77
IMPROVING PEMPEK’S SHELF LIFE USING YAM’S STARCH BASED BIOPLASTICS PACKAGING WITH ADDITION OF CLOVE OIL
Ulyarti1*, Ria Amelia Yolanda1, Dian Wulansari1, Agus Salim2, Nazarudin3
1Program Studi Teknologi Hasil Pertanian – Fakultas Pertanian – Universitas Jambi Jl. Tribrata, Pondok Meja, Muaro Jambi, Jambi
2Laboratorium Terpadu – Universitas Jambi Jl. Raya Jambi Ma Bulian, Muaro Jambi – Jambi
3Program Studi Teknik Kimia, Fakultas Sains dan Teknologi – Universitas Jambi Jl. Raya Jambi Ma Bulian, Muaro Jambi - Jambi
Corresponding Author, email : [email protected]
Submitted : 13 May 2023 Revised : 21 July 2023 Accepted : 10 August 2023 ABSTRACT
This study aimed to determine the effect of yam starch and clove oil based bioplastics packaging on the microbiological and sensory properties of pempek during storage. This research was carried out by using different packaging on pempek: bioplastics and polyethylene plastic. Pempek in each group was kept for 0, 8, 16, 24, 48 hours at room temperature. The total of Staphylococcus aureus bacteria was determined using colony forming unit and the sensory properties were obtained by the determination of color, texture and aroma of pempek using 5 skilled panelists. The results showed that the use of bioplastics packaging decreased the growth of Staphylococcus aureus bacteria in pempek compared to polyethylene plastics. The decrease in acidity was in line with the growth of Staphylococcus aureus that was steeper in pempek packaged with polyethylene plastics. The use of bioplastics also maintained the sensory properties of pempek (smell of damage) during storage better than the polyethylene plastic did.
Keywords: Bioplastics, Clove Oil; Pempek; Yam’s Starch
INTRODUCTION
Pempek is a processed fish product with a chewy and elastic texture. It is usually consumed along with a sour and spicy sauce dip. Its chemical composition depends on the type of fish and its proportion in the dough. In general however, pempek contains 58.59% water, 18.26% protein, 20.17% carbohydrates, 1.41% fat and 1.57% ash. It contains high protein which is easily undergo bacterial spoilage and shorten its shelf life (Kameta et al., 2013). Pempek made out of 66.67%
fish and stored at room temperature could only last for one day.
Pratama et al. (2016) reported that pempek spoilage begins with the changes in texture, the formation of mucus on the surface, changes in color, the appearance of a foul odor and a decrease in pH. The rotten aroma in pempek is caused by
microbial activity which degrades protein into amino acids and is further degraded into Ammonia gas (NH3), Hydrogen Sulfide, Nitrogen Oxide (NO) and Sulfur Dioxide (Kameta et al., 2013)
The decrease in the quality of pempek can be inhibited by applying a packaging. Polyethylene (PE) and polypropylene (PP) plastics are the types of packaging commonly used to pack meat and fish products. The use of synthetic plastic packaging may induce a negative impact on the environment because it is difficult to degrade in nature. Some efforts can be made to reduce the environmental damage due to the use of plastic packaging, one of which is to replace them with a bioplastics packaging. A starch-based bioplastics packaging is one of the alternatives. It can be edible and easily decomposes in nature (Kamsiati et al., 2017).
78 The use of bioplastics packaging can also be enhanced into the protection of the products from microbial damage by the addition of antibacterial materials into the bioplastics. It also a good alternative to increase the durability and quality of materials during storage (Winarti et al., 2012)
Clove oil performs antibacterial ability due to its antibacterial compounds, namely flavonoids, tannins, alkaloids, and eugenol (Rukmana, 2016). Around 70-95%
eugenol is found in clove oil (Purbasari et al., 2013). According to Ulyarti et al. (2021) clove oil in bioplastics can inhibit the growth of pathogenic bacteria Staphylococcus aureus.
The use of yam’s starch and clove oil bioplastics as pempek packaging is expected to increase the shelf life of pempek by inhibiting the growth of Staphylococcus aureus bacteria in the pempek. This has been previously reported that the inhibition of Staphylococcus aureus bacteria can extend the shelf life of fish balls (Warsiki et al., 2013). This study aimed to compare the microbiological and sensory qualities of pempek packaged using yam’s starch based bioplastics with the addition of clove oil and those packaged using conventional plastics (PE) during storage.
METHODS
White yam tubers were obtained from the Bangko, Jambi Province.
Glycerols, NaCl, and BPA media were from Merck. Clove flower oil and 70% alcohol were local products and purchased online.
Mackerel, tapioca, salt, garlic were purchase from local grocery store. The tools used in this study were blender, 200 mesh sieve, 60 mesh sieve, analytical balance, kitchen tools, hot plate, thermometer, glass mould size 25x25 cm, oven, magnetic stirrer, laminar air flow, micro pipette, autoclave, incubator, pH meter and glass wares.
Research Design
This research was conducted using packaging type as the treatment. There were 2 types of packaging used, namely
bioplastics packaging and PE (polyethylene) plastic packaging. Pempek in each treatment was stored for 0, 8, 16, 24, 48 hours at room temperature. Each treatment was repeated twice.
Yam Starch Extraction (Ulyarti et al., 2018) Yam starch extraction begins by peeling the skin of the yam tuber, slicing the yam tuber to facilitate the process of removing mucus. Yam slices were soaked in 15% salt solution for 30 minutes, then washed thoroughly 3 times using tap water, mashed using a blender with the addition of twice amount of water, and filtered using a 200-mesh sieve. The starchy solution was deposited for 6 hours, and the precipitate was dried in an oven dryer at 50 C for 6 hours. The dried starch was crushed using a mortar, sieved using a 60 mesh sieve, and stored in a plastic clip at room temperature.
Bioplastics Preparation (Ulyarti et al., 2021) Yam’s starch (7.5 g) was poured into a beaker glass containing 233.75 g of distilled water, then stirred for 10 minutes without heating. The starch solution was then heated and stirred using a hot plate and magnetic stirrer for 30 minutes at 80 C.
After 10 minutes of heating, 3 g glycerol was added. At the 20th minute, 2.25 g clove oil was added. The heating process was continued for a total of 30 minutes. The paste (220 g) was then poured into a glass mould and dried in an oven at 50 C for 24 hours.
Pempek’s Preparation (Pratama et al., 2016) 500 g fish mince, 333 g tapioca, 30 g salt, and 11 g garlic were mixed until homogenized. About 20 g of the dough was shaped into cylinder of 5-6 cm length and 2 cm diameter. The shaped dough was placed in boiled water until floated in the water. Pempek was removed, drained and stored in a sterile plastic container to avoid bacterial contamination.
Total Staphylococcus aureus (SNI 2332.9:2011)
The number of Staphylococcus aureus in pempek was determined by dissolving the sample solids into saline solution (NaCl
79 0.9%) with a ratio sampel to saline solution 1:9. The sample was further homogenized.
1 ml of the sampel solution was diluted into concentration 10-1 to 10-7. 1 ml of the diluted sampel solution was inoculated into selective media Baird Parker Agar (BPA) and incubated for 48 hours at 37 C. The number of Staphylococcus aureus in colony forming units per gram sampel (cfu/g) was calculated using Formula 1.
S. aureus (cfu/g) = Number of colonies x Dilution factor ... (1) pH Value
Changes in pH of pempek under two difference packagings and storage times were measured by dissolving mashed pempek in distilled water with ratio of 1:2 (15 g pempek : 30 ml distilled water).
Samples in liquid form are measured by immersing a pH meter to determine the pH value of the sample.
Sensory Test (SNI 2346: 2015)
The sensory properties of pempek packaged in both bioplastics and polyethylene plastic were determined using 5 trained panelists. The sensory properties
to be tested included color, texture, and aroma attributes. A scoring test was performed using 5 scales.
The scale for color:
(1) Extremely dislike, (2) Dislike, (3) Somewhat like, (4) Like, (5) Extremely like.
The scale for texture:
(1) Very not chewy, (2) Not chewy, (3) Slightly chewy, (4) Chewy, (5) Very chewy.
The scale for Smell of Damage:
(1) Very bad, (2) Bad, (3) Slightly bad, (4) Not bad, (5) Not bad et al.
The scale for Aroma of clove oil:
(1) Not very typical of clove, (2) Not typical of clove, (3) Slightly typical of clove (4) Typical of clove, (5) Very typical of clove.
RESULT AND DISCUSSION The Number of Staphylococcus aureus
Pempek made out of mackerel fish contains high protein, therefore easily be damaged by Staphylococcus aureus bacteria.
The number of Staphylococcus aureus that grew in the pempek samples during storage can be seen in Figure 1.
Figure 1. The Number of Staphylococcus aureus in Pempek During Storage The increase in the number of
Staphylococcus aureus bacteria in pempek packed using PE plastics was started after 8
hours of storage. The logarithmic (exponential) phase started after 16 hours of storage and lasted after 48 hours. In 0
1 2 3 4 5 6 7 8 9 10
0 8 16 24 32 40 48
Storage (Hours)
Polyethylene Bioplastics Log Bacterialcounts (CFU/g)
80 contrast, pempek packed using bioplastics showed a slower growth of Staphylococcus aureus bacteria. The logarithmic (exponential) phase was not detected up to 48 hours of storage (Figure 1). Ulyarti et al.
(2021) reported that clove oil can inhibit pathogenic bacteria Staphylococcus aureus.
Clove oil causes morphological damage and leakage of intracellular component.
The clove oil inhibits the respiratory metabolism by inhibiting the citric acid pathway (Shi et al., 2020).
The slower growth of Staphylococcus aureus might be due to the presence of antibacterial compounds from clove oil, such as flavonoids, tannins, alkaloids, and eugenol. The flavonoid compounds induce cell wall hydrolysis and inhibit the synthesis of cell wall (Weng et al., 2023).
Apart from the flavonoid compounds, other compounds contained in clove flower oil such as tannins, alkaloids, and eugenol may inhibit the growth of Staphylococcus aureus bacteria. Tannin, however, inhibits biofilm development by Staphylococcus aureus without affecting its growth (Payne et al., 2013). Alkaloid can damage bacterial membrane and induce cell lysis (Herrera et al., 2022). The largest component of the antibacterial substance in clove flower oil is eugenol. The eugenol decreases the biofilm gene expression leading to eradicated biofilm and loss of protection to the bacteria (El-Far et al., 2021).
pH During Storage
Staphylococcus aureus can grow at 15 to 45 C and at up to 15% NaCl (Missiakas and Schneewind, 2013). Primary et al. (2016) stated that pempek damage can be seen from changes in texture, the formation of mucus and a decrease in pH. Both Pempek packaged using bioplastics and polyethylene plastic and stored at room temperature for 48 hours experienced a decrease in pH (Figure 2).
The decrease in pH value of pempek packaged using polyethylene plastic was in line with the increase in the number of Staphylococcus aureus bacteria in pempek during storage. The decrease of pH might be due to the microbial activity which degrades protein into amino acids (Karneta et al., 2013) or degradation of starch into glucose and further into acids.
Similar to that, the decrease in pH value of pempek packaged using bioplastics was also observed. The decrease in the pH value of pempek was also in line with the increase in the number of Staphylococcus aureus bacteria in pempek, and that the decrease was more moderate as the smaller number of bacteria would produces less acid (Figure 2).
Figure 2. The pH of Pempek During Storage 5.9
6 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8
0 8 16 24 32 40 48
pH
Storage (hours)
Bioplastics Polyethylene
81 Sensory Properties
The use of different packaging during storage had no significant effect on the color of pempek. Pempek stored using both bioplastics packaging and polyethylene packaging experienced a decrease in color during storage. Pempek color reduction from different packaging treatments is influenced by different factors. The decrease in the color of pempek packaged in bioplastics can occur due to oxidation of pempek fat during storage. Fat oxidation during storage may occur due to the high value of the oxygen transmission rate of bioplastics packaging.
The color degradation of pempek packed using PE plastics may occurred due to the bacterial activity. The absence of antimicrobial compounds and high humidity in pempek favours the bacterial activity. Food that contains meat or fish will turn a paler color when contaminated with Staphylococcus aureus (Arini, 2017; Hudson, 2022). The protein responsible for the meat pigment may undergo decomposition. The activity of proteolytic bacteria caused the fish meat becomes denatured and the color of the fish meat becomes pale white during storage (Fajri and Dasir, 2017).
Texture changes in pempek occurred in both packaging. Pempek packaged in polyethylene plastic underwent changes in texture due to the activity of the Staphylococcus aureus bacteria which cause the texture to become softer and slimier (Arini, 2017). The decrease in texture during storage is also caused by the changes in the water, fat, and protein
content in pempek (Karneta et al., 2013).
The texture of pempek which is packaged using bioplastics changed from chewy to hard. The change in pempek texture was due to the high water vapor transmission rate (WVTR) of the bioplastics. Yam starch bioplastic with addition of 1.5% clove oil has WVTR 21.32 g/m2.day (Ulyarti et al., 2021). This value is in class 2 (WVTR > 20 to 100 g/m2.day) according to the Japanesse Industrial Standard (Japanese Indusrial Standard, 2019). Therefore the bioplastics packaging was unable to prevent water loss from pempek during storage and produce hard surface in pempek.
Smell of Damage
The application of bioplastics and polyethylene plastic packaging in pempek did not significantly affect the aroma until it is stored for 48 hours. The average value of aroma damage of pempek can be seen in Table 1. Pempek packaged in polyethylene plastic also experienced a decrease in aroma during storage. The cause of the decrease in the aroma of pempek is due to bacterial activity. Karneta et al. (2013) reported that the rotten smell of pempek was caused by microbial activity which degraded protein into hydrogen sulfide, nitrogen oxides, and sulfur dioxide.
However, the aroma of pempek packaged in bioplastics during storage, did not show a rotten aroma during 48 hours of storage.
This is presumably due to the content of antibacterial compounds from clove oil which is able to inhibit damage to pempek during storage (Li et al., 2022).
Table. 1. The average value of color, texture, smell of damage and aroma of clove oil in pempek packaged with bioplastics and polyethylene plastic during storage
Storage
(hour) Color Texture Smell of damage Aroma of Clove Oil Bioplastics PE Bioplastics PE Bioplastics PE Bioplastics PE
0 4,0 4,4 4,0 4,2 4,6 4,4 4,4 -
8 4,0 3,8 3,8 3,8 4,4 3,6 3,0 -
16 3,8 4,0 3,6 3,8 4 3,6 2,6 -
24 3,2 3,4 2,8 3,2 3,8 3,2 2,4 -
48 2,8 2,4 2,2 2,0 4,0 1,2 2,0 -
82 Aroma of Clove Oil
The use of bioplastics packaging during storage showed that bioplastics packaging had no significant effect on the aroma of pempek produced, which can be seen in Table 1. Storage duration affects the distinctive aroma of cloves in pempek packaged using bioplastics. At 0 hours, the aroma of clove oil was undetected. At 8 hours of storage clove oil aroma starts to be detected. At 16 hours and 24 hours of storage the distinctive aroma of cloves begins to be noticed in pempek. The eugenol compounds which are volatile might be responsible for this.
CONCLUSION
Bioplastics from yam starch and clove oil can inhibit the growth of Staphylococcus aureus bacteria in pempek.
The decrease in pempek pH was in line with the increase in the number of Staphylococcus aureus in pempek which was stored for 48 hours. The pempek stored in bioplastics and polyethylene packaging both experienced similar changes in color and texture during the 48 hours of storage.
However, pempek packaged in bioplastics did not spoil after 48 hours of storage although preserved a clove oil aroma. In contrast, pempek packaged in polyethylene plastic has a very rotten aroma after 48 hours of storage. Bioplastics packaging from yam starch and clove oil can be used to prevent damage by Staphylococcus aureus bacteria in pempek during storage.
However, need improvement in bioplastics quality in order to be able to prevent color and texture damage.
ACKNOWLEDGMENT
Thanks to LPPM University of Jambi for the research grant under the scheme
“Penelitian Terapan”.
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