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Ingredient Characterization and Hardening of High‐Protein Food Bars: an NMR State Diagram Approach
Author(s) -
Li Yun,
Szlachetka Kristin,
Chen Paul,
Lin Xiangyang,
Ruan Roger
Publication year - 2008
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem-85-6-0780
Subject(s) - chemistry , soy protein , water activity , food science , softening , ingredient , polyol , pea protein , hardening (computing) , relaxometry , chemical engineering , water content , organic chemistry , materials science , composite material , geotechnical engineering , layer (electronics) , polyurethane , engineering , medicine , spin echo , magnetic resonance imaging , radiology
A second‐degree simplex lattice mixture design was used to study the effects of soy, dairy, and soy‐dairy blends of powdered proteins in three high‐protein food bar models (sugar syrup, polyol syrup, and reduced‐sugar syrup). Overall protein performance was evaluated based on textural changes during accelerated storage, bar integrity, and dough stickiness and was a strong function of the syrup model used ( R 2 = 92.33%). Nuclear magnetic resonance (NMR) relaxometry was used to measure relaxation times (T 2 , T 2 *, and T 1 ) at 20°C and to create state diagrams (temperature, T 2 * curves) for the individual powdered proteins and syrups over a temperature range of –35 to 50°C. Increases in relaxation times for powdered protein samples were indicative of better overall protein performance, whereas increases in relaxation times for syrup samples were associated with increases in moisture content and concentration of polyols. Increases in water activity ( a w ) of the bars during accelerated storage suggested an elevated rate of hardening for polyol‐containing bars that was caused by a decrease in the amount of water capable of acting as a plasticizer in the product. Proteins were separated into four types (A, B, C, and D) based on the shape of the state diagram curve. Predicted to be the most stable, type D proteins (SUPRO 313 and SUPRO 430) offered the most versatility and, when blended with other proteins, often induced synergistic softening effects in the nutrition bars which led to an extended product shelf life. The NMR state diagram technique appears to be a valuable tool for predicting overall performance of powdered proteins in sugar‐, polyol‐, and reduced‐sugar syrup based food bars.