A novel source of food hydrocolloids from Trigonella elliptica seeds: extraction of mucilage and comprehensive characterization

Abstract

Background: In this study, the effects of seed weight (4, 8, and 12 g), extraction temperature (30, 60, and 90 °C), and pH (4, 7, and 10) on the yield of mucilage extraction from fenugreek seeds and its chemical properties were investigated using responsesurface methodology.Results: The optimum condition for mucilage extraction was a seed weight of 8.30 g, a temperature of 86.10 °C, and pH 6.90. The results showed that the dry weight of extracted mucilage increased with increase and decrease of extraction temperature and pH respectively at high seed weight. Increasing temperature and pH increased the extraction yield, and the effect was more considerable at low seed weight. The maximum carbohydrate content of mucilage was achieved at average levels of variables. The protein, flavonoid, and total phenolic contents of extracted mucilage increased with increasing temperature. Both flavonoid and total phenolic contents were maximum at neutral pH, but they were maximum at moderate and low levels of seed weight respectively. Maximum antioxidant activity was obtained at the highest extraction temperature, seed weight of 8 g, and neutral pH. The study of rheological properties indicated that extracted mucilage solution showed mainly elastic and shear-thinning behavior. Conclusion:The Fourier transform infrared spectra of extracted mucilage exhibited the existence of polysaccharides and protein chains in fenugreek seeds mucilage. The X-ray diffraction corroborated the presence of crystals in the mucilage structure. The proton nuclear magnetic resonance spectra confirmed the polysaccharides and protein composition of extracted mucilage. The maximum mucilage mass loss was observed at 190-350 °C using thermogravimetric analysis.