This study explores the viability of insect meal as an economical and sustainable raw material for fish feed. Utilizing Anton Paar Brabender Instruments, the research focuses on optimizing feed composition through rheological analysis. The methodology includes moisture determination and gelatinization property analysis, enhancing insights into fish feed digestibility.

INTRODUCTION

In light of the escalating expenses and ecological repercussions associated with fish meal production, the utilization of insect meal emerges as a promising alternative for the cost-effective generation of raw materials in the manufacturing of fish feed (1). This potential transition is underscored by the remarkable attributes of insect meal, including its elevated protein content and biological valence, which are pivotal elements in the development of sustainable feed formulations (2). The Anton Paar Brabender Instruments, through its innovative technologies, offers a feasible solution for the exploration and optimization of fish feed production on a smaller laboratory scale. This entails not only the meticulous analysis of rheological properties in the final product but also provides a platform for refining the composition of raw materials and enhancing manufacturing processes. In essence, the integration of the Anton Paar Brabender Instruments into the production workflow facilitates a comprehensive approach towards achieving both economic viability and environmental sustainability in the evolving landscape of fish feed manufacturing.

Figure 1: Screw configuration KETSE 20/40

Table 1: Process conditions - KETSE 20/40

EXPERIMENTAL

1. Material – Fish Feeding Manufacturing

Three batches of fish feed were produced in the form of pellets by use of Brabender twin screw extruder KETSE 20/40 (see Table 1 and Figure 1). For manufacturing the contained fish meal was replaced with no-fat black soldier fly (Hermetia illucens) larvae meal in concentrations of 0, 50 and 100 % (see Figure 2).

Figure 2: Extruded fish feed (whole and ground)

2. Method

The investigation into the digestibility of fish feeds, specifically in relation to their gelatinization properties, was conducted through a systematic approach involving key procedures.

The initial step involved the determination of moisture content in the pellets. This was carried out using the MT-CA method, a reliable technique known for its precision in moisture analysis.

Following the moisture determination, the extrudate underwent a grinding process utilizing the Break Mill SM4. This crucial step aimed to achieve a consistent and homogenous particle size, preparing the samples for subsequent analysis.

The gelatinization properties of the flours were then comprehensively examined using the MVAG (Figure 3). This analytical tool facilitated a thorough exploration of key characteristics associated with gelatinization, providing valuable insights into the thermal transitions and behavior of the feed components.

Figure 3: MVAG Measurements

These procedures were systematically executed to unravel the intricate relationship between fish feed digestibility and its gelatinization properties. The selected methods were chosen for their precision and reliability, ensuring accurate assessments and contributing to the overall robustness of the research findings.

RESULTS AND DISCUSSION

The results of the MVAG measurements (see Figure 3) have shown that a higher concentration of insect meal lowers the residual gelatinization of starch, which is directly related to the digestibility of fish (3).

Table 2: Amount of fish meal substituted by black soldier fly larvae meal

In consideration of the results of Table 2 it can be said, that through the use of insect meal ER and SME of the batches are increasing while BD, BF and DP are decreasing.

SUMMARY

Trials showed that insect meal can be used as fish meal substitution for fish feed manufacturing. It should be noted that there are significant influences concerning the extrusion process and that the change of the product properties has to be determined depending on the intended use of the feed.

With regard to further investigations, changing of process conditions e.g. variating the extruder screw speed might optimize the product properties as desired. Feeding trials are needed to evaluate the feed acceptance and the nutritional value of the product. Studies indicate that the nutritional value of black soldier fly larvae meal is lower than fish meal. Therefore, higher quantities may be required for a proper diet. Further research is needed in order to improve the omega-three fatty acid spectrum of the fish free product. The addition of micro algae with high omega-three contents might be a solution.

However, the extrusion process has to be adapted when fish meal is substituted by insect meal. Should black soldier fly larvae meal get cheaper than fish meal, it could prove to be a viable option to reduce the environmental impact of aquaculture in the future.