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Abstract. Koesoemawardani D. Afifah LU, Herdiana N, Suharyo AS, Fadhallah EG, Ali M. 2021. Microbiological, physical, and chemical properties of joruk (fermented fish product) with different levels of salt concentration. Biodiversitas 22: 132-136. Joruk is a fermented fish product originated in Ogan Komering Ulu Timur, South Sumatra, Indonesia. The aim of this study was to determine the effect of salt on the microbiological, physical and chemical properties of joruk. This research was arranged in a Randomized Complete Block Design (RCBD), with treatment of salt concentrations at 5%, 10%, 15%, 20%, 25%, and 30% (w/w). The follow-up test used the Least Significance Difference (LSD) at 5%. The result of this study showed that the addition of 10% salt produced the best joruk with the best microbiological and chemical properties as follows: total LAB of 8.75 log cfu/g, total microbes of 13.25 log cfu/g, and total mold of 4.27 log cfu/g, pH of 5.85, total lactic acid of 2.97%, Total Volatile Base (TVB) of 153.05 mgN /100g, and water content of 59.33%. Based on this study, it is concluded that the addition of salt at different concentrations significantly affects the pH, total lactic acid, total lactic acid bacteria (LAB), and water content of joruk.

Phase changes of carbon dioxide (supercritical or subcritical) depend on its proximity to a pressure of 7.35 MPa and temperature of 31.1°C. Carbon dioxide becomes supercritical and subcritical when it is above and slightly below its critical point, respectively. This study aims to determine the effect of high-pressure CO2 treatments at a pressure of 900 psi, 950 psi (subcritical), and 1100 psi (supercritical) and at holding times of 5, 10, and 15 min on the quality parameters of white shrimp (Litopenaeus vannamei) and to determine the shelf life of white shrimp processed with the best treatment. The results showed that the interaction between pressure and holding time had a significant p < 0.05 effect on cholesterol, protein, moisture content, and b ∗ value, but pressure had a significant effect on carotene content. The best treatment was a supercritical CO2 treatment at 1100 psi for 10 min, which was determined based on a significant reduction in the number of microorganisms and no significant changes in color, texture, and fat content were observed compared with control. The best treatment was applied to process shrimps, which were then stored at 4°C to evaluate the effectiveness of scCO2 treatment on the shelf life. No significant changes were found in PV and lipid in treated and scCO2-treated shrimps during storage, but the treatment significantly affected pH, TVBN, and microbial counts. Among the samples, there was no hedonic difference in all sensory attributes. Supercritical CO2 treatment at 1100 psi for 10 min can be an alternative method for preservation of shrimps.

Microwave absorbent packaging materials currently tend to biomaterial. Chitosan is a dielectric biomaterial with polycationic properties. The aim of this study was to analyze characteristics of microwave absorbing packaging material made from composite chitosan-polyvinyl alcohol (PVA) polymer. The ability of the packaging material to absorb microwave was determined by reflection loss measurement. Formed packaging prototype resembles as a thin transparent yellowish plastic with thickness (0.11-0.22 mm) and the tensile strength (106.33±2.82-143.00±2.59 kPa). SEM analysis showed homogenous structure characterized by interaction between chitosan and PVA. Optimum absorption value was obtained from chitosan concentration of 1%, with average value of reflection loss was (-31.9289±4.0094) dB.<br />Keywords: chitosan, material packaging, microwave, reflection loss

Plastic waste continues to increase every year along with the increasing number of industries and population. Accumulated plastic waste has a negative impact and harm the environmental. The initiative of 3R (reduce, reuse, and recycle) has been widely promoted, but it is not optimally implemented. The use of organic materials to substitute the synthetic materials in plastic become alternative to prevent this problem continues in the future. Bioplastics are naturally decomposed by the soil and made from renewable materials. This review aims to explore the potency of cassava peels (Manihot esculenta) and seaweed carrageenan (Eucheuma cottonii) as the bioplastic material. The method used is an effective literature review and in accordance with the topic being discussed. The discussion method is carried out based on research results that have been found by previous researchers, which are then integrated with other researchers to get strong results and conclusions. Cassava peel waste and seaweed carrageenan have the potency to be made into bioplastics because they contain polysaccharide that can form a thin layer films based on gelatinization. The development of cassava peel waste and seaweed carrageenan will becoming the promising materials as substitutions for synthetic plastic, and also could help prevent the negative impact of plastic waste. Furthermore, since the cassava and seaweed are naturally abundant, it will promoting the environmental sustainability.