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BACKGROUND Calcium pectinate (CaP) gel is traditionally prepared by de‐esterifying high methoxyl pectin (HMP) to low methoxyl pectin (LMP), followed by gelation with calcium. To save both time and cost in the production of CaP gel, an alternative method was developed by the addition of CaCl2 to HMP at alkaline pH. To optimize the production, response surface methodology (RSM) was used to investigate the effects of temperature (30–50 °C), time (20–40 min) and pH (8–10) on yield, calcium content of the CaP gel and the degree of esterification (DE) of pectin following decalcification of CaP (DC‐pectin). RESULTS The linear term for pH had a significant effect (P < 0.01) on all three responses, whereas interaction effects were not significant (P > 0.01), except on the calcium content (P < 0.01). The optimized process conditions (temperature, time and pH) to obtain maximum CaP‐HMP gel yield (88.83%) were 50 °C, 40 min and pH 9.6, and for the highest calcium content (97.23 mg g–1) they were 40 °C, 30 min and pH 9.7. DC‐pectin was a typical LMP with DE varying from 26.92% to 50.33%. The DE of DC‐pectin could be predicted by a model that proved significant (R2 = 0.9888). CONCLUSION The optimum conditions were established to produce CaP gels from HMP with high yield and calcium content. Also, LMP with predictable DE can be produced following a significant model. This study provides new insights into the production and application of CaP gel. © 2021 Society of Chemical Industry.

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To explore the effects of high-pressure processing (HPP) pretreatment on pectin extraction from pomelo albedo, the extraction yield, and characteristics of pectin were compared with those obtained via traditional acid (A-pectin) extraction. Three different pressures (300, 450, and 600 MPa) and holding times (0, 5, and 10 min) were applied to the fresh albedo, followed by acid extraction. The yield, degree of esterification (DE), galacturonic acid (GalA) content, Fourier transform-infrared (FT-IR) spectra, and rheological properties of pectin were investigated. By comparison with A-pectin, the yield increased by more than two and four times at 300 MPa at holding times of 5 and 10 min, respectively. All extracted pectins were high methoxyl pectins (DE of 76.30-87.83%) with high GalA content (62.3-86.60%); however, there were significant decreases in DE and GalA content when pressure was increased to 600 MPa in comparison with A-pectin. The pressure level and holding time significantly influenced the viscosity of pectin, and HPP-pectin 300-5, 450-10, and 600-0 exhibited a much higher viscosity than A-pectin. Consequently, this study demonstrated that HPP pretreatment of fresh albedo can increase extraction yield and/or alter pectin characteristics for further industrial applications.