149, 159–165. Supapvanich, S., Mitrsang, P., Srinorkham, P., Boonyaritthongchai, P., & Wongs-Aree, C. (2016). Effects of fresh Aloe vera gel coating on browning alleviation of fresh cut wax apple (Syzygium samarangenese) fruit cv. Taaptimjaan. Journal of Food Science and Technology-Mysore, 53(6), 2844–2850. Van der Steen, C., Jacxsens, L., Devlieghere, F., & Debevere, J. (2002). Combining high oxygen atmospheres with low oxygen modified atmosphere packaging to improve the keeping quality of strawberries and raspberries. Postharvest Biology and Technology, 26(1), 49–58. Wang, D., Chen, L., Ma, Y., Zhang, M., Zhao, Y., & Zhao, X. (2019). Effect of UV-C treatment on the quality of fresh-cut lotus (Nelumbo nucifera Gaertn.) root. Food Chemistry, 278, 659–664. Wang, Q., Cao, Y., Zhou, L., Jiang, C., Feng, Y., & Wei, S. (2015). Effects of postharvest curing treatment on flesh colour and phenolic metabolism in fresh-cut potato products. Food Chemistry, 169, 246–254. Wills, R. B. H., & Li, Y. (2016). Use of arginine to inhibit browning on fresh cut apple and lettuce. Postharvest Biology and Technology, 113, 66–68. Wszelaki, A. L., & Mitcham, E. J. (2000). Effects of superatmospheric oxygen on strawberry fruit quality and decay. Postharvest Biology and Technology, 20(2), 125–133. Xu, W., Peng, X., Luo, Y., Wang, J., Guo, X., & Huang, K. (2009). Physiological and biochemical responses of grapefruit seed extract dip on ‘Redglobe’ grape. LWT – Food Science and Technology, 42(2), 471–476. You, Y., Jiang, Y., Sun, J., Liu, H., Song, L., & Duan, X. (2012). Effects of short-term anoxia treatment on browning of fresh-cut Chinese water chestnut in relation to antioxidant activity. Food Chemistry, 132(3), 1191–1196. Zheng, Y. H., Wang, C. Y., Wang, S. Y., & Zheng, W. (2003). Effect of high-oxygen atmospheres on blueberry phenolics, anthocyanins, and antioxidant capacity. Journal of Agricultural and Food Chemistry, 51(24), 7162–7169. Zheng, Y., Yang, Z., & Chen, X. (2008). Effect of high oxygen atmospheres on fruit decay and quality in Chinese bayberries, strawberries and blueberries. Food Control, 19(5), 470–474.
wounding and hyperoxia stress. Journal of Agricultural and Food Chemistry, 59(12), 6583–6593. Jeong, J., Nam, P., Lee, S., & Lee, K. (2011). Antioxidant activities of Korean rice wine concentrates. Journal of Agricultural and Food Chemistry, 59(13), 7039–7044. Kader, A. A., & Ben-Yehoshua, S. (2000). Effects of superatmospheric oxygen levels on postharvest physiology and quality of fresh fruits and vegetables. Postharvest Biology and Technology, 20(1), 1–13. Kim, D., Kim, H., Chung, H., & Moon, K. (2014). Browning control of fresh-cut lettuce by phytoncide treatment. Food Chemistry, 159, 188–192. Landi, M. (2017). Commentary to: “Improving the thiobarbituric acid-reactive-substances assay for estimating lipid peroxidation in plant tissues containing anthocyanin and other interfering compounds” by Hodges et al., Planta (1999) 207:604–611. Planta, 245(6), 1067. Li, W. L., Li, X. H., Fan, X., Tang, Y., & Yun, J. (2012). Response of antioxidant activity and sensory quality in fresh-cut pear as affected by high O2 active packaging in comparison with low O2 packaging. Food Science and Technology International, 18(3), 197–205. Li, X., Jiang, Y., Li, W., Tang, Y., & Yun, J. (2014). Effects of ascorbic acid and high oxygen modified atmosphere packaging during storage of fresh-cut eggplants. Food Science and Technology International, 20(2), 99–108. Liu, X., Lu, Y., Yang, Q., Yang, H., Li, Y., Li, T., et al. (2018). Cod peptides inhibit browning in fresh-cut potato slices: A potential anti-browning agent of random peptides for regulating food properties. Postharvest Biology and Technology, 146, 36–42. Liu, X., Yang, Q., Lu, Y., Li, Y., Li, T., Zhou, B., et al. (2019). Effect of purslane (Portulaca oleracea L.) extract on anti-browning of fresh-cut potato slices during storage. Food Chemistry, 283, 445–453. Ma, L., Zhang, M., Bhandari, B., & Gao, Z. (2017). Recent developments in novel shelf life extension technologies of fresh-cut fruits and vegetables. Trends in Food Science & Technology, 64, 23–38. Martinez, M. V., & Whitaker, J. R. (1995). The biochemistry and control of enzymatic browning, vol. 6, 195–200. McEvily, A. J., Iyengar, R., & Otwell, W. S. (1992). Inhibition of enzymatic browning in foods and beverages. Critical Reviews in Food Science and Nutrition, 32(3), 253–273. Mishra, B. B., Gautam, S., & Sharma, A. (2012). Browning of fresh-cut eggplant: Impact of cutting and storage. Postharvest Biology and Technology, 67, 44–51. Moon, K. M., Lee, B., Cho, W. K., Lee, B. S., Kim, C. Y., & Ma, J. Y. (2018). Swertiajaponin as an anti-browning and antioxidant flavonoid. Food Chemistry, 252, 207–214. Odriozola-Serrano, I., Oms-Oliu, G., Soliva-Fortuny, R., & Martín-Belloso, O. (2009). Effect of high-oxygen atmospheres on the antioxidant potential of fresh-cut tomatoes. Journal of Agricultural and Food Chemistry, 57(15), 6603–6610. Oms-Oliu, G., Odriozola-Serrano, I., Soliva-Fortuny, R., & Martin-Belloso, O. (2008). Antioxidant content of fresh-cut pears stored in high-O2 active packages compared
6