Drying of Seabuckthorn (Hippophae rhamnoides L.) Berry: Impact of Dehydration Methods on Kinetics and Quality

Abstract

Convective hot air drying and freeze drying were investigated as potential dehydration processes to obtain powders of seabuckthorn fruit pulp. Halved seabuckthorn fruits were placed in a hot air dryer and dried at 1 m/s and at 50 or 60°C or freeze dried at less than 30 mTorr and at 20 or 50°C shelf plate temperature. An initial characterization of the seabuckthorn pulp (moisture, pH, soluble solid content, vitamins C and E, total phenolics, and carotenoids) was performed. Water loss, total phenolic compounds, total carotenoids, and vitamin C were determined at different processing times. Vitamin E was determined before and at the end of drying.

Freeze-drying kinetics were faster than air drying, probably due to lower moisture diffusion in the compact, sugary, and oily structure of the air-dried tissue. The temperature had an important impact on hot air–drying and freeze-drying kinetics. Drying method and processing times affected the remaining phenolic, carotenoid, and vitamin contents of seabuckthorn berries. Freeze drying was revealed as a superior method to obtain seabuckthorn powders because of the lower residual moisture content, the ease of grinding, as well as the better nutritional retention.

Keywords:

• Freeze drying
• Hot air drying
• Powders
• Seabuckthorn

ACKNOWLEDGMENTS

The authors are thankful to the Association des Producteurs d'Argousier du Québec (APAQ) and NSERC for their financial support. The authors also acknowledge the technical help of Pascal Dubé with the high-performance liquid chromatography analysis (vitamin E) as well as undergraduate students Ann-Julie Duguay and Marie-Claude Verreault for their technical support in the laboratory determinations.

Notes

*p < 0.005 according to analysis of variance using SigmaPlot 10.02 software.^{[ 24 ]} Model parameters were obtained separately according to each experimental condition.

*p < 0.005 according to analysis of variance using SigmaPlot 10.02 software.^{[ 24 ]} Model parameters were obtained separately according to each experimental condition.

*p < 0.005 according to analysis of variance using SigmaPlot 10.02 software.^{[ 24 ]} Model parameters were obtained separately according to each experimental condition.

*p < 0.005 according to analysis of variance using SigmaPlot 10.02 software.^{[ 24 ]} Model parameters were obtained separately according to each experimental condition.