Key Factors Affecting the Flesh Flavor Quality and the Nutritional Value of Grass Carp in Four Culture Modes.

Junming Zhang,Ermeng Yu,Gen Kaneko,Jinhui Sun,Guangjun Wang,Yun Xia,Wangbao Gong,Zhifei Li,Jun Xie,Kai Zhang,Jingjing Tian

doi:10.3390/foods10092075

Abstract

Flavor and nutritional value are important qualities of freshwater fish products, but the key factors affecting these quality parameters remain unclear. In this study, four typical aquaculture modes, including the commercial feed treatment (control), faba bean treatment (FBT), grass powder treatment (GPT), and waving water treatment with commercial feed (WWT), were used to explore the regulatory effect of water quality and feed (eaten and uneaten) on the flesh flavor and nutrition in grass carp (Ctenopharyngodon idella), a freshwater fish of the largest global production. During the culture period (90 days), water quality parameters of the four modes were measured every 15 days, and the flavor quality was evaluated by volatile flavor compounds detection and electronic nose analyzer. Flesh crude protein, crude fat, free fatty acid and free amino acid profiles were also determined. The results showed that, in the late period, the FBT mode had the poorest water quality with highest concentrations of nitrite and nitrate, while the GPT mode has the best water quality among the four modes. Most flesh flavor compounds found in the flesh of the control, GPT and WWT modes were pleasant. In the FBT mode with the poorest water quality, on the other hand, we found lower flavor quality (higher contribution of fishy compounds), higher water content, and lower contents of crude protein, crude fat, free fatty acids and free amino acids, compared to the other three modes. Correlation analyses showed that nitrite and nitrate are probably key water quality factors affecting the flavor quality and nutritional values besides eaten feed and uneaten feed factors. This study can serve as an important reference for ecological regulation and feeding administration of flesh quality in freshwater aquaculture fish.

Highlights

Grass carp (Ctenopharyngodon idella), with the highest global production in freshwater species, has provided inexpensive and high-quality animal protein for consumers [1]
The upward trends of total ammonia nitrogen, total nitrogen, soluble reactive phosphorus and total phosphorus were consistent in the four culture modes, while the trends of nitrate and nitrite were different depending on the modes (Figure 1a,b)
The nitrite content in the faba bean treatment (FBT) mode increased to 1.08 mg/L at 90 d, while those in other three modes were 0.45 ± 0.039 mg/L, 0.15 ± 0.002 mg/L

Summary

Introduction

Grass carp (Ctenopharyngodon idella), with the highest global production in freshwater species, has provided inexpensive and high-quality animal protein for consumers [1]. In the case of freshwater fish products, consumers tend to prefer products with less flavor and high nutritional value. Improving flavor quality and nutritional value can effectively enhance the market value of grass carp. The number of attempts to improve the flavor quality and nutritional value of fish is in ascent. It has been reported that dietary plant protein and oil sources significantly reduce the contents of the volatiles and improve the nutritional value in fillets of gilthead sea bream [5]. Further exploration of key water quality factors affecting the flavor quality together with nutritional value will be of great significance for the improvement of freshwater fish quality

Methods

Results

Conclusion