Complementary tools to interpret the role of water as related to structure and functionality of cereal food products

CUETO, M. A.; RODRÍGUEZ, SILVIO DAVID; BUERA, MARÍA DEL PILAR; ROLANDELLI, GUIDO; FARRONI, ABEL E.

New Orleans

Congreso; 255th Annual Meeting American Chemical Society. Water in foods Symposium; 2018

American Chemical Society

Abstract: The objective of this work is to present how several complementary tools can be combined in order tointerpret the impact of water and its interactions with solids, which are useful to define processing and storageconditions in order to obtain desired cereal products.Maize flours and formulations containing milled chia or quinoa seeds were prepared for developing cereal products byhydrothermal/flaking treatment or by extrusion technology. Thermal transitions were analyzed by differential scanningcalorimetry, water sorption isotherms were obtained at 25 ° C and transversal relaxation times of proton magnetization(T2), obtained by 1 H-NMR were studied after a single pulse of 90 ° or after Hahn and CPMG pulse-sequences. Thedistributions of relaxation times were also determined. Spectral changes of the different systems were evaluatedemploying FTIR and multivariate analysis. Starch crystallinity was analyzed by XRD analysis.By means of the analysis of the relaxation times T2, the presence of populations of protons of different mobility wasverified, which allowed to define clearly the different stages of sorption and to explain the characteristics of the productin relation to the water content. Spectral analysis employing multivariate techniques was helpful to select the IRfrequencies which allowed a rapid and non-destructive discrimination between sample processing and compositionalaspects. Correlations between the textural behavior, physical properties and the proposed FTIR indexes wereobtained, which were useful to track changes promoted by extrusion both at molecular and macroscopic levels. Starchcrystallinity loss after extrusion averaged 50 %, showing evidence of amylose-lipid complexes and XRD analysis datacorrelated with FTIR selected variables. The changes related to formulation or processing conditions were reflected inthe microstructure of the products and in their dynamic modifications, including the kinetics of deterioration reactions,color changes or loss of functional ingredients. The complementary techniques employed provided data of motions atthe molecular level that could facilitate interpreting thermal and mechanical properties, based on supramolecularinteractions. These aspects depend on the presence and quantity of water and are relevant in assessing the quality ofcereal products, playing a decisive role in the design of innovative products with defined characteristics.(No Image Selected)