Comparative Analysis of Preservation Techniques on Nutritional Quality and Shelf Life of Shellfishes (Penaeus monodon and Farfantepenaeus notialis) in Nigeria

Abstract

Fresh tiger prawn (Penaeus monodon) and southern pink shrimp (Farfantepenaeus notialis) were collected from Igbokoda Market in Ondo State, Nigeria, and preserved using freezing (–15ºC), smoking (105–110ºC), oven drying (80ºC for 10 h), and salting (360 g/L brine). The study evaluated how these methods influenced nutrient quality by analyzing proximate composition, free fatty acid (FFA), and total volatile nitrogen (TVN) levels over eight weeks. Results revealed notable differences in nutrient retention across preservation techniques. In the first week, frozen shrimp showed the lowest protein levels (35.18 ± 1.97% for P. monodon and 45.06 ± 1.34% for F. notialis), whereas the oven‑dried samples recorded the highest values (74.86 ± 0.17% and 70.92 ± 1.19%, respectively. Moisture content was highest in frozen shrimp (46.18%) and lowest in oven-dried samples (5.38%), highlighting the role of dehydration in limiting spoilage. FFA levels increased progressively, indicating lipid oxidation, with oven-dried samples maintaining the lowest FFA and thus better oil stability. TVN values, a measure of protein degradation, also rose with storage duration, peaking in smoked samples, while frozen shrimp exhibited the lowest TVN levels. Among the preservation methods studied, oven drying proved most effective for maintaining protein quality, minimizing moisture uptake, and reducing spoilage, while freezing better preserved freshness in F. notialis. Smoking and salting were less effective due to higher TVN and FFA accumulation. These findings suggest oven drying as the most reliable preservation technique in resource-constrained settings, with potential to reduce post-harvest losses and enhance the commercial value of prawns.