Effect of packaging materials and storage temperature

Food Packaging and Shelf Life 12 (2017) 83–90

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Effect of packaging materials and storage temperature on the retention of physicochemical properties of vacuum packed pink guava powder

MARK

⁎

Mohammad Rezaul Islam Shishira, Farah Saleena Taipa, , Md. Saifullahb, Norashikin Ab. Aziza, Rosnita A. Taliba a b

Department of Process and Food Engineering, Universiti Putra Malaysia (UPM), 43400 Serdang, Selangor, Malaysia Department of Agro Product Processing Technology, Jessore University of Science and Technology, Jessore, 7408, Bangladesh

A R T I C L E I N F O

A B S T R A C T

Keywords: Pink guava powder Packaging materials Vacuum packing Physicochemical properties Shelf life

Storage shelf life of fruit powder is an important concern in fruit powder industry. The objective of this study was to explore the effect of storage conditions on the retention of physicochemical properties of guava powder. The spray-dried guava powder was packed by LDPE, PET laminated and OPP laminated film and stored at 5 °C and 25 °C for 10 weeks. The shelf life prediction was measured from the linear regression kinetic equation of water activity. Packaging film, storage temperature and time had significant effect on powder properties. PET laminated film showed the most significant effect in retention of moisture, water activity and lycopene. LDPE packed powder was the least effective in moisture control, which led to increase of glass transition temperature (Tg) and degree of caking (CD) and loss of color and lycopene. Higher storage temperature (25 °C) considerably increased the moisture gain, water activity, Tg and CD. The suitable storage condition for guava powder was PET laminated film at 5 °C that showed the maximum predicted shelf life (34.95 weeks) with the highest lycopene retention (74.56%) and low moisture content of < 3%.

1. Introduction Fruit powder products are very sensitive to moisture content, which influences the color, flavor, nutritional content and antioxidant stability. Studies on powder products as a function of moisture content or water activity have allowed the development of mathematical models to predict the physicochemical changes of powder product over time (Venir, Munari, Tonizzo, & Maltini, 2007). Changes in moisture content indicate water mobility and the degree of plasticization of larger food molecules, which also affect the rates of chemical reaction (Labuza & Altunakar, 2007). Spray-dried fruit juice powders have some problematic behaviors, such as they readily become sticky at high relative humidity or high temperature, which leads to caking phenomenon as a result of plasticization of the concentrated solvents present in the product. It occurs due to the water absorption onto the surface or increase of temperature (Anglea, Karathanos, & Karel, 1993). It also depends on the surface behaviors or surface forces of the powder particles such as, electrostatic and Van der Waals, allow the particles to stick together by emerging a liquid bond. Caking of powder particles is also affected by glass transition temperature, besides its storage temperature (Adhikari, Howes, Bhandari, & Truong, 2001). Lycopene can also be measured as a valuable quality index for pink guava

⁎

Corresponding author. E-mail address: [email protected] (F.S. Taip).

http://dx.doi.org/10.1016/j.fpsl.2017.04.003 Received 9 October 2016; Accepted 4 April 2017 2214-2894/ © 2017 Elsevier Ltd. All rights reserved.

powder, and reports show that different storage conditions may cause degradation of lycopene (Anguelova & Warthesen, 2000; Liu, Cao, Wang, & Liao, 2010). There might be a vital correlation between caking formation and lycopene degradation during the storage period of time. The deterioration of fruit powders during storage happens due to the most common factors, such as temperature, humidity, oxygen, light and water activity. The food quality during storage may change to such extent that it may be harmful to the consumer, and may lose its acceptance. Hence, protection is thought as the final step in the product development process, which ensures the entire quality of a product until the utilization by consumer for a certain period (Labuza & Altunakar, 2007). Davoodi, Vijayanand, Kulkarni, and Ramana (2007) suggested using metalized polyester bags to protect product against light, oxygen, and humidity and retard the quality changes of tomato powder during storage period. Pua et al. (2008) investigated that laminated ALP film was better in color retention, moisture control, overall acceptability of odor and taste than the laminated BOPP. Previous studies had been reported on the development of pink guava powder by spray drying (Patil, Chauhan, & Singh, 2014; Shishir, Taip, Aziz, & Talib, 2014; Shishir, Taip, Aziz, Talib, & Sarker, 2016). However, there is still room to study on the storage stability of pink


M.R.I. Shishir et al.

The water activity by 0.4 was considered as standard parameter to predict the powder shelf life (Marques, Ferreira, & Freire, 2007).

guava powder in order to investigate the effect of different storage conditions on moisture properties leading to the happening of caking formation and lycopene degradation. Therefore, the aim of this study was to explore the effect of packaging conditions and storage temperature on the retention of physicochemical properties of developed pink guava powder. This fundamental exploration is beneficial to the industrial packaging and storage of spray-dried fruit and vegetable powders.

2.4. Assessment of physicochemical properties of pink guava powder The moisture content analysis was conducted using the method of AOAC (1990). One gram of sample was carefully measured and dried in a vacuum oven at 70 °C until constant weight was obtained and the analysis was performed in triplicate. Around 2 g of powder was taken to determine the water activity by using electronic water activity meter (FA-ST Lab, GBX Instrumentation Scientifique, Romans Sur Isere, France) at approximately 25 °C (Zhang, Jiao, Lian, Deng, & Zhao, 2015). The glass transition temperature of the powders was determined by using differential scanning calorimeter (DSC 7, Perkin Elmer, Massachusetts, USA). The powder (around 5–10 mg) was scanned in a hermitically sealed 20 μl DSC aluminum pan. The purge gas used was dry nitrogen (20 ml/min). All analyses were done in triplicate. The rate of thermal scanning was carried out in 2 steps, such as i) Isothermal at −20 °C for 1 min; and ii) Heat scanning from −20 °C to 250 °C at 10 °C/min (Shrestha, Ua-arak, Adhikari, Howes, & Bhandari, 2007). In order to determine hygroscopicity (Caparino et al., 2012), the powder sample (2 g) was spread on a petri dish with three replicates and put in an airtight container containing saturated sodium chloride solution (75 ± 1% humidity) at 25 °C for seven days. Hygroscopicity was calculated as grams of adsorbed moisture per 100 g of dry solids. Degree of caking was determined following by Goula and Adamopoulos (2008). After hygroscopicity determination, the wet sample was placed in oven dryer at 70 °C for 3 h and subsequently the dried sample was cooled, weighted and transferred into 500 μm sieve and manually shaken. The remaining powder sample on the sieve was measured to determine the degree of caking as following equation:

2. Materials and methods 2.1. Materials Pink guava juice was obtained from Sime Darby Beverages Pvt. Ltd., Perak, Malaysia and maltodextrin DE 10 from Bronson & Jacobs Pvt. Ltd., Sydney, Australia. The lycopene analytical standard (≥85% purity) was purchased from Sigma-Aldrich Chemie GmbH (Seelze, Germany), and n-hexane (95% purity), acetone (99.5% purity) and dichloromethane (99.8% purity) from Friendemann Schmidt (Parkwood, Australia), and ethanol (99.9% purity, Merch KGaA, Darmstadt, Germany) were used HPLC-grade solvents. HPLC-grade mobile phases, such as acetonitrile (99.9% purity), methanol (99.8% purity) and 2-propanol (99.8% purity) from Friendemann Schmidt (Parkwood, Australia) were collected. Packaging materials, such as low density polyethylene (LDPE), laminated OPP (OPP/MPET/LLDPE) and laminated PET (PET/MPET/LLDPE) were collected from Syarikat Hang Tuah Company Ltd., Penang, Malaysia. The laminated OPP made by oriented poly propylene (OPP, 30 μm), metalized polyester (PET, 12 μm) and linear low density poly ethylene (LLDPE, 40 μm). The laminated PET made by polyester (PET, 12 μm), metalized polyester (PET, 12 μm) and linear low density poly ethylene (LLDPE, 50 μm). 2.2. Powder production

Degree of caking , CD (%) = The pink guava juice was diluted with distilled water at a ratio of 1:1 and subsequently sieved through a 250 μm sieve, followed by the addition of maltodextrin to the juice sample at concentrations of 17% (w/v) and homogenized at 5000 rpm for 8 min prior to adequate mixing (Carrillo-Navas et al., 2011) using Homogenizer (Wise Mix HG-15A, Daihan Scientific, Co. Ltd., Wonju, South Korea). In every case, 1 litre sample was subjected to spray drying using a spray dryer (Lab plant SD-05, Lab plant UK Ltd., North Yorkshire, UK) at inlet air temperatures of 150 °C, feed flow rate of 350 ml/h, outlet temperature of 90 ± 1 °C, air flow rate of 47 ± 1 m3/h and compressor air pressure of 2.1 ± 1 bar. The spray drying sample formulation and drying conditions were selected from our previous optimization study (Shishir et al., 2016).

(100 − a ) b

(1)

Where, a = Amount of powder used in sieving, b = Amount of powder remained on the sieve after sieving. The lycopene content was extracted following by Sommano, Caffin, Mcdonal, and Cocksedge (2013). First, the 0.5 g powder sample was reconstituted in 10 ml of distilled water. Then, the extraction solvents of 10 ml of hexane–acetone–ethanol (2:1:1) and 5 ml of water were added and shaken at 200 rpm for 10 min using the Wise Cube Shaking Incubator (WIS-20R, Daihan Scientific Co. Ltd., Wonju, Korea). Then, the solution was centrifuged at 12,000 × g for 10 min using a centrifuge (5804 R, Eppendorf AG, Hamburg, Germany). The upper layer was collected and evaporated. The residue was re-dissolved in 2 ml dichloromethane and subsequently filtered through a 0.45 μm membrane filter and stored at −20 °C for HPLC analysis. The lycopene content was determined using HPLC (Waters 2996, Waters Ltd., Hertfordshire, UK) and 5 μm column (X-select HSS T3, Waters Ltd., Hertfordshire, UK). An isocratic mobile phase system of acetonitrile: methanol: 2-propanol (44:54:2 by vol.) was used followed by Anguelova and Warthesen (2000). The column temperature was set at 25 °C, flow rate at 1.5 ml/min and wavelength at 472 nm. The lycopene content was calculated using a standard calibration curve prepared at concentrations of 0.108 to 1.733 mg/ml. The powder morphology was investigated through scanning electron microscope (SEM) analysis using scanning electron microscope (JSM-6400, Jeol, Japan). Small amount power was mounted on platinum coated SEM stubs. The SEM analysis was carried out at an accelerating voltage of 15 kV and the micrographs were captured at a magnification of × 4000, × 5000 and × 7000 at scale bar of 14 mm and 1 μm. The color of the final product was measured carefully by using a color reader (CR-10; Konica Minolta Sensing Ltd., Japan) (Kha, Nguyen, and Roach, 2010).

2.3. Packaging, storage and shelf life of pink guava powder The produced pink guava powder was packed using three types of packaging materials, such as low density polyethylene (LDPE) as a control sample, laminated OPP (OPP/MPET/LLDPE) and laminated PET (PET/MPET/LLDPE). The pink guava powder (10 g) was filled in 10 cm × 7 cm pouches of LDPE, laminated OPP and laminated PET. The pouches of laminated OPP and laminated PET were carefully sealed using vacuum sealer (Vac Master SVP-40, ARY Inc., USA) and the LDPE was used as controlled sample and sealed with impulse sealer without vacuum treatment. The pink guava powder pouches were placed in vertical pouch holder to avoid the pouch contact and expose to the same environment. The pouches were stored at 5 °C and 25 °C for 10 weeks. The LDPE sample (control) stored at 25 °C. The data were collected every two weeks. The relative humidity of storage environment was monitored at around 50 ± 1% in 5 °C storage condition and 65 ± 5% in 25 °C storage condition. The shelf life prediction was measured from the linear regression kinetic equation of water activity. 84



Table 1 Physicochemical properties of the spray-dried pink guava powder before storage. Powder properties

Quantity

Moisture content (%) Water activity Bulk density (kg/m3) Tapped density (kg/m3) Particle size (μm) Hygroscopicity (%) Glass transition temperature (°C) Lycopene content (μg/100 g) Color measurement Lightness, L* Color ratio, a*/b* Hue angle, h*

3.08 ± 0.13 0.33 ± 0.01 502 ± 9.2 570 ± 10.5 11.78 ± 0.65 22.63 ± 1.67 209.9 ± 1.5 54.70 ± 0.10

Table 2 Significant level (p value) of storage conditions and their interactions on powder properties.

+62.80 ± 0.28 +0.383 ± 0.01 +69.00 ± 0.15

2.5. Statistical analysis

Powder properties

Packaging film (P)

Storage tempt. (T1)

Storage time (T2)

P × T1

P × T2

T1 × T2

Moisture Water activity Glass transition tempt. Degree of caking Lycopene Lightness Hue angle Color change

0.004** 0.002** 0.104NS

0.001** 0.001** 0.003**

0.001** 0.001** 0.001**

0.03* 0.45 NS 0.42 NS

0.14 NS 0.03* 0.34 NS

0.001** 0.001** 0.02*

0.041*

0.007**

0.001**

0.58

NS

0.93

NS

0.08

0.02* 0.005** 0.002** 0.007**

0.001** 0.001** 0.001** 0.001**

0.001** 0.001** 0.001** 0.001**

0.09 0.15 0.11 0.10

NS

0.53 0.24 0.14 0.33

NS

0.01** 0.004** 0.001** 0.001**

NS NS NS

NS NS NS

NS

NB: P × T1 = Interaction between packaging film and storage temperature, P × T2 = Interaction between packaging film and storage time, P × T2 = Interaction between storage temperature and time. * Indicates significant at p < 0.05, NS indicates non-significant. ** Indicates significant level at p < 0.01.

The data was analyzed by analysis of variance (ANOVA) and Duncan’s multiple range test using SAS 9.3 TS L1M2. All the measurements were performed in triplicate and calculated the mean value and standard deviations. The figures of mean value and error bars were made by using Microsoft excel version of 2010.

3. Results and discussion 3.1. Powder properties of the developed spray-dried pink guava The spray-dried pink guava powder produced at 150 °C with 17%

Fig. 1. Effect of storage conditions on pink guava powder properties: (a) moisture content, (b) water activity and (c) glass transition temperature during the storage period of 10 weeks.

85



Fig. 2. Effect of storage conditions on pink guava powder properties: (a) lycopene retention and (b) degree of caking during the storage period of 10 weeks.

of pink guava powder was significantly (p < 0.01) affected by the packaging films and storage temperature during the storage of 10 weeks (Table 2). The moisture gain of control powder packed by LDPE was noticeably high by around 5.87% after 10 weeks, whereas, the moisture gain was less in other packaging films, such as OPP and PET showed 3.8 times and 5.19 times less moisture gain, respectively, at 25 °C and OPP and PET showed 7.82% times and 9.17% times less moisture gain, respectively, at 5 °C. The LDPE film allows high permeability to moisture transfer from external environment into the product as compared with OPP and PET films (Robertson, 2010). Fig. 1(a) showed that the PET film allowed less moisture gain (1.13%) during storage period than the OPP film (1.53) at 25 °C, but they were almost close (0.64% by PET and 0.75% by OPP), when stored at 5 °C. This was due to the high moisture permeability of OPP than the PET film, that was influenced at higher temperature of 25 °C (Moraes, Rosa, & Pinto, 2008; Robertson, 2010). In contrast, the moisture gain increased at higher storage temperature during the storage period. This might be due to the significant interaction (p < 0.01) between storage temperature and storage time. The OPP film showed 0.78% increase of moisture gain and PET showed 0.49% increase of moisture gain, when stored at 25 °C compared to storage temperature 5 °C (Fig. 1a). Henríquez, Córdova, and Saavedra, (2013) observed, moisture content of apple peel powder increased significantly, when the storage temperature increased from 4 °C to 25 °C. LDPE sample showed a sharp increase of water activity by around 0.119, which was similar with the trend of powder moisture gain packed by LDPE (Fig. 1.b). Similar upward parallel relationship between moisture content and water activity has been proven by several studies (Corey, Kerr, Mulligan, & Lavelli, 2011; Dak, Sagar, & Jha, 2014; Moraes et al., 2008). The water activity of OPP and PET samples increased up to 0.369 and 0.363, respectively, at 25 °C and 0.346 and 0.342, respectively at 5 °C (Fig. 1.b). Similarly, the water activity trends of OPP and PET were closely correlated with the moisture gain trends of OPP and PET samples. Although, there was no noticeable difference between the water activity of OPP and PET samples, the storage temperature showed particular effect on water activity. The increase of storage temperature from 5 °C to 25 °C increased the water activity by 0.023 and 0.021 in OPP and PET samples, respectively (Fig. 4.1.b). Water activity is also related with equilibrium relative humidity (ERH). When the ERH of a product is lower than the relative humidity of storage environment, the product naturally tends to pick up the moisture (Subramaniam, 2009). The relative humidity was around 50 ± 1% and 65 ± 5% at 5 °C and 25 °C of storage condition, respectively, which might also be the reason of increasing moisture content and water activity of pink guava powder. Pua et al. (2008) showed that the moisture gain increased with the increasing relative humidity in all types of packaging samples. There was a remarkable difference between LDPE sample and OPP and PET samples in terms of the numerical value of moisture properties. This

Fig. 3. Correlation of Moisture content versus Degree of caking (%) and Moisture content versus Lycopene retention (LC) for LDPE packed powder during the storage period of 10 weeks.

Maltodextrin (w/v) had the maximum lycopene retention from optimization study (Shishir et al., 2016) was analyzed for the physicochemical properties before undertaking the shelf life stability investigation. Table 1 showed that the moisture content and water activity is 3.08% and 0.33, respectively, which are standard for the storage of fruit powder (Marques et al., 2007; Tan, Ibrahim, Kamil, & Taip, 2011). Hygroscopicity is around 22.63%, which is similar to the findings of Dea, Germer, Cozero, and Cristhiane (2012) shows the powder is moderately hygroscopic (Murikipudi, Gupta, & Sihorkar, 2013). The glass transition temperature (Tg) more than 200 °C indicates that the powder could be stored for long time under specified condition (Bhandari, Datta, & Howes, 1997). According to color property (Table 1), lightness (62.8 °) refers the powder is in between of black and white region and hue angle (69 °) indicates the powder is in between of red and yellow with a favor of yellow region (Duangmal, Saicheua, & Sueeprasan, 2008). 3.2. Effect of packaging films and storage temperature on powder properties 3.2.1. Moisture properties and glass transition temperature Low levels of moisture content (2–4%) and low levels of water activity (0.2–0.4) are considered as basic reference parameters for the commercialization of food powders or dehydrated foods, since they indicate the microbiological and oxidative stability of the product against browning and hydrolitical reactions, lipid oxidation, autooxidation and enzymatic activity (Marques et al., 2007; Tan et al., 2011). The effect of packaging films and storage temperature on the powder moisture content is shown in Fig. 1(a). The moisture content 86



Fig. 4. The morphology of powder stored at LDPE, OPP and PET laminate films at 25 °C and 5 °C.

indicated around 82% loss of its initial amount from 0 week to 10th week (Fig. 2.a). LDPE is poor as a barrier of oxygen permeability, which allows the oxygen to migrate from environment to product (Robertson, 2010) and allows to cause oxidative reaction with lycopene and chemical changes or molecules split of lycopene as a consequence of lycopene lose (Shi, Mazza, & Le-Maguer, 2002). As LDPE is transparent; lycopene loss may also be due to the light effect. Sharma and Le Maguer (1996) reported that the loss of lycopene was by 97% and 73.3-78.9% in freeze-dried and oven-dried tomato pulp powder, respectively, stored in a closed container (without vacuum) during the storage of 4 months, and reasoned to the air and light effect, caused the lycopene loss in faster rate. According to the report of Anguelova and Warthesen (2000), around 30% of lycopene loss in tomato powder occurred by light exposure or light oxidation. In contrary, the loss of lycopene over the storage period was found by around 42% and 25.5% in OPP samples at 25 °C and 5 °C, respectively, which was 1.95 times and 3.2 times, respectively, less lycopene loss than the LDPE samples. Similarly, PET samples showed the lycopene loss of around 38.5% and 25.5% at 25 °C and 5 °C, respectively, which was 2.13 times and 3.21 times less lycopene loss, respectively (Fig. 2.a). This is due to the good barrier properties of OPP and PET than LDPE against oxygen transfer (Robertson, 2010). However, storage temperature of 5 °C showed better lycopene retention than the storage temperature of 25 °C by around 16.5% and 13.0% more

was due to the sample preparation; because, the LDPE sample was not vacuum packed, while the OPP and PET samples were vacuum treated. The vacuum treatment reduced the moisture content by 1.06% and water activity by 0.024 of OPP and PET samples at storage of 0 week (Fig. 1). Glass transition temperature (Tg) significantly decreased with the increase of moisture content and water activity (Fig. 1.c). In the case of LDPE sample, the increase of moisture content of around 6% during the storage period led to reduce the Tg of around 80 °C (Fig. 1). According to Ellis (1988), an increase of small amount of moisture content (even 1%) can dramatic decrease of Tg as found 15–20 °C. This is because, water is the lowest molecular weight solvent having Tg of −135 °C, which plays significant role to reduce the Tg (Roos, 1995). The Tg of OPP and PET packed powders slowly decreased until 4th week by around 1 °C of Tg, which was correlated with the less moisture gain of powder packed by OPP and PET until 4th week. However, the packaging films (OPP and PET laminated) were effective to keep the Tg at 5 °C storage temperature during the storage period (Fig. 1.c). 3.2.2. Lycopene retention and caking phenomenon Fig. 2(a) shows that the lycopene retention reduced with the increase of storage time over 10 weeks. The lycopene loss was quite sharp in LDPE sample during storage period by around 41.46 mg/ 50.24 mg of lycopene contained in 100 g of pink guava powder, which 87



Table 3 Color properties at different storage conditions. Storage tempt.

Packaging film

Storage time (week)

Lightness

25 °C

LDPE (Control)

0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10

62.80 63.96 64.76 65.13 65.63 66.23 62.80 63.13 64.00 64.23 64.50 64.73 62.80 63.10 63.83 64.13 64.20 64.50

± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

0.28 0.84 0.54 1.17 0.72 0.74 0.28 1.35 0.17 0.49 0.35 0.37 0.28 0.31 0.08 0.68 0.94 0.40

8.33 7.80 7.46 7.16 6.83 6.43 8.33 8.00 7.73 7.56 7.50 7.30 8.33 8.03 7.80 7.70 7.63 7.53

± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

0 2 4 6 8 10 0 2 4 6 8 10

62.80 63.03 63.63 63.86 63.90 64.10 62.80 63.00 63.50 63.76 63.86 64.06

± ± ± ± ± ± ± ± ± ± ± ±

0.28 0.68 0.32 0.46 0.26 0.83 0.28 0.57 0.64 0.39 0.27 0.80

8.33 8.10 7.96 7.76 7.73 7.63 8.33 8.13 7.96 7.86 7.76 7.70

± ± ± ± ± ± ± ± ± ± ± ±

OPP

PET

5 °C

OPP

PET

Redness

Chroma

Hue angle

Color difference

0.03 0.02 0.06 0.06 0.14 0.14 0.03 0.26 0.29 0.08 0.17 0.05 0.03 0.14 0.20 0.23 0.20 0.12

23.2 ± 0.05 22.9 ± 0.25 22.8 ± 0.2 22.4 ± 0.41 22.2 ± 0.06 21.7 ± 0.14 23.2 ± 0.05 23.03 ± 0.43 22.8 ± 0.11 22.6 ± 0.35 22.4 ± 0.17 22.1 ± 0.38 23.2 ± 0.05 23.03 ± 0.18 22.9 ± 0.35 22.7 ± 0.26 22.5 ± 0.79 22.2 ± 0.26

69.00 ± 0.15 69.63 ± 0.85 70.83 ± 0.18 71.73 ± 0.02 72.20 ± 0.26 73.06 ± 0.26 69.00 ± 0.15 69.73 ± 0.35 70.1 ± 0.2 70.4 ± 0.37 70.63 ± 0.49 71.2 ± 0.2 69.00 ± 0.15 69.7 ± 0.26 69.96 ± 0.27 70.26 ± 0.26 70.53 ± 0.12 71.1 ± 0.68

0 1.82 2.57 3.03 3.67 4.39 0 1.13 1.54 2.26 2.65 3.11 0 0.93 1.33 1.92 2.59 2.83

0.03 0.17 0.14 0.06 0.02 0.14 0.03 0.08 0.14 0.08 0.03 0.05

23.2 ± 0.05 23.1 ± 0.26 22.9 ± 0.2 22.7 ± 0.15 22.6 ± 0.08 22.5 ± 0.28 23.2 ± 0.05 23.1 ± 0.23 23.06 ± 0.23 22.96 ± 0.29 22.7 ± 0.52 22.6 ± 0.08

69.00 ± 0.15 69.30 ± 0.37 69.53 ± 0.33 69.96 ± 0.37 70.3 ± 0.51 70.6 ± 0.55 69.00 ± 0.15 69.3 ± 0.11 69.5 ± 0.11 69.93 ± 0.34 70.2 ± 0.25 70.5 ± 0.05

0 0.81 1.03 1.48 1.78 2.15 0 0.79 1.01 1.46 1.66 1.92

± ± ± ± ±

0.19 1.48 1.75 0.63 0.71

± ± ± ± ±

0.15 0.35 0.03 0.41 0.38

± ± ± ± ±

0.26 0.11 0.69 0.60 0.27

± ± ± ± ±

0.2 0.47 0.49 0.30 0.43

± ± ± ± ±

0.18 0.24 0.32 0.43 0.67

Values are mean ± standard error.

increasing CD in powder caused to the increase of lycopene degradation in powder. According to the findings of Goula, Adamopoulos, Chatzitakis, and Nikas (2006), water soluble compounds react as catalyst during lycopene degradation. Thus, increasing moisture content leads to increase the caking degree and increase the catalyst effect of lycopene degradation.

Table 4 Shelf life prediction of storage powder from the linear regression kinetic equation of water activity. Powder sample

Linear regression equation

R2

Predicted shelf life (week)

LDPE at 25 °C OPP at 25 °C PET at 25 °C OPP at 5 °C PET at 5 °C

y = 0.0125x + 0.3359 y = 0.0046x + 0.3166 y = 0.0041x + 0.3169 y = 0.0025x + 0.3199 y = 0.0023x + 0.3196

0.9832 0.9355 0.9503 0.9573 0.9726

5.12 18.13 20.26 32.04 34.95

3.2.3. Particle morphology The powder particle morphology is a strong tool to determine and observe the agglomeration or caking phenomenon on the powder surface during storage (Liu et al., 2010). Fig. 4 (a) shows that the circumstances of powder particles at 0 week of storage period. The powder particles were spherical with some internal pores. Few of particles stuck together due to the particle adhesion occurred by electrostatic and Van der Waals forces (Vidovi, Vladi, Va, Zekovi, & Popovi, 2014). After 10 weeks of storage observation, it was found that the powder sample packed by LDPE (control) structurally collapsed and caused caking phenomenon and agglomeration (Fig. 4.b). The caking phenomenon involved with the plasticization of particle surface occurred due to the water absorption onto the particle surface or increase of temperature (Anglea et al., 1993). This has a linkage with the moisture gain, as it was found that the LDPE sample increasingly gained moisture during storage period and reached from 3.37% to 9.24% over 10 weeks (Fig. 1.a). In contrast, there were no significant changes of OPP and PET samples on particle morphology compared to LDPE sample. However, in compare to initial stage of powder, most of the powder particles stuck together after 10 weeks, which might be the early stage of caking phenomenon happened by the water absorption (Fig. 4.b). The particle to particle interaction or particle adhesion or particle stickiness is basically depends on the surface behaviors of the powder particles (Adhikari et al., 2001). According to SEM image report, there was no particular difference between the effects of storage temperatures on powder particles (Fig. 4.b), but based on the report of degree of caking, higher storage temperature caused higher degree of

retention in OPP sample and PET sample, respectively (Fig. 2.a). The lycopene loss at higher storage temperature is due to the temperature sensitive behavior of lycopene (Quek, Chok, & Swedlund, 2007; Shi et al., 2002). Statistical results support that interaction between storage temperature and storage time is highly significant (p < 0.01) as shown in Table 2. Supporting results has been proven by Anguelova and Warthesen (2000). They investigated that the lycopene retention in tomato powder stored at 6 °C was around 25% more than the powder stored at 45 °C, during the storage of 6 weeks. Degree of caking (CD) was significantly affected by packaging materials, storage temperature and time (Table 2). CD noticeably increased by 23% in LDPE packed powder during the storage period (Fig. 2.b), which indicates water absorbs on particle surfaces forming a saturation solution and thereby making the particles sticky and forming liquid bridges and resulting in caking phenomenon (Downton, FloresLuna, & King, 1982). In contrast, CD slowly increased in OPP and PET packed powders (Fig. 2.b), which could be referred to the high moisture barrier ability of OPP and PET films than LDPE, allowing low moisture absorption on particle surfaces during storage. Fig. 3 shows that how moisture content was correlated with CD and lycopene retention. As it can be observed that higher the moisture content of storage powder, higher the CD and lower the lycopene retention in storage powder. The 88



caking (Fig. 2.b). This was also supported by statistical findings, since storage temperature was significant on degree of caking (Table 2). On the contrary, Teunou and Fitzpatrick (1999) stated that changing the storage temperature from above freezing to 30 or 40 °C does not have major impact on powder flow-ability, which shows no significant changes in particle adhesion during storage.

Acknowledgment This work was supported by the Ministry of Education Malaysia, under the Fundamental Research Grant Scheme (Project no: 03-02-131296FR). References

3.2.4. Color features The packaging film and storage temperature showed significant effect (p < 0.01) on color properties (Table 2). The powder packed by LDPE showed noticeable increase in lightness by 3.43 °, hue angle by 4 ° and color difference by 2.57 and decrease in redness by 1.9 and chroma by 1.5 (Table 3). It indicates that the color properties had gone to loss due to the oxidative, thermal and light effect (Anglea et al., 1993; De Sousa, Borges, Magalhães, Ricardo, & Azevedo, 2008). The powder packed by OPP and PET showed less color loss than the powder packed by LDPE due to the high moisture and oxygen barrier properties and non-transparent behavior to light. The storage temperature 5 °C showed better color retention than the storage temperature of 25 °C. However, the storage condition of powder with PET film at 5 °C had the maximum color retention ability in terms of lowest changes in color difference, hue angle, lightness and redness. There might have linkage with lycopene degradation, because lycopene is responsible for the redness of pink guava powder (Sato, Sanjinéz-Argandona, & Cunha, 2006). The LDPE film showed the most poor ability to protect the color and lycopene content. In case of other films, PET packed powders were rich in color and lycopene retention both in 5 °C and 25 °C than the OPP packed powders.

AOAC (1990). Official methods of analysisMethod 934.01 (15th ed.). Gaithersburg, U.S.A: Association Official Analytical Chemists. Adhikari, B., Howes, T., Bhandari, B. R., & Truong, V. (2001). Stickiness in foods: A review of mechanisms and test methods. International Journal of Food Properties, 4(1), 1–33. Anglea, S. A., Karathanos, V., & Karel, M. (1993). Low-temperature transitions in fresh and osmotically dehydrated plant materials. Biotechnology Progress, 9(2), 204–209. Anguelova, T., & Warthesen, J. (2000). Lycopene stability in tomato powders. Journal of Food Science, 65(1), 67–70. Bhandari, B. R., Datta, N., & Howes, T. (1997). Problems associated with spray drying of sugar-rich foods. Drying Technology, 15(2), 671–684. Caparino, O. A., Tang, J., Nindo, C. I., Sablani, S. S., Powers, J. R., & Fellman, J. K. (2012). Effect of drying methods on the physical properties and microstructures of mango (Philippine “Carabao” var.) powder. Journal of Food Engineering, 111(1), 135–148. Carrillo-Navas, H., González-Rodea, D. A., Cruz-Olivares, J., Barrera-Pichardo, J. F., Román-Guerrero, A., & Pérez-Alonso, C. (2011). Storage stability and physicochemical properties of passion fruit juice microcapsules by spray-drying. Mexican Magazine of Chemical Engineering, 10(3), 421–430. Corey, M. E., Kerr, W. L., Mulligan, J. H., & Lavelli, V. (2011). Phytochemical stability in dried apple and green tea functional products as related to moisture properties. LWT − Food Science Technology, 44(1), 67–74. Dak, M., Sagar, V. R., & Jha, S. K. (2014). Shelf-life and kinetics of quality change of dried pomegranate arils in flexible packaging. Food Packaging and Shelf Life, 2(1), 1–6. Davoodi, M. G., Vijayanand, P., Kulkarni, S. G., & Ramana, K. V. R. (2007). Effect of different pretreatments and dehydration methods on quality characteristics and storage stability of tomato powder. LWT − Food Science Technology, 40, 1832–1840. De Sousa, A. S., Borges, S. V., Magalhães, N. F., Ricardo, H. V., & Azevedo, A. D. (2008). Spray-dried tomato powder: Reconstitution properties and colour. Brazilian Archives of Biology and Technology, 51(4), 807–814. Dea, R. C. D., Germer, S. P. M., Cozero, H. A., & Cristhiane, C. (2012). Study of physicochemical properties of guava and mango powder obtained by spray-drying to use as natural additives. International conference of agricultural engineering. postharvest, food and process engineering. Downton, G. E., Flores-Luna, J. L., & King, C. J. (1982). Mechanism of stickiness in hygroscopic amorphous powders. Industrial and Engineering Chemistry Fundamentals, 21, 447–451. Duangmal, K., Saicheua, B., & Sueeprasan, S. (2008). Colour evaluation of freeze-dried roselle extract as a natural food colorant in a model system of a drink. LWT – Food Science Technology, 41(8), 1437–1445. Ellis, T. S. (1988). Moisture-induced plasticization of amorphous polyamides and their blends. Journal of Applied Polymer Science, 36(3), 451–466. Goula, A. M., & Adamopoulos, K. G. (2008). Effect of maltodextrin addition during spray drying of tomato pulp in dehumidified air: ii. Powder properties. Drying Technology, 26, 726–737. Goula, A. M., Adamopoulos, K. G., Chatzitakis, P. C., & Nikas, V. A. (2006). Prediction of lycopene degradation during a drying process of tomato pulp. Journal of Food Engineering, 74(1), 37–46. Henríquez, C., Córdova, A., & Saavedra, L. M. J. (2013). Storage stability test of apple peel powder using two packaging materials: High-density polyethylene and metalized films of high barrier. Industrial Crops and Products, 45, 121–127. Kha, T. C., Nguyen, M. H., & Roach, P. D. (2010). Effects of spray drying conditions on the physicochemical and antioxidant properties of the Gac (Momordica cochinchinensis) fruit aril powder. Journal of Food Engineering, 98(3), 385–392. Labuza, T. P., & Altunakar, B. (2007). Water activity in foods: Fundamentals and applications. Ames, Iowa: IFT Press/Blackwell Publishing. Liu, F., Cao, X., Wang, H., & Liao, X. (2010). Changes of tomato powder qualities during storage. Powder Technology, 204(1), 159–166. Marques, L. G., Ferreira, M. C., & Freire, J. T. (2007). Freeze-drying of acerola (Malpighia glabra L.). Chemical Engineering and Processing: Process Intensification, 46(5), 451–457. Moraes, M. A., Rosa, G. S., & Pinto, L. A. A. (2008). Moisture sorption isotherms and thermodynamic properties of apple Fuji and garlic. International Journal of Food Science and Technology, 43(10), 1824–1831. Murikipudi, V., Gupta, P., & Sihorkar, V. (2013). Efficient throughput method for hygroscopicity classification of active and inactive pharmaceutical ingredients by water vapor sorption analysis. Pharmaceutical Development and Technology, 18(2), 348–358. Patil, V., Chauhan, A. K., & Singh, R. P. (2014). Optimization of the spray-drying process for developing guava powder using response surface methodology. Powder Technology, 253, 230–236. Pua, C. K., Hamid, N. S. A., Tan, C. P., Mirhosseini, H., Rahman, R. A., & Rusul, G. (2008). Storage stability of jackfruit (Artocarpus heterophyllus) powder packaged in aluminium laminated polyethylene and metallized co-extruded biaxially oriented polypropylene during storage. Journal of Food Engineering, 89(4), 419–428. Quek, S. Y., Chok, N. K., & Swedlund, P. (2007). The physicochemical properties of spray-

3.3. Shelf life prediction According to Marques et al. (2007), the water activity ranged from 0.2 to 0.4, ensures the microbiological and oxidative stability of the product. For the powder shelf life study, the water activity by 0.4 was considered as standard parameter to predict the powder shelf life. Table 4 shows the predicted shelf life by using linear regression equation. The maximum shelf life was found at 5 °C storage temperature in PET packed powder of 34.95 weeks and OPP packed powder of 32.04 weeks. LDPE powders were found with the lowest shelf life of 5.12 weeks. There could be few reasons, such as LDPE powders were not packed with vacuum treatment, which caused higher initial moisture content and water activity in LDPE packed powders. Another reason is LDPE film has less moisture barrier properties which allowed gaining the moisture from the environment leading to increase the water activity (Robertson, 2010).

4. Conclusion Packaging film, storage temperature and time showed significant (p < 0.05) effect on the spray-dried pink guava powder properties. The interaction between storage temperature and storage time showed significant effect on powder properties. The higher storage temperature (25 °C) significantly (p < 0.01) increased the moisture gain, water activity, Tg and CD, which caused lycopene reduction by thermal effect and oxidation. On the other hand, PET laminate film was the most effective in retention of moisture, water activity and lycopene content. LDPE packed powder was found as the least effective in moisture control, which led to increase the Tg and CD and loss of color and lycopene. The suitable condition for storage of pink guava powder was found in PET laminated film at 5 °C, which showed the highest predicted stability was around 34.95 weeks with the maximum lycopene retention of 74.56%. The findings of this study exposed the packaging and storage suitability for spray-dried fruit powder that could be beneficial from industrial to consumer level. 89



scanning calorimetry (DSC) and thermal mechanical compression test (TMCT). International Journal of Food Properties, 10(3), 661–673. Sommano, S., Caffin, N., Mcdonal, J., & Cocksedge, R. (2013). The impact of thermal processing on bioactive compounds in Australian native food products (bush tomato and Kakadu plum). Food Research International, 50, 557–561. Subramaniam, P. J. (2009). Science and technology of enrobed and filled chocolate, confectionery and bakery products. Cambridge: Woodhead Publishing Ltd. Elsevier BV. Tan, L. W., Ibrahim, M. N., Kamil, R., & Taip, F. S. (2011). Empirical modeling for spray drying process of sticky and non-sticky products. Procedia Food Science, 1, 690–697. Teunou, E., & Fitzpatrick, J. (1999). Effect of relative humidity and temperature on food powder flowability. Journal of Food Engineering, 42(2), 109–116. Venir, E., Munari, M., Tonizzo, A., & Maltini, E. (2007). Structure related changes during moistening of freeze dried apple tissue. Journal of Food Engineering, 81, 27–32. Vidovi, S. S., Vladi, J. Z., Va, G., Zekovi, Z. P., & Popovi, L. M. (2014). Maltodextrin as a carrier of health benefit compounds in Satureja montana dry powder extract obtained by spray drying technique. Powder Technology, 258, 209–215. Zhang, Y., Jiao, S., Lian, Z., Deng, Y., & Zhao, Y. (2015). Effect of single- and two-cycle high hydrostatic pressure treatments on water properties, physicochemical and microbial qualities of minimally processed squids (Todarodes pacificus). Journal of Food Science, 80(5), 1012–1020.

dried watermelon powders. Chemical Engineering and Processing: Process Intensification, 46(5), 386–392. Robertson, G. L. (2010). Food packaging and shelf life. Brisbane: Taylor and Francis Group. Roos, Y. (1995). Phase transitions in foods. San Diego: Elsevier BV, Academic Press. Sato, A. C. K., Sanjinéz-Argandona, E. J., & Cunha, R. L. (2006). The effect of addition of calcium and processing temperature on the quality of guava in syrup. International Journal of Food Science and Technology, 41, 417–424. Sharma, S. K., & Le Maguer, M. (1996). Kinetics of lycopene degradation in tomato pulp solids under different processing and storage conditions. Food Research International, 29(3–4), 309–315. Shi, J., Mazza, G., & Le-Maguer, M. (2002). Functional foods-biochemical and processing aspects. USA: Taylor and Francis Group, CRC Press. Shishir, M. R. I., Taip, F. S., Aziz, N. A., & Talib, R. A. (2014). Physical properties of spraydried pink guava (Psidium guajava) powder. Agriculture and Agricultural Science Procedia, 2, 74–81. Shishir, M. R. I., Taip, F. S., Aziz, N. A., Talib, R. A., & Sarker, M. S. H. (2016). Optimization of spray drying parameters for pink guava powder using RSM. Food Science and Biotechnology, 25, 1–8. Shrestha, A. K., Ua-arak, T., Adhikari, B. P., Howes, T., & Bhandari, B. R. (2007). Glass transition behavior of spray dried orange juice powder measured by differential

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