Cold Sterilization of Coconut Water Using Membrane Filtration: Effect of Membrane Property and Operating Condition

Abstract

Coconut water has been considered as a nutritional, refreshing and highly isotonic beverage with delicate aroma and flavor. In food sterilization technique, thermal processing, however tends to reduce these beneficial properties especially estrogen hormone and flavor. To overcome this limitation, this study therefore aimed to clarified and sterilized coconut water using non–thermal processing, membrane filtration. Hollow fiber microfiltration (MF) membrane with pore size of 0.1 and 0.2 μm and ultrafiltration (UF) membrane with molecular weight cut–off (MWCO) of 100 and 30 kDa were used. The effect of membrane pore size and MWCO on quality of clarified juice, permeate flux and fouling were studied. It was found that fresh coconut water and clarified coconut water obtained from MF and UF did not show difference in pH, total soluble solid, reducing sugar, estrogen hormone and minerals including calcium, magnesium, phosphorus, potassium and sodium. The results from microbiological analysis of the clarified coconut water showed that sterilized of coconut water was obtained using either MF or UF membranes. This microbiological quality of clarified coconut water was met the Thai legislation for juice and drinks. The permeate flux of MF was much higher than those of UF while the fouling resistance of UF membrane was much higher than those of MF membrane. The permeate flux of membrane with pore size of 0.1 £gm was slightly lower than that of membrane with pore size of 0.2 μm. The results also indicated that the major fouling of both MF and UF membranes was reversible. The irreversible fouling resistance of 0.1 μm membrane was the lowest and most of this irreversible fouling was external irreversible fouling, formed on the membrane surface. According to these results, it could be concluded that 0.1 μm membrane was the most suitable membrane for clarification and sterilization of coconut water. In addition, the effects of TMP, cross flow velocity (CFV) and the % recovery on permeate flux in batch concentration mode were also studied. It was found that the permeate flux of 0.1 μm membrane was significantly increased with increasing CFV and decreased as % recovery increased. These results suggested that permeate flux during MF of coconut water was dependent on reversible fouling and could be improved by using hydrodynamic modification techniques.

Development of a UV coupled indigenous hydrophilized polyamide membrane system for enhanced shelf life of mature coconut water

“…Many researchers have been using membrane filtration to concentrate natural juices (Girard and Fukumoto, 2000) such as apple (Youn et al, 2004), pear (Hernandez et al, 2009), pineapple, wine (Youravong et al, 2005), pomegranate (Solmaz et al, 2020), mosambi (Rai et al, 2008), citrus fruit, carrot (Cassano et al, 2003), coconut water (Laorko et al, 2008; Chowdhury et al, 2009), tender coconut water (Jayanti et al, 2010) and coconut milk (Fatimah et al, 2017). Chowdhury et al successfully designed a membrane filtration process to improve coconut water's shelf life at low temperatures for a long time without any deterioration (Chowdhury et al, 2005; Pristijono et al, 2018; Jianxin et al, 2020).…”

Economic Assessment for Cold Sterilization and Clarification of Pineapple Juice and Coconut Water using Microfiltration

“…The advantages of microfiltration in relation to the thermal process are the use of mild temperature. The process and techniques developed therefore can be employed for production of non-thermally or cold sterilized fruit juice which potentially maintain the nutritional quality, phytochemical property and sensorial attributes of the products, so call "freshlike products" [2][3][4][5]. However, with the exception of non-thermally sterilization, membrane has not been wildly used within fruit juice industry.…”

“…In addition, the performance of membrane process is dependent on membrane fouling and concentration polarization limiting the applications. Thus the techniques for improvement membrane process performance by reducing fouling and concentration polarization are always of interest including critical flux, back pulsing, gas sparging [7][8][9][10]. Among them gas spraging is a promising method able to significantly enhance the permeate flux of various feed solutions [8][9][10].…”

“…Thus the techniques for improvement membrane process performance by reducing fouling and concentration polarization are always of interest including critical flux, back pulsing, gas sparging [7][8][9][10]. Among them gas spraging is a promising method able to significantly enhance the permeate flux of various feed solutions [8][9][10]. Our previous studies also indicated that the permeate flux during microfiltration of pineapple juice and coconut water were varied, depending on operating conditions such as cross flow velocity (CFV) and gas sparging [4,5].…”

“…Among them gas spraging is a promising method able to significantly enhance the permeate flux of various feed solutions [8][9][10]. Our previous studies also indicated that the permeate flux during microfiltration of pineapple juice and coconut water were varied, depending on operating conditions such as cross flow velocity (CFV) and gas sparging [4,5]. It is known that permeate flux and fouling are key parameters in determination of MF-plant design influencing capital cost and operating cost [11].…”