Non-enzymatically hydrolyzed guar gum and orange peel fibre together stabilize the low-fat, set-type yogurt: A techno-functional study

Abstract

A combined integration of partially hydrolysed guar gum (PHGG) and orange peel fibre (OPF) into low-fat, set-type yogurt was explored. PHGG was produced using steam hydrolysis assisted by ultra-sonication while OPF (coarse fraction) was prepared from the dried orange peels. PHGG and OPF were further studied for their structural, physical, physico-chemical and rheological characteristics. PHGG exhibited shear thickening and Newtonian behaviour while, OPF showed shear thickening and non-Newtonian behaviour. Size determination of PHGG and OPF adjudged them as fine and coarse fibres, respectively. Four groups of yogurt were prepared by varying the concentration of PHGG (0–0.5% w/v) while, OPF (0.1% w/v) was kept constant. PHGG and OPF formed complimentary fibre networks which stabilized the yogurt gel by acting as filler and bridging agent, respectively. PHGG 0.25% (w/v) + OPF fortified yogurt presented superior rheological, textural and physico-chemical properties in comparison to plain and other fortified yogurts during storage (28 days, 4 °C). Scanning electron microscopy showed that fibre fortified yogurts had more structured and compact casein network as compared to plain yogurt. Thus, fortification with a combination of dietary fibres can not only improve the techno-functional properties of low-fat, set-type yogurt but also provide health benefits of dietary fibre and phytochemicals.