Synthesis and evaluation of n-octenyl succinylated guar gum as an anti-staling agent in bread

Hydrophobicity was introduced in the structure of guar gum (GG) by esterification with n-octenyl succinic anhydride (OSA), forming GG-OSA. This modification was evaluated by FTIR. Maximum degree of substitution of 0.025 was achieved by reacting GG with 0.4 mol OSA/mol of repeating unit of GG at 100 °C for 5 h using 0.5 equivalence of NaHCO3. This GG-OSA, with the introduced partial hydrophobicity, was evaluated for its effect on bread staling and glycaemic index (GI), primarily in comparison to diacetyl tartaric and fatty acid esters of glycerol (DATEM) and GG, respectively. GG-OSA demonstrated potential bread dough strengthening ability by improving its cohesiveness and hardness. On day 4, X-ray diffraction studies on bread containing GG-OSA at 2.5 g/kg (4.10%) indicated crystallinity closer to that containing DATEM at 4 g/kg (4.24%) and lower than control (6.86%) and GG (5.26%). This was corroborated with day 4 crumb firmness for breads containing GG-OSA (18.29 N) and DATEM (19.92 N). The GI of control bread was higher than experimental samples, although there was no statistically significant difference between samples containing the additives chosen in this study. Thus GG-OSA could be used as an effective anti-staling agent in bread.