Biochemical and physicochemical properties of shrimp (Pandalus borealis) compounds after compact filter press process

Background

Most of the shrimp side streams are discarded due to the lack of appropriate processing techniques/methodology for their utilization, which is not only a loss of potentially valuable compounds, but also leads to environmental pollution. The study aimed to employ a mechanical filter press to separate the liquid called press juice (PJ) and the solid named press cake (PC) fraction from shrimp head and shell (H&S).

Results

The proximate composition was performed, including amino acids analysis, protein content, fatty acids, and the main volatile compounds. In the whole shrimp (WS), the average values of protein, lipid, dry matter, and ash content were recorded at 14.7%, 2.9%, 21.1%, and 4.8%, respectively. The protein percentage reached 10.1% in H&S, indicating considerable amount of protein leftover in the shrimp side streams (p < 0.05). The major PUFAs in WSs' sample were Eicosapentaenoic acid (EPA) (8.8%) and Docosahexaenoic acid (DHA) (7.8%). Furthermore, the values of EPA and DHA a showed nearly two-folded increase after peeling and filter-pressing, PC sample. Total amino acids in the WS, H&S, PJ, and PC samples were found to be 94.6, 67.7, 22.2, and 76.6 mg/g, respectively. From the nutritional point of view, non-essential amino acids represented higher values (13.2%–56.9%) compared to essential amino acids (9.0%–37.6%). The major components of 5′-neucleoitides in WS sample were in order of guanosine-5′-diphosphate (GDP) ≫ hypoxanthine (HYP) > inosine-5′-monophosphate (IMP) ≫ adenosine-5′-monophosphate (AMP) > adenosine-5′-diphosphate (ADP) with values of 684.4, 293.6, 201.4, 25.6 and 16.2 μg/g sample, while no inosine (INO), guanosine-5′-monophosphate (GMP), and guanosine-5′-triphosphate (GTP) were detected. Equivalent umami concentration (g MSC/100 g) was recorded as 0.63, 0.07 for WS and H&S samples and 0.015 for PJ sample, which indicates a significant drop from the shrimp raw material toward the side streams. Most volatile compounds belonged to alkenes followed by alkanes groups.

Conclusion

This work showed the possibility to employ the filter press machine to obtain PJ and PC from shrimp H&S, after peeling processing. The fractions present an interesting nutritional composition and value.