Upcycling of whitefish side streams: Gentle processing improves sensory quality compared to traditional fishmeal processing

The upcycling of whitefish side streams into food-grade powders offers an opportunity to increase resource efficiency in the whitefish industry. This study compared a conventional fishmeal process based on presscake production with a gentle processing method involving washing of raw materials, mild steam cooking, and direct steam drying. Presscake-derived powders showed very high odour intensity and poor palatability, making them unsuitable for human consumption. Washing of cod heads and backbones with fresh (FW) or salt water (SW) effectively reduced pro-oxidative compounds (e.g., iron) and volatile nitrogen compounds, resulting in more consistent product quality. Colour measurements showed increased lightness (L∗) and reduced redness (a∗) and yellowness (b∗) after 2–3 wash cycles. Saltwater washing increased sodium content to 3.7 % after three cycles, corresponding to 1.5 g per 40 g powder. Sensory evaluation showed reduced odour and flavour intensity in gently processed powders compared with fishmeal, although washing alone resulted in limited additional sensory improvement. Overall, integrating washing with gentle steam processing produced lighter, milder, and more consistent powders, demonstrating strong potential for food applications and improved onboard utilization of whitefish side streams.