Proximate, minerals, carotenoid and trypsin inhibitor composition in the exoskeletons of seafood gastropods and their potentials for sustainable circular utilisation.

Periwinkle shells of Tympanotonus fuscatus, Pachymelania aurita, and Thais coronata were analyzed for their proximate composition, nutritionally significant minerals, trypsin inhibitors, and carotenoids. The mean values obtained were compared using an ANOVA test. The results showed that T. fuscatus had the highest mean moisture content of 0.96 ± 0.14% and a mean value of 0.49 ± 0.13% for crude fibre but was not significantly different (P > 0.05) from P. auritus. The crude protein and fibre content of T. fuscatus was significantly higher (P < 0.05) than other periwinkle samples. T. coronata had the highest mean total ash content and was significantly different (p < 0.05) from other periwinkle samples. T. fuscatus had the highest mean value for Mg (0.32 ± 0.03 mg/kg) and differed significantly (P < 0.05). The mean Ca content of P. aurita was not significantly different (P > 0.05) from that of T. coronata. The mean values of CaCO in T. fuscatus, P. aurita, and T. coronata were 57.20 ± 2.46, 59.50 ± 3.23, and 62.36 ± 1.56 (mg/kg), respectively. T. coronata was significantly different (P < 0.05) from other periwinkle samples. The mean values of carotenoids in T. fuscatus, P. aurita, and T. coronata were 7.17 ± 2.14, 18.00 ± 5.27, and 11.20 ± 3.60 (mg/kg), respectively, and P. aurita was significantly different (P < 0.05) from other periwinkle samples. T. fuscatus and P. aurita had shells with significant amounts of trypsin inhibitor (23.30 ± 4.50 mg/kg and 22.90 ± 14.10 mg/kg, respectively), making them less suitable for livestock feed. In contrast, T. coronata had a lower mean value of 11.80 ± 7.19 mg/kg for trypsin inhibitor, making it an excellent addition to livestock feed. The low crude fibre and fat contents of the periwinkle samples in this study make them suitable for processing complementary foods, especially for hypertensive patients. The high percentage of CaCO in periwinkle shells makes them a probable source used in the production of slurry for chromatography. The findings suggest that periwinkle shells contain specific minerals that can be applied in numerous industries. Increased use of these gastropod shells will result in successful application in product creation and a sustainable bio-circular economy.