Thermal behaviour of wheat starch and flour at different water levels: Effect of pectins, modified celluloses and NaCl

Rapid viscoanalyser (RVA) and differential scanning calorimetry (DSC) can be applied to study thermal transitions in starch based systems at different water levels. The effect of different hydrocolloids on wheat starch thermal transitions in the presence and absence of NaCl (2%) was evaluated in flour-hydrocolloid suspensions, starch-hydrocolloid mixtures and dough. These hydrocolloids include microcrystalline cellulose (MCC), carboxymethyl cellulose (CMC), two types of hydroxypropylmethylcellulose (HPMC F 4M and F50), a low methoxyl pectin (LMP) and a high methoxyl pectin (HMP). The suspensions were submitted to a heating/cooling cycle in an RVA and a DSC was used to evaluate gelatinization and ALC transition in dough and mixtures. All of the suspensions containing NaCl exhibited higher hot paste stability. Furthermore, CMC and pectins showed an inhibitory effect on amylose retrogradation. Results also showed that starch thermal transitions in limited and excess water can be highly affected by hydrocolloids, particularly when NaCl is present.