Honey is produced from flower nectar (honey flower) or secretions from plants and or insect excretions. Bees collect these sweet substances, enrich them with their own substances and store them in beehives. Honey contains 38% fructose sugar, 31% glucose, 10% other types of sugar, 18% water and 3% other ingredients. Honey is rich in organic acids such as gluconic acid, acetic acid, lactic acid, citric acid, succinic acid and formic acid. The acid is the action result of enzymes such as glucose oxidase in the sugar contained in honey and is arranged on average 0.5% of the weight of honey. Organic acids found in honey are believed to contribute to organoleptic properties such as the taste and color of honey.
One of the processed fishery products liked by the community is pressure-cooked milkfish. Pressure-cooked milkfish is one type of processed fish product with advantages, their bones from caudal to chepal are so soft that all parts of the body can be consumed. It has a high protein and water content equal to 27.1% and 60.93%, so it is easy to go off at room temperature storage. The short shelf life of fish products is caused by bacteria that remain and recontamination after the process. The maximum limit of microorganisms contained in food products is 5.0 x 10 5 colonies / gram (National Standardization Agency, 2009).
Some researchers have proven that honey has the ability to inhibit the growth of microorganisms and bacteria spoiling food and causing foodborne disease. Various damage and food poisoning caused by microorganisms can be prevented by preservation techniques to prevent or slow the growth of microbes. Honey has also been shown to have antibacterial activity against Staphylococcus aureus, Escherichia coli and Salmonella sp. The antibacterial compounds in honey have been considered to be a natural preservative for processed products. Honey is expected to improve the quality and shelf life of pressure-cooked milkfish.
The natural preservative, chitosan, has been studied and proven to be able to preserve fish for 72 hours, and the liquid smoke of coconut shell is proven to be able to preserve milkfish for 72 hours. The use of natural preservatives for food products is considered safer for consumption compared to chemical preservatives that can cause poisoning due to excessive use and unregulated doses. We conducted this research to find out how the effect of pressure-cooked milkfish soaking in honey on the total number of bacteria and organoleptic values during storage at room temperature.
Honey solution with various concentrations (20%, 25%, and 30%) is used as a preservative by soaking the pressure-cooked milkfish as a treatment. As a negative control is pressure-cooked milkfish without preservative and positive control is pressure-cooked milkfish soaked with 0.1% sodium benzoate solution commonly used as chemical preservative. Soaking is performed for 30 minutes and then put into oven for 30 minutes at a temperature of 50 ° C. The pressure-cooked milkfish stored at room temperature (20-25 oC). Total bacterial, organoleptic, pH and water content observations were carried out before storage (0 hours) and after 24 hours, 48 hours, 72 hours, and 96 hours of storage. Organoleptic value refers to SNI 4106.1-2009 by involving 30 panelists of untrained students. The nature of organoleptic testing is subjective because it only relies on the senses and sensitivity of the panelists.
Our results prove that honey with a concentration of 30 percent can preserve milkfish for up to 72 hours of storage at room temperature with a total bacterial 2.3 x 10 5 colonies / gram, less than the maximum limit of microbial contamination 5.0 x 10 5 colonies / gram. The ability of honey to preserve pressure-cooked milkfish is supported by hydrogen peroxide as antibacterial. Hydrogen peroxide is the result of the action of glucosidase secreted by the hypopharyngeal gland. Glucosidase breaks down bee glucose to form gluconic acid and hydrogen peroxide.
Honey with 30 percent concentration is also able to maintain product quality for 72 hours stored at room temperature. Even the average organoleptic value is at 7.45 according to SNI of fishery products, organoleptic value pressure-cooked milkfish preserved with honey was 30% higher than pressure-cooked milkfish preserved with 0.1% sodium benzoate solution.
The pH value of pressure-cooked milkfish soaked in honey solution tends to be acidic because honey is acidic. Honey has a pH that is low enough (3.2-4.5) to inhibit or prevent bacterial growth at pH 7.2-7.4. The water content of pressure-cooked milkfish preserved with 30% honey is the lowest compared to Presto milk preserved with honey concentrations of 20%, 25% and sodium benzoate solution 0.1%. The lower water content causes long shelf life of preserved milkfish preserved with 30% honey solution for up to 72 hours (three days) at room temperature, with microbial contamination less than 5.0 x 10 5 colonies / gram.
Author: Wahju Tjahjaningsih
Details of this research available at:
D A Hakim, W Tjahjaningsih and Sudarno. 2019. Antibacterial activity of honey in preserving high-pressure cooked milkfish stored at room temperature. IOP Conf. Ser.: Earth Environ. Sci.236 (2019) 012079.