PHYSICOCHEMICAL PROPERTIES AND DIGESTIBILITY OF HEAT-MOISTURE-TREATED POTATO STARCH­ SODIUM STEARATE COMPLEXES

• Main Author: Fernita Nurhaini, Feni
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/41390
• Institution: Institut Teknologi Bandung

Sta rchy food is a wid e l y used carbohydra te that is frequently consumed by human. It contributes a lmost 50-65°o to the huma n so urce of energy. In huma n bod y, starch as carbohydrate will be h ydrolyzed ra pidly to result in gl ucose monomers. Consuming ca rbohydrate co ntinuousl y ca n increase th e blood sugar le vel, ca n cause obesity,induce some metabo lic disord ers, such as cardiovascul a r descases, a nd type II d ia betes. In ord er to redu ce those risk s, n ative potato starch (NPS) was phys ica lly modified by heat-mo isture trea tme nt (HMT) a t 125°( (HPS125) a nd 145°( ( HPS145). Then , NPS, HPS I 25, a nd HPS I45 were inclusion complexed with sod ium stearate (SS) as a gu est molecule, therefore, the NPS-SS, HPS 1 25-SS, a nd HPS I 45-SS complexes were obta ined . ln this research, HMT was used to modi fy sta rch ph ysicochemi ca l properties wi thou t entirely ruptu ring starch granules. Moreover. the formation of the inclus ion complexes between the physica lly mod ified starch and odium stearate ca n then reduce the digestibilit y of starc h from ra pidl y to slowly d igesti bl e and resista nt sta rch. The results showed tha t HMT increased the pastin g temperature, while d ecreasing the peak v iscosity of N PS. After complexation, the increase of pasting temperature and the reduction o f the peak v iscos ity va lue were s i gnifica nt. Fu rthermore, the HMT a lso resulted in the lower va lue of NPS swe lling power. The d ecrease of swe lling power was further lowered by increasing the concentratio n of the introduced sodium stea ra te in the complex. The pola rized mic rosco py images of starch d epicted tha t the bire fringence rema ined in the sta rch gra nule a fter HMT. This was al so accompanied by the gela tiniza tion process of th e starch 's hilum as depicted in the bri ght field microscopy images. Genera lly, diffractogram of HPS a nd N PS indicated that 0 ocrysta llinit y of HPS was l ower than NPS. HPS-SS and NPS-SS complexes diffractogra ms a lso presented that HPS-SS had relatively high er 0 ocrysta llin i ty compa red to NPS-SS. In addition, the crysta llinity of two typica l pea ks of the compl exes at 28 1 3° a nd 20° e nha nced as the SS concentration in so lution increased . The increment of crysta llinity could further have a role in the reduction o f sta rch d igestibilit y toward s a - a mi lase. Thermal pro perties ofNPS, HPS, NPS­ SS, a nd HPS-SS were a na lyzed based on the DSC thermograms. DSC the rmograms a t t he first heating cycle displ ayed that th e H PS gelatinization tempera ture (Tp ) was higher than NPS, but the enthalpy gelatinization (t::.Hm) decreased as the HMT temperature increased. It was obtained that !::.Hm NPS, !::.Hm HPS125, and !::.Hm HPS145 was getting higher respectively. The complexes formation was also pro ven by the reduction of t::.H 111 starch at around 60°C as the sodium stearate concentration enhanced. It was also detected that the complex formation led to the appearance of double endothermic peaks at around 115°( and 1 27°( which indicate the melting process of complexes fanned. At the cooling cycle, the exothermic peak was present due to the recrystallization process of complexes. Besid es that, the alternation of starch physicochemical wou ld influence the digestibility of starch. In th e resulting in vitro test, it was displayed that the susceptib ility of starch towards a - amilase decreased after HMT. The significant reduction was obtained at HPS­ SS complexes. It was confirmed by the decrement of reducing sugar released after digestion by a - amilase.