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Storage quality of pineapple juice non thermally pasteurized and clarified by microfiltration Journal of Food Engineering 116 (2013) 554–561 Contents lists available at SciVerse ScienceDirect Journal[.]
Journal of Food Engineering 116 (2013) 554–561 Contents lists available at SciVerse ScienceDirect Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng Storage quality of pineapple juice non-thermally pasteurized and clarified by microfiltration Aporn Laorko a,b,c, Sasitorn Tongchitpakdee d, Wirote Youravong a,b,⇑ a Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai 90112, Thailand Membrane Science and Technology Research Center, Prince of Songkla University, Hat Yai 90112, Thailand c LPE’s Membrane Knowledge Center, Liquid Purification Engineering International Co., Ltd., Nonthaburi 11140, Thailand d Department of Food Science and Technology, Faculty of Agro-Industry, Kasetsart University, Bangkok 10900, Thailand b a r t i c l e i n f o Article history: Received September 2012 Received in revised form December 2012 Accepted 21 December 2012 Available online 28 December 2012 Keywords: Microfiltration Non-thermal processing Pineapple juice Phytochemical property Shelf-life a b s t r a c t Microfiltration (MF) is classified as a non-thermal process for the fruit juice industry It could provide a better preservation of the phytochemical property and flavor of the juice This work aimed to study the stability of phytochemical properties including vitamin C, total phenolic content, antioxidant capacity (2Diphenly-1-picrylhydrazyl: DPPH, free radical scavenging capacity and Oxygen Radical Absorbance Capacity: ORAC assays), microbial and chemical–physical (color, browning index, pH and total soluble solid) properties of MF-clarified pineapple juice during storage at various temperatures (i.e 4, 27, and 37 °C) The juices were clarified by microfiltration using hollow fiber module The results showed that most of the phytochemical properties and soluble components were retained in the juice after microfiltration No microbial growth was detected after months of storage The storage time and temperature did not affect total soluble solids and pH (P > 0.05) The color (L) of clarified juice stored at °C was lighter than the juices stored at higher temperature levels (P < 0.05) The phytochemical properties and total phenol content of the juice significantly decreased as storage time and temperature increased (P < 0.05) Vitamin C content was the attribute that affected storage time and temperature most as indicated by reaction rate constant and activated energy Storage of non-thermally pasteurized and clarified pineapple juice at °C was the most suitable since it allowed the best quality preservation Ó 2012 Elsevier Ltd All rights reserved Introduction Pineapple juice is very popular and, thus, highly consumed in many countries Thailand has been a world export leader of both concentrate and single strength pineapple juices for decades Its popularity is based on attractive aroma and flavor characteristics, and beneficial components that play a primary role in avoiding the risk of chronic diseases Pineapple juice is one of the fruits that contain high contents of antioxidant and phenolic compounds The phenolic compounds in pineapple juice are sinapyl-L-cysteine, N-cL-glutamyl-S-sinapyl-L-cysteine, S-sinapyl glutathione, and p-coumaric like compounds (Wen and Wrolstad, 2002) Pineapple juice also contains phytosterols such as ergostanol and stigmastanol (Ng and Hupé, 1999) These phytosterols have cholesterol-lowering effect by reducing absorption of cholesterol Vitamin C, a water soluble vitamin, plays an important role in antioxidant activity It reduces the risk of heart disease by preventing the oxidation of ⇑ Corresponding author at: Department of Food Technology, Faculty of AgroIndustry, Prince of Songkla University, Hat Yai 90112, Thailand Tel.: +66 7428 6321; fax: +66 7421 2889 E-mail address: wirote.y@psu.ac.th (W Youravong) 0260-8774/$ - see front matter Ó 2012 Elsevier Ltd All rights reserved http://dx.doi.org/10.1016/j.jfoodeng.2012.12.033 low-density lipoprotein (LDL) cholesterol It is well known that the conventional thermal treatments of fruit juice, including pasteurization and sterilization, ensure safety and extend shelf-life of the product However, these processes often cause detrimental change of the product quality because of severe heat treatment Membrane technology is an alternative method that reduces heat-associated the loss of nutritional and functional quality (e.g phytochemical properties) and has been successfully applied and introduced for commercial production of liquid foods such as juices (Carneiro et al., 2002; Cassano et al., 2007a, 2008; De Oliveira et al., 2012; Habibi et al., 2011; Jaeger de Carvalho et al., 2008; Kozak et al., 2008), wine (El Rayess et al., 2011; Ulbricht et al., 2009; Vernhet and Moutounet, 2002), and milk (RodríguezGonzález et al., 2011; Tan et al., 2010; Walkling-Ribeiro et al., 2011) In addition, membrane filtration processes could potentially be combined for clarification and preservation in single step Microfiltration (MF) could provide high quality, natural fresh taste and additive free products It is also simple, easy to scale up and characterized as low energy consumption process (Cassano et al., 2007a) Moreover, it has been reported that the use of MF for fruit juice processing permitted a good level of recovery of vitamin C and antioxidant capacity (Cassano et al., 2007b) During storage, 555 A Laorko et al / Journal of Food Engineering 116 (2013) 554–561 fruit juice is subjected to deterioration reactions such as microbial spoilage, phytochemical properties’ degradation and changes in color, texture and appearance (Cortés et al., 2008) Understanding the stability of product characteristics during storage may help producers in identifying not only suitable storage conditions but also the most significant characteristics that limit shelf-life Zheng and Lu (2011) evaluated stability of ascorbic acid, total phenols and DPPH radical scavenging activity of pasteurized pineapple juices The degradation rate of ascorbic acid, total phenols and DPPH radical scavenging activity were storage time and temperature dependent The half-life of ascorbic acid, and DPPH radical scavenging activity of pasteurized pineapple juice storage at 25 °C were approximately 25 h The MF process has been successfully employed for clarification and preservation of pineapple juice (Carneiro et al., 2002; Laorko et al., 2010, 2011) However, to date there is no research available on the stability of phytochemical properties during storage of MFclarified pineapple juices Therefore, the aim of this study was to investigate the stability of physical and phytochemical properties of MF-clarified pineapple juice during months of storage at 4, 27, and 37 °C The outcome was then used for determination of pineapple juice shelf-life and the most suitable storage condition that retains appreciated quality was recommended Materials and methods 2.1 Preparation of pineapple juice Fresh pineapples (Ananus Comosus L Merr.) were rinsed with tap water After peeling, fresh pineapples were cut into cm3 pieces and juice was extracted by mean of a hydraulic press Total soluble solids (TSSs) and pH values of the juice were in the range of 12.2–14.2 °Brix and 3.5–4.0, respectively The fresh pineapple juice was kept at °C before processing The pineapple juice was treated by 0.03% (v/v) of commercial pectinase (PectinexÒ ultra SP-L) at 25 ± °C for 60 before passing them through the membrane system (Carneiro et al., 2002) 2.2 Microfiltration The membrane was a autoclaveable polysulfone hollow fiber (Amersham Biosciences, UK) with a fiber diameter and length of mm and 30 cm, respectively The effective membrane area was 0.011 m2 The pore size of the membranes were 0.2 lm The membrane system consisted of a L stainless steel jacket-feed tank, variable-feed pump (Leeson, USA) and transducers (MBS 3000, Danfoss, Denmark) for pressure of the feed, retentate and permeate measurements The temperature of the feed was controlled by circulating chilled water through a jacket-feed tank The cross-flow velocity (CFV) and transmembrane pressure (TMP) were controlled using needle permeate valve, back pressure (retentate) valve and variable speed-feed pump The digital balance (GF-3000, A&D, Japan), connected to the computer, was used to measure the permeate flux The experiments were carried out in batch concentration mode (the retentate return to the feed tank) at constant CFV of 1.2 m/s, temperature of 20 ± °C and TMP of 1.0 bar The permeate sample was directly filled into sterilized glass bottles under aseptic conditions inside a laminar flow cabinet The bottles were sterilized in a hot air oven at 180 °C for h The laminar flow cabinet was sprayed with 70% alcohol and exposed overnight to germicidal ultraviolet light (UV-C, 254 nm with the intensity of 76 lm/cm2) A HEPA air filter system with 0.3 lm pore size and a 0.1375 m2 filtration area was installed to provide positive pressure and bacteria free air in the laminar flow cabinet 2.3 Storage conditions The clarified juice samples obtained from MF processing were stored at 4, 27 and 37 °C They were analyzed in triplicate at 0, 1, 2, 3, 4, and months of storage time 2.4 Pineapple juice analyses The color of samples was measured by a colorimeter (Colour Quest XT, Hunter lab, USA) It is classified by CIE (Comission Internationale l’Eclairage) into three dimension; L (brightness), a (red to green color) and b (yellow to blue color) The determination of the total color difference (DE) was carried out using the following equation; 2 DE ¼ DL2 ỵ Da2 ỵ Db ị1=2 1ị DE indicates the magnitude of the color difference between MFclarified juice before and after storage (Cortés et al., 2008) Chroma was determined using the following equation: 2 Chroma ẳ a2 ỵ b ị1=2 ð2Þ Non-enzymatic browning index was determined at an absorbance level of 420 nm with spectrophotometer (Thermo Spectronic, 4001/4, USA), according to the method of Meydav et al (1997) The pH values were measured using a pH meter (PB-20, Sartorius, Germany) The total soluble solids were measured by hand refractometer (ATAGO, Japan) The microbiological analyses of clarified juices including total plate, yeast and mold, and coliform counts of enzymatic pretreated pineapple juice were performed by the method.described in bacteriological analytical manual (BAM, 2002) Total vitamin C (L-ascorbic acid and dehydroascorbic acid) content was determined by high performance liquid chromatography (HPLC) The method was based on Zapata and Dufour (1992) with some modifications The juice sample (10 mL) was homogenized with 10 mL of extraction solution (0.1 M citric acid, 0.05% ethyldiaminetretraacetic acid (EDTA) in 5% aqueous methanol) for An internal standard of isoascorbic acid was added at 20 mg/100 g of fruit juice The homogenate was then centrifuged for 10 at 10,000g and °C After calibrating the pH with cold buffer, the pH of the supernatant was adjusted to 2.35–2.40 with N HCl The sample was passed through a sep-pack C 18 cartridge (Verti-pack) which had been preconditioned with 10 mL HPLC grade methanol followed by 10 mL of ultrapure water The residual water in the cartridge was expelled with air before use The first mL of eluent were discarded and the next mL were retained for analysis Then mL of o-phenylenediamine (3.33 mg/mL) was added and the vial was placed in an ice tray in darkness for 80 before injection After 80 min, the mixture was passed through a 0.45 lm filter (Vertipure Nylon syling, USA) into the amber vial and then was injected into HPLC system The latter was equipped with reverse phase C18 column (SymmetryÒ C18 5l 4.6 250 mm, Waters, Ireland) The mobile phase was methanol–water (5:95, v/v) containing mM hexadecyltrimethylammonium bromide (CTAB) and 50 mM potassium dihydrogen phosphate, with pH adjusted to 4.59 The flow rate was 1.0 mL/ Detection was at 261 nm for reduced L-ascorbate and isoascorbate and at 348 mm for L-dehydroascorbate The retention times were 5.6, 10.8 and 13.5 for L-dehydroascorbate, reduced L-ascorbate and isoascorbate respectively Standards of L-ascorbate, L-dehydroascorbate and isoascorbate were purchased from Sigma Chemical Company (St Louis, MO) The results of vitamin C content were expressed as mg/100 mL of fruit juice Total phenol content was determined by spectrophotometer using Folin–Ciocalteu’s phenol reagent (Kim et al., 2002) Total 556 A Laorko et al / Journal of Food Engineering 116 (2013) 554–561 phenolic content was expressed as mg gallic acid equivalent per 100 mL of fruit juice (mg GAE/100 mL fruit juice) The DPPH free radical scavenging was determined according to the method of Gil-Izquierdo et al (2001) The results were expressed as mg of L-ascorbic acid equivalent per 100 mL of fruit juice L-ascorbic acid was used as antioxidant standard reference compound The oxygen radical absorbance capacity (ORAC) assay were carried out on a FLUO star Galaxy plate reader (fluostar optima software user manual, BMG Labtech, Germany) by using a modified method of Wu et al (2004) Table Total soluble solids (TSSs) and pH of MF-clarified pineapple juice obtained during months of storage at 4, 27 and 37 °C T (°C) Time (months) TSS (°Brix) pH 4 6 12.8(±0.1) 12.8(±0.2) 12.8(±0.2) 12.7(±0.2) 12.5(±0.2) 12.5(±0.1) 12.5(±0.1) 12.8(±0.1) 12.7(±0.2) 12.5(±0.3) 12.5(±0.1) 12.5(±0.1) 12.5(±0.1) 12.6(±0.2) 12.8(±0.1) 12.6(±0.1) 12.6(±0.3) 12.6(±0.2) 12.7(±0.1) 12.7(±0.1) 12.6(±0.2) 3.64(±0.04) 3.61(±0.07) 3.61(±0.07) 3.69(±0.08) 3.68(±0.04) 3.66(±0.03) 3.58(±0.08) 3.64(±0.04) 3.65(±0.01) 3.64(±0.01) 3.62(±0.04) 3.60(±0.03) 3.59(±0.04) 3.59(±0.05) 3.64(±0.02) 3.61(±0.05) 3.61(±0.02) 3.58(±0.04) 3.56(±0.06) 3.63(±0.01) 3.61(±0.07) 27 2.5 Kinetic considerations and shelf-life determination Zero and first order models have been used to evaluate the degradation of quality (e.g vitamin C, total phenol content and antioxidant capacity) This kinetic is presented by the following equations (Ross, 1998); C ¼ C ktị 3ị C ẳ C expktị 4ị where C is the content or value at time t, C0 is the initial content or value (t = 0), k is the reaction rate constant and t is the storage time The Arrhenius relationship was assumed of the temperature dependence for the reaction rate constant as follows; k ¼ A0 expðEa =RTÞ ð5Þ where Ea is the activation energy of the reaction (cal/mol), R is the ideal gas constant (1.986 cal/mol K), T is the absolute temperature (K), and A0 is the pre-exponential constant A plot of the log of rate constant for the test temperature versus the reciprocal of the absolute temperature gives the straight line if the Arrhenius relation is applied to the specific reaction The energy of the activation (Ea) was derived from the slope (Ea/R) The intercept, however, gives the exponential constant To study the influence of temperature on reaction rate, the Q10 values were calculated according to the following relationship: Q 10 ẳ k2 =k1 ị10=T T ð6Þ The obtained data were subjected to analysis of variance (ANOVA) and mean comparison were carried out using Duncan’s Multiple Range Test (DMRT) Results and discussion 3.1 Change in total soluble solid, pH and color during storage The physicochemical properties of MF-clarified pineapple juices during storage at various temperatures are shown in Table The total soluble solids and pH of MF-clarified pineapple juice ranged from 12.5 to 12.8 °Brix and 3.56–3.69, respectively It was evident that the storage time and temperature did not affect the total soluble solids content and pH of MF-clarified juices (P > 0.05) Similar results were reported for other MF-clarified juices, (Cortés et al., 2008; Esteve et al., 2005; Martin et al., 1995) The change in color of MF-clarified pineapple juice stored at 4, 27, and 37 °C were also monitored over months The changes in color of MF-clarified pineapple juice across the duration of the shelf-life study are shown in Fig.1 The L value of clarified juice stored at °C was much higher than those stored at 27 °C and 37 °C (P < 0.05) The decrease in Lvalues suggested that the clarified juices turned darker due to the non-enzymatic browning reaction during temperature-abused storage The a value did overall not significantly change during storage at different temperature 37 Parentheses following mean values indicate standard deviations levels (P > 0.05) whereas the b value gradually increased with storage time and temperature (P < 0.05) The observed increase in yellowness was comparable to the decrease of L values The overall color changes in MF-clarified juice stored at °C were less noticeable than those stored at 27 and 37 °C Table shows the chroma and the total color differences (DE) of MF-clarified juice during storage The chroma of MF-clarified juice, stored at 27 and 37 °C increased significantly with time (P < 0.05) The total color differences (DE) was significantly increased as the storage time and temperature increased (P < 0.05), which may have been due to the non-enzymatic browning Choi et al (2002) recommended that DE of would be a noticeable visual difference The color change due to non-enzymatic browning during storage of MF-clarified pineapple juice was also determined by measurement of absorbance at 420 nm, known as browning index Fig shows the absorbance at 420 nm of MF-clarified juice The browning index of clarified juice increased significantly with the storage time (P < 0.05) In addition, the storage temperature also affected the browning index during storage It was evident that the browning index of the juice stored at 27 and 37 °C were higher than that of the juice stored at °C However, there was not much difference detected in the browning index of the clarified juice stored at 27, and 37 °C Similar results were observed during storage of peach juice, stored at 3, 15, 30 and 37 °C (Buedo et al., 2001) In addition, Lee and Chen (1998) also found that the results of browning measurements are in accordance with vitamin C reduction Nevertheless, there are numbers of deterioration reactions leading to the change in color of the juice during storage such as ascorbic acid degradation, microbial spoilage, and HMF formation and off–flavor (Nagy and Randall, 1973) However, it is important to bear in mind that the advanced stages of Maillard reaction can also give rise to compounds responsible for the development of off-flavor and color changes that could affect the sensorial and quality of MF-clarified pineapple juice during storage 3.2 Stability of total phenol and antioxidant capacity during storage To the best of our knowledge, this is the first study in which the changes in phytochemical properties of MF-clarified pineapple juice during storage are reported Variation in the content of total 557 A Laorko et al / Journal of Food Engineering 116 (2013) 554–561 Table Chroma and color difference (DE) of MF-clarified pineapple juice obtained during months of storage at 4, 27 and 37 °C T (°C) Time (months) Chroma 4 6 7.87(±0.41) 8.32(±1.33) 9.03(±0.77) 11.20(±0.55) 11.82(±0.85) 12.64(±0.62) 11.36(±0.55) 7.87(±0.42) 24.26(±0.41) 27.24(±1.59) 24.63(±1.44) 30.00(±0.55) 31.00(±0.57) 31.75(±0.13) 7.87(±0.41) 27.91(±0.41) 32.49(±1.89) 31.17(±0.48) 33.48(±1.29) 35.60(±1.07) 38.06(±0.51) 27 37 Color difference (DE) 1.90(±0.74) 1.89(±0.42) 3.66(±0.79) 4.44(±1.15) 5.22(±0.73) 4.33(±0.75) 17.76(±0.15) 21.67(±1.98) 19.56(±0.45) 25.25(±0.40) 25.89(±1.01) 27.57(±0.94) 21.65(±0.22) 26.81(±1.20) 26.28(±1.06) 28.70(±0.48) 30.88((±0.56) 38.06(±0.51) Parentheses following mean values indicate standard deviations Fig L(a), a(b) and b(c) values of MF-clarified pineapple juice obtained during storage at 4, 27 and 37 °C phenol and antioxidant capacity of MF-clarified pineapple juice are shown in Figs and The initial total phenol content of MF-clarified pineapple juice was 68.71 ± 1.67 mg/100 mL (Fig 3) During months of storage at 4, 27 and 37 °C, the total phenols content of MF-clarified juice decreased with storage time (P < 0.05) It was probably due to polyphenolic oxidation and polymerization reaction, reducing the number of free hydroxyl groups measured by the Folin–Ciocalteu assay (Klopotek et al., 2005; Pacheco-palencia et al., 2007) Similar results were reported by Klimczak et al (2007) However, the colder storage temperature (4 °C) could have retained the total phenol content better than at higher storage temperature levels (27, 37 °C) During months of storage at 4, 27 and 37 °C, the loss of total phenol content in MF-clarified juice were 11.2%, 14.9% and 15.3%, respectively For the antioxidant capacity, the initial content of DPPH free radical scavenging of clarified juice were in the range of 28.70 ± 0.78 mgAAE/100 mL fruit juice while the content of the Fig Browning index of MF-clarified pineapple juice obtained during storage at 4, 27 and 37 °C ORAC assay were in the range of 321.57 ± 5.81 lmTE/100 mL fruit juice The antioxidant capacity of all samples decreased as storage time and/or storage temperature increased (P < 0.05) The presented results are in the line with the data obtained by Klimczak et al (2007) They found the decrease in antioxidant capacity of orange juice, after months of storage at 18, 28 and 38 °C were 18%, 45% and 84% respectively It is important to note that the antioxidant degradation of MF-clarified pineapple juice was lower than those found in orange juice The decrease in antioxidant capacity was related to the observed losses of total vitamin C A slight decrease in antioxidant capacity was observed during months of storage The trend of the decrease in ORAC values was similar to the findings obtained for DPPH free radical scavenging In addition, the antioxidant capacity of the juice also had positive correlation with vitamin C content This result was in accordance with the study of the degradation of phytochemical properties in jackfruit during storage (Saxena et al., 2009) The correlation of vitamin C between DPPH scavenging activity and ORAC assay is shown in 558 A Laorko et al / Journal of Food Engineering 116 (2013) 554–561 Fig Total phenol content of MF-clarified pineapple juice obtained during storage at 4, 27 and 37 °C Fig The correlation between vitamin C and DPPH scavenging activity and ORAC assay of MF-clarified pineapple juice obtained during storage at 4(e), 27(s) and 37(4) °C decrease in L-ascorbic acid (data not shown) These results suggested that the DPPH assay could be used to indicate the loss of L-ascorbic acid more accurately than the ORAC method 3.3 Stability of total vitamin C during storage At the initial of storage time, the content of vitamin C of MFclarified pineapple juice was 26.32 ± 1.32 mg/100 mL This value was slightly less than that found in the fresh pineapple juice (28.67 ± 1.8 mg/100 mL) The results indicated that MF is an effective method that retains vitamin C in pineapple juice Vitamin C content sharply decreased (P < 0.05) during the first month of the storage (Fig 6), presumably, due to the complete degradation of L-ascorbic acid while the dehydroascorbic acid can still be maintained in the juice Choi et al (2002) found similar results when they studied the ascorbic acid retention in blood orange juice during refrigerated storage The researchers found, that the L-ascorbic acid completely degraded within weeks In the present study, the reduction of vitamin C content stored at months and at 4, 27 and 37 °C of clarified pineapple juice were 60.7%, 70.3% and 74.8%, Fig Antioxidant capacity (DPPH(a), ORAC(b)) of MF-clarified pineapple juice obtained during storage at 4, 27 and 37 °C Fig The loss of vitamin C during the first month of storage could not be detected by DPPH but ORAC It was evident that the loss of vitamin C content at the first month of storage was due to a sharp Fig Vitamin C of MF-clarified pineapple juice obtained during storage at 4, 27 and 37 °C 559 A Laorko et al / Journal of Food Engineering 116 (2013) 554–561 respectively The storage temperature of °C allowed better total vitamin C retention than the other higher storage temperatures The reduction in vitamin C of thermally-pasteurized orange juice was much higher than that in MF-clarified pineapple juice (Zheng and Lu, 2011) The decrease in vitamin C content during storage was observed by many studies (Polydera et al., 2003; Klimczak et al., 2007; Piljac-Zegarac et al., 2009; Lee and Chen, 1998) According to the literature, the vitamin C content in the juice decreased during storage is dependent on the storage conditions such as temperature, oxygen, and light access On the other hand, the great reduction of vitamin C might be due to the presence of oxygen in the head space of the glass bottle Oxygen is usually responsible for the loss of vitamin C during storage Vitamin C retention has been used as indicator of shelf-life for fruit juice It has been accepted that the shelf-life of the fruit juice could be determined by 50% loss or the half-life of the vitamin C (Shaw, 1992; Odriozola-Serrano et al., 2008) 3.4 Kinetic study of vitamin C, total phenol content, antioxidant capacity and color The changes in color, vitamin C, total phenol and antioxidant capacity (DPPH and ORAC assay) during storage were chosen for the kinetic study The reaction was first determined by plotting the amount of remaining parameter values versus time (in months) at different temperatures A plot yielding either a straight line or exponential curve was obtained, indicating that the Table Microbiological quality of MF-clarified pineapple juice obtained during months of storage at 4, 27 and 37 °C Time (months) Temperature (°C) 27 37 27 37 27 37 27 37 27 37 27 37 Total plate counts (CFU/ mL) Yeast & mold counts (CFU/ mL) Colifrom counts (MPN/ mL)