Freshness Analysis of Color, NH₃, H₂S, and pH on Salmon Spoilage Using the PCA Method

Telkom University, Jl. DI Panjaitan No.128, Banyumas, Central Java, 53147, Indonesia

^* Corresponding author: erlinanurarifani@telkomuniversity.ac.id

Abstract

Consumer acceptance and food safety represent critical issues for wholesalers and retailers of fresh fish and seafood, particularly salmon, which has become an important component of the human diet. Salmon is highly valued due to its richness in protein and essential fatty acids, making it a popular and nutritious food source. The objective of this study is to develop and evaluate an innovative storage monitoring system for salmon that enables early detection of spoilage through the measurement of ammonia (NH₃) and hydrogen sulfide (H₂S) gases. Traditional spoilage detection methods are subjective and less sensitive, thus requiring real-time systems. This study integrates MQ-137 and MQ-136 sensors with a microcontroller for continuous monitoring of NH₃ and H₂S, with data recorded at five-minute intervals over a four-day period, an the data analyzed using PCA to interpret spoilage dynamics. The results demonstrate that the system successfully tracks NH₃ and H₂S gas emissions during the spoilage process, even when visual color changes in salmon remain subtle at the early stages. Kinetic modeling revealed that the release of H₂S and NH₃ follows zero-order reaction patterns, with rate constants of 0.92 and 0.84, respectively, indicating a strong correlation between storage time and spoilage level. These findings highlight the potential of the proposed monitoring system as an early-warning tool for salmon spoilage, ultimately improving food safety, extending shelf-life management, and supporting consumer trust in seafood products.