5-Hydroxymethylfurfural Formation in Bread as a Function of Heat Treatment Intensity: Correlations with Browning Indices.

Gabriella Giovanelli,Carola Cappa

doi:10.3390/foods10020417

Abstract

5-hydroxymethylfurfural (HMF) is formed during bread baking as a Maillard reaction product (MRP); it can exert toxicity and it is regarded as a potential health risk because of its high consumption levels in western diets. The aim of this study was to evaluate HMF formation in bread as a function of heat treatment intensity (HTI) and to investigate correlations between HMF and easily detectable browning indices. White breads were baked at 200 °C and 225 °C for different baking times for a total of 24 baking trials. Browning development was evaluated by reflectance colorimetric and computer vision colour analysis; MRP were quantified spectrophotometrically at 280, 360 and 420 nm and HMF was determined by HPLC. HMF concentrations varied from 4 to 300 mg/kg dw. Colour indices (100–L*) and Intensity mean resulted significantly correlated between each other (r = −0.961) and with MRP (r ≥ 0.819). The effects of the different HTI were visualized by principal component analysis and the data were used to evaluate the best fitting regression models between HMF concentration and other browning indices, obtaining models with high correlation coefficients (r > 0.90).

Highlights

Bread is one of the most consumed foods worldwide and it can be produced using different ingredients and processing techniques
A variety of reactions take place, including protein denaturation and starch gelatinization in the crumb and the formation of the crust; this latter is due to dehydration and to the occurrence of reactions that lead to the development of the typical colour and aroma
Water evaporates from the product surface generating an evaporation front that progressively moves towards the core

Summary

Introduction

Bread is one of the most consumed foods worldwide and it can be produced using different ingredients and processing techniques. A variety of reactions take place, including protein denaturation and starch gelatinization in the crumb and the formation of the crust; this latter is due to dehydration and to the occurrence of reactions that lead to the development of the typical colour and aroma. In the outer layer water content decreases and temperature rises above 100 ◦C, asymptotically tending to the oven temperature. These changes lead to the formation of the crust, a region characterised by low moisture content (5–10%) and typical structural characteristics that avoid further dehydration of the crumb, where moisture does not substantially change and temperature remains around 100 ◦C [1]

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Results