# Effects of Temperature, Light and Digestive Fluid on the Stability of Major Arsenic Species in Antarctic Krill (Euphausia superba)

## TL;DR

This study examines how storage and digestion affect arsenic stability in Antarctic krill, finding that refrigeration preserves arsenobetaine while digestion reduces toxic forms.

## Contribution

The study reveals how storage and digestion transform arsenic species in krill, offering new insights for food safety guidelines.

## Key findings

- Arsenobetaine remains stable under refrigeration but degrades with light exposure or room temperature storage.
- Simulated digestion reduces toxic As(III) and increases safe AsB, with new arsenic forms emerging during intestinal digestion.
- Proper storage and digestion processes lower overall arsenic toxicity in Antarctic krill.

## Abstract

This study focuses on how storage conditions (temperature, light) and human digestion affect the stability of arsenobetaine (AsB), the main arsenic form in Antarctic krill (Euphausia superba). Krill samples stored for different durations underwent freezing, refrigeration, and room temperature treatments, with some additionally exposed to light. Results showed AsB stayed stable under refrigeration or short-term storage but dropped significantly after light exposure. In simulated digestion tests, gastric treatment reduced the more harmful arsenic form As(III) while boosting safe AsB levels. During intestinal digestion, two new arsenic forms emerged, though overall toxicity decreased. These findings support safe krill storage, processing, and related food safety guidelines.

Antarctic krill, an important marine resource, contains significant arsenic levels, predominantly as the low-toxicity arsenobetaine (AsB). However, the stability of AsB during post-harvest storage and its transformations during human digestion are poorly understood, which is critical for a comprehensive safety assessment. This research investigated the effects of temperature, light exposure, and in vitro simulated digestion on the stability and transformation dynamics of major arsenic species in Antarctic krill. The results revealed that AsB predominated among the arsenic species. AsB remained stable during long-term frozen storage (−18 °C for 5 months) and short-term refrigeration (4 °C for 2 days). However, AsB content decreased significantly during storage at ambient temperature (25 °C) and after prolonged light exposure (>8 h), indicating that improper storage conditions can lead to its degradation. During simulated gastrointestinal digestion, a significant transformation of arsenic species was observed. The content of toxic inorganic As(III) decreased significantly during the gastric phase, while the less-toxic AsB content markedly increased. Furthermore, dimethylarsinic acid (DMA) and As(V) were newly detected during the intestinal phase. These findings demonstrate that arsenic stability in krill is highly dependent on storage conditions. Moreover, the transformations during digestion—notably the decrease in As(III) and increase in AsB—suggest a potential reduction in overall arsenic toxicity upon consumption. This provides a critical theoretical basis for developing storage guidelines and improving human health risk assessments for Antarctic krill products.