Anthocyanins from Agro-waste as Time-Temperature Indicator to Monitor Freshness of Fish Products

Fish products perish easily due to microbial contamination. Uncontrolled thawing will increase the rate of microbial activity at every 10°C increase in temperature. One of indicator that can detect food quality is the timetemperature indicator (TTI) with changes in pH. However, these indicators are generally made of synthetic chemicals which tend to pollute the environment. This study aimed to summarize various studies on anthocyanins from agro-waste as time-temperature indicator to monitor freshness of fish products. This research used systematic literature review (SLR) from various relevant research and resources. The SLR process includes practical screening, quality appraisal, synthesizing, and reviewing. Anthocyanins derived from agro-waste than can be developed into TTI are purple yam peel, black plums peel, blueberries peel, rambutan peel, sweet potato peel, dragon fruit peel. The TTI from agrowaste anthocyanins can be developed to monitor freshness of fish products. Article History: Received 10 Apr 2021 Revised 29 Apr 2021 Accepted 16 May 2021 Available online 17 May 2021 ____________________ Keyword: Agro-waste, Fish Products, Time-Temperature Indicator, Anthocyanins Indonesian Journal of Educational Research and Technology Journal homepage: http://ejournal.upi.edu/index.php/AJSE/ Indonesian Journal of Educational Research and Technology 1 (2) (2021) 67-72 © 2021 Universitas Pendidikan Indonesia


A B S T R A C T S A R T I C L E I N F O
Fish products perish easily due to microbial contamination. Uncontrolled thawing will increase the rate of microbial activity at every 10°C increase in temperature. One of indicator that can detect food quality is the timetemperature indicator (TTI) with changes in pH. However, these indicators are generally made of synthetic chemicals which tend to pollute the environment. This study aimed to summarize various studies on anthocyanins from agro-waste as time-temperature indicator to monitor freshness of fish products. This research used systematic literature review (SLR) from various relevant research and resources. The SLR process includes practical screening, quality appraisal, synthesizing, and reviewing. Anthocyanins derived from agro-waste than can be developed into TTI are purple yam peel, black plums peel, blueberries peel, rambutan peel, sweet potato peel, dragon fruit peel. The TTI from agrowaste anthocyanins can be developed to monitor freshness of fish products.

INTRODUCTION
Fish products perish easily due to microbial contamination (Rawat, 2016). About 6-10% of the world's total fish production is inedible due to rot during improper storage and distribution processes (Arvanitoyannis and Kassaveti, 2008). Uncontrolled thawing will increase the rate of microbial activity at every 10°C increase in temperature (Roiha et al., 2018). Spoilage bacteria degrade fish protein into alkaline compounds which increase the acidity (pH) of fish, making it inedible (Omafuvbe et al., 2000). Therefore, it is necessary to conduct a study to maintain quality of fish products by developing indicators.
One indicator that can detect food quality is the temperature time indicator or TTI with changes in pH (Zhai et al., 2018;Shi et al., 2021a;Shi et al., 2021b). Fish protein decomposition in fish will release volatile compounds such as trimethylamine which is reactive to natural pH indicators (Kang et al., 2018). The main principle of acid-based TTI is to detect changes in pH by displaying a gradual color change because of an irreversible chemical reaction (Bobelyn et al., 2006). However, these indicators are generally made of synthetic chemicals which tend to pollute the environment (Syahirah et al., 2018).
Current research has proven that natural anthocyanin pigments can be used as pH indicators since their sensitivity to pH changes that lead to color changes (Pakolpakçıl et al., 2021). However, the anthocyanins used usually come from staple foods such as sweet potatoes, dragon fruit, and red cabbage. Therefore, this study aimed to summarize various studies on anthocyanins from agro-waste as time-temperature indicator to monitor freshness of fish products.

Figure 1. Method and process of SLR used.
This research used systematic literature review (SLR) from various relevant research and resources. The SLR process includes practical screening, quality appraisal, synthesizing, and reviewing (Peffers et al., 2007). Figure 1 describing the method of collecting data research from google scholar.

ANTOCYANINS FROM AGRO-WASTE
Anthocyanins are naturally found in plants, fruits, and vegetables in the form of watersoluble pigments (Arruda et al., 2021). Anthocyanins consist of several conjugated phenolic rings. When the pH changes, the protonation and deprotonation of the hydroxyl groups along the phenolic rings of the anthocyanin molecule change the conjugation pattern across the molecule causing the color change (Khoo et al., 2017). In general, anthocyanins can give a blue, red, or purple color. Therefore, anthocyanins may also be found in parts that are not eaten, such as fruit skins.

ANTHOCYANINS FROM AGRO-WASTE AS TIME-TEMPERATURE INDICATORS TO MONITOR FRESHNESS OF FISH PRODUCT
Fish products potentially contaminated at temperatures above 10°C by the bacteria Vibrio Parahaemolyticus, Escherichia coli, Aeromonas, Salmonella, Staphylococcus, Clostridium botulinum, and others (Novotny et al., 2004). Damage to fish is characterized by the formation of trimethylamine (TMA) from the reduction of trimethylamine oxide (TMAO). The breakdown of protein by bacteria will release volatile compounds such as trimethylamine. pH <7.6 indicates fresh quality, pH 7.6 -7.9 indicates edible but not number one quality, and pH> 7.9 indicates rotten value.
By knowing these parameters, anthocyanins can act as a Time-Temperature Indicator to detect changes in pH by displaying a gradual color change because of an irreversible chemical reaction (Bobelyn et al., 2006). Table 1 summarizes some agricultural limes that contain anthocyanins and have the potential to be used as indicators of fish freshness.

CONCLUSION
Time-Temperature Indicator (TTI) can be made from agro-waste anthocyanins. Agro-waste than can be developed into TTI are purple yam peel, black plums peel, blueberries peel, rambutan peel, sweet potato peel, dragon fruit peel. The TTI from agro-waste anthocyanins can be developed to monitor freshness of fish products.

ACKNOWLEDGEMENTS
Highest appreciation to The Study Program of Agro-Industrial Education and The Faculty of Technical and Vocational Education, Universitas Pendidikan Indonesia for facilitating and sponsoring this research.

AUTHORS' NOTE
The authors declare that there is no conflict of interest regarding the publication of this article. Authors confirmed that the paper was free of plagiarism.