The objective of this study was to develop protein bioplastics from fish waste using different types of plasticizers; polyethylene glycol, triethylene glycol and glycerol. Fish protein powders (head, skin, scales, viscera) were prepared from sardine byproduct (SBP), mackerel fillet powder (MFP) and mackerel byproduct powder (MBP). Protein content was characterized using proximate analysis and amino acids was determine using amino acid analysis. SBP was transform into bioplastics by using extrusion and compression moulding. The properties were characterized using thermo gravimetric analysis (TGA) and mechanical testing. Protein content in byproduct (SBP and MBP) were reasonable at approximately 40-60%. TGA result showed two stages of thermal decomposition starting at 230 °C. Below 230 °C, it was believed that protein denaturation occurred, involve structural or conformational changes from native structure without alteration of amino acid sequence. Further heating after 230 °C showed massive weight loss that lead to degradation. Mechanical properties was majorly influenced by plasticizers which improved the elongation at break properties. Glycerol was found to be the most effective plasticizer among those studied here, possibly because of its characteristics such as low molecular weight, high solubility in water, and large protein miscibility. The results obtained in this study showed that plasticizer types and concentration significantly improve film properties and enhances their suitability for single used of agriculture applications.

In this study, halochromic sensor-based poly (lactic acid) (PLA) and polyethylene glycol (PEG) film as real-time sensing is successfully fabricated. Bromocresol purple (BCP) dye concentrations were varied (0.01 and 0.03 wt%/vol) in halochromic PLA/PEG film that changed its color from yellow to purple at a basic environment. The efficacy of the film with more BCP loading toward basic sensing was significant, where the material showed distinct color change with rapid response time. The color changes were proven by the CIE lab analysis, which showed that the initial and final colors of the indicator after interaction with PLA/PEG film are well above the limit for visual perception. The film response in base vapor was further determined by the amount of total volatile basic nitrogen (TVB-N) released from mackerel. The mackerel was kept at room temperature (26 ± 1 C) for 24 h and chiller temperature (3 ± 1 C) for 11 days. The threshold of food spoilage indicated by the TVB-N and the ΔE was reached at 18 h at room temperature when it started to deteriorate on Day 7 in the chiller. The findings suggest that a pH-sensor made of the PLA/PEG/BCP films is suitable for multiple applications, particularly in base solution and vapor sensing detection.

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