Effects of Drying Methods on Functionality of a Native Potato Protein Concentrate

Abstract

Pulp and dilute fruit water (PFW) are by-products from the potato starch processing industry. Potato protein obtained from an expanded bed adsorption (EBA) process is a value-added protein concentrate that can offer special technical properties in food systems. The influence of drying techniques on the physiochemical, quality, and functional properties (color, water content, bulk density, rehydration properties, sorption isotherms, specific enzyme activity, solubility, protein denaturation) of dehydrated potato water effluent was investigated. The results indicate that atmospheric freeze drying (AFD) is a more gentle drying process than spray drying and vacuum freeze drying. Both enthalpy measurements and sorption isotherms indicate reduced protein denaturation of AFD samples, while specific enzyme activity is at the same level for all dried samples.

Keywords:

• Atmospheric freeze drying
• Quality
• Sorption isotherms
• Spray drying
• Vacuum freeze drying

ACKNOWLEDGEMENT

Ellen Sivertsen and Anne Birgit Bævre of Matoforsk and Per Egil Gullsvåg, Inga Marie Aasen, and Ola Jonassen of SINTEF are thanked for their assistance with several measurements. The work was supported by the Norwegian Research Council grant no 154438.

Notes

¹The determination of nitrogen according to Kjeldahl using block digestion and steam destillation. Perstorp Analytical Tecator AB. 11.

^∗Small amount of product samples.

The figures are given as mean values for the four pH values 3.5, 4.0, 5.0, and 6.0 and in 0.2 M NaCl. Different hypertext letters indicate significantly different samples. The calorimetric enthalpy is based on total protein content. Complex modulus is reported at 18°C following the heating and cooling steps.