# A Comparative Study of the Fatty Acid Profile of Non-Edible and Edible Tissues of Raw and Processed Common Octopus (Octopus vulgaris)

## TL;DR

This study compares the fatty acid content in edible and non-edible parts of octopus, finding that non-edible parts still have valuable nutrients.

## Contribution

The study reveals that octopus viscera, typically discarded, contains significant nutritional and industrial value.

## Key findings

- Non-edible tissues (viscera) had lower ω3-PUFA and higher eicosapentaenoic acid than edible tissues.
- Cooking and freezing reduced PUFA and ω3-PUFA content while increasing saturated fats.
- Octopus viscera can be a valuable resource for food and pharmaceutical industries.

## Abstract

A comparative study of the fatty acid (FA) composition of non-edible (viscera) and edible (mantle and arm) tissues of octopus (Octopus vulgaris) was carried out. According to the specimen size, three different groups (1–2 kg, 2–3 kg, and 3–4 kg, respectively) were taken into account. The effect of the cooking process (40 min at 90 °C) and frozen storage (4 months at −18 °C) was analyzed. In all kinds of samples, the polyunsaturated FA (PUFA) group was the most abundant (p < 0.05) and monounsaturated FAs were the least abundant (p < 0.05). Lower (p < 0.05) ω3-PUFA, ω3/ω6 ratio and docosahexaenoic acid values were detected in viscera (35.4–41.9%, 3.0–4.5%, and 12.7–17.5%, respectively) than in edible tissues (44.4–52.5%, 4.1–6.1%, and 24.3–30.1%, respectively). Conversely, higher (p < 0.05) eicosapentaenoic acid content was detected in viscera (19.6–21.9%) than in the edible tissues (17.2–19.3%). In most cases, the cooking process and frozen storage led to an average decrease in the PUFA and ω3-PUFA content and to an increase in the saturated FA presence. In agreement with current nutritional recommendations, all tissues showed great levels of highly valuable indices regarding the lipid fraction. The study proves that viscera, a waste substrate, can be considered a relevant source for food and pharmaceutical industrial requirements.