Vacuum modification of partial-baked wheat bread: Evaluation of the physicochemical, microstructural properties and acrylamide content

Abstract

In this study, vacuum modification was applied after partial-baking yeast-leavened wheat bread, and its texture parameters, total mass loss during baking, water activity, acrylamide content, bread crumb morphology, starch gelatinisation and starch crystallinity were investigated. In the first part of the study, vacuum modification level was defined by analysing soluble starch, water activity and total mass loss of micro-bread samples (bread without fermentation). Vacuum modification was conducted at negative pressure levels of 30 kPa, 50 kPa, 70 kPa and 90 kPa, and the bread samples were held at these pressure levels for periods of 30 s (VM-GV30) and 60 s (VM-GV60). Effective vacuum modification level was determined by principal component analysis using clustering control and vacuum-modified samples. As a result of PCA, vacuum modification was conducted to the VM-GV60 parameter on yeast-leavened bread samples after partial-baking at 220 °C. Similar hardness values were observed between control and vacuum-modified bread and vacuum modified samples had 59.8% lower acrylamide content. DSC and XRD analyses revealed a stronger amylose-lipid complex for that sample. Vacuum modification was highly effective in reducing acrylamide content in bread crust with the desired texture and color of bread.