For vendors and consumers, keeping food items in peak condition is essential for enjoyment and safety. Preservation of products that require refrigeration can be particularly challenging, especially where chilling facilities are not consistently available. A food-borne illness, scombroid food poisoning, can result from consuming spoiled fish. It is believed that histamine, an agent also involved in allergic reactions, forms in the flesh as it decays. Consumption of histamines produces a variety of symptoms from rash and itching through to diarrhoea and vomiting depending on the sensitivity of the individual. A recent study in the Journal of Food and Drug Analysis looked at the effects of packaging type on fish product quality in a variety of storage conditions.
Milkfish was chosen for the study as it, along with tuna, mackerel and bonito, is often associated with scombroid poisoning due to the naturally high levels of histamine in the flesh. It is also widely aquacultured in the Indo-Pacific region making it economically important and consequently a popular food choice due to its abundance and reasonable price.
The researchers investigated the effects of polyethylene packaging (PEP) in air versus vacuum packaging (VP) on aerobic bacterial count, histamine formation, and total volatile basic nitrogen (TVBN) as measures of deterioration under the controlled storage temperatures of – 20 °C, 4 °C, 15 °C, and 25 °C. Regular samples were taken during the study period and homogenised. The pH was measured and bacterial colonies cultured on nutrient agar plates. Histamine content was determined by liquid chromatography and the TVBN was measured by the method of Conway’s dish for triplicate determinations.
The results showed that following storage for 8 weeks at -20 °C, there was no product degradation in either packaging type. Following storage at 25 °C, degradation and accumulation of hazardous levels of histamines rapidly occurred in both packaging types, exceeding the US Food and Drug Administration limits in less than a day. However, at both 4°C and 15°C, degradation occurred more slowly in VP. This observation has been attributed to the exclusion of oxygen in VP inhibiting growth of aerobic bacteria associated with food spoilage.
These findings highlight the benefits of VP of food products where temperatures may fluctuate from refrigerated for short periods of time, such as transporting food home from the shops or during haulage and stocking. However, they also underline the rapidity with which fish products may become toxic if stored incorrectly.
Breakages in the cold chain are a key consideration for food producers, packagers, hauliers and vendors and this study accentuates the importance of maintaining continuity and making appropriate packaging choices.
Kung HF, Lee YC, Lin CW, Huang YR, Cheng CA, Lin CM, Tsai YH. The effect of vacuum packaging on histamine changes of milkfish sticks at various storage temperatures. J Food Drug Anal. 2017 Oct;25(4):812-818. doi: 10.1016/j.jfda.2016.12.009. Epub 2017 Feb 14. PubMed PMID: 28987357.