Carbohydrate Polymers 86 (2011) 328–336 Contents lists available at ScienceDirect Carbohydrate Polymers j ourna l ho me pag e: www.elsevier.com/locate/carbpol Investigation on structural and physicochemical modifications of standard maize, waxy maize, wheat and potato starches after DIC treatment Z. Maache-Rezzoug a , I. Zarguili b,∗ , C. Loisel c , J-L. Doublier d , A. Buléon e a Laboratoire LEPTIAB, Université de la Rochelle, av. M. Crepeau, 17042 La Rochelle, France b Equipe de Procédés pour l’Energie et l’Environnement, Université Sidi Mohamed Ben Abdellah, Faculté Polydisciplinaire de Taza, BP 1223, Taza, Morocco c Laboratoire GEPEA, ONIRIS rue de la Géraudière, BP 82225, 44322 Nantes Cedex 3, France d UR1268 Biopolymères Interactions Assemblages, INRA, F-44300 Nantes, France e UPCM-INRA, BP 71627, 44316 Nantes, France a r t i c l e i n f o Article history: Received 7 February 2011 Received in revised form 14 April 2011 Accepted 24 April 2011 Available online 1 May 2011 Keywords: Starch DIC ® hydrothermal treatment Gelatinization Crystallinity Functional properties a b s t r a c t This study reports the impact of the Instantaneous Controlled Pressure Drop (DIC ® ) treatment on struc- tural, thermal and functional properties of starches from four botanical origins (standard and waxy maize, wheat and potato, SMS, WMS, WTS and PTS respectively). The structural and functional properties of treated starches were studied using differential scanning calorimetry (DSC), wide-angle X-ray diffrac- tion, optical microscopy and rheological measurements. For cereal starches the resulting modifications were almost identical: increase of the gelatinization temperature and decrease of the transition tempera- ture range that were ascribed to enhanced stability (or size) and cohesion (or homogeneity) respectively of starch crystallites. Potato starch exhibited the reverse tendency according to its particular structural organisation. All the starches showed a reduction of the gelatinization enthalpy as the intensity of the processing conditions increased. The DIC ® treatment seemed to cause total or partial melting of the less stable starch crystallites at low temperatures. As a result, the gelatinization temperatures (To and Tp) of the DIC-treated starches increased; this could be attributed to the melting of the most stable crystallites which needed higher temperature range. Microscopy observations confirmed the partial or total loss of birefringence of treated starch granules. Relative crystallinity decreased upon DIC ® treatment with a larger impact on PTS that became amorphous at 2 bar/12 min. The transition for SMS and WTS from A to Vh-type X-ray diffraction pattern revealed the formation of amylose–lipid complexes induced by the treatment. The Brabender viscosity of cereal starches treated at low pressure and processing time was higher than the one of native starches and was clearly reduced for higher pressure levels. For PTS the Brabender viscosity dramatically decreased for all DIC ® conditions. Rheological properties of treated starches showed the same tendency except the WTS, whose viscosity was reinforced by the hydrothermal treatment at 3 bar/0.5 min. The study showed that the different responses observed on treated starches were mainly influenced by DIC ® processing conditions and by the botanical origin of the starches. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Starch is one of the most important biopolymers in processed foods and has many diverse applications in non-food production. Its unique properties largely contribute to the structure and texture of processed products. Native starches require physical, chemical or enzymatic modifications for a wide range of applications, in order to meet the specific needs of industrial processes. Hydrother- mal treatments (simultaneous action of heat and moisture) belong to physical modification and differ according to the tempera- ∗ Corresponding author at: Université Sidi Mohamed Ben Abdellah, Faculté Poly- disciplinaire de Taza, BP 1223, Taza, Morocco. Tel.: +212 06 18 71 29 49. E-mail address: z ikbal@yahoo.fr (I. Zarguili). ture and moisture content experimented. The two major physical treatments largely cited by the literature that modify the physic- ochemical properties of starch, without destroying the granules are ANNealing (ANN) (Stute, 1992; Tester, Debon, & Sommerville, 2000; Tester & Morrison, 1990) and Heat Moisture Treatment (HMT) (Collado & Corke, 1999; Gunaratne & Corke, 2007; Gunaratne & Hoover, 2002; Hoover & Manuel, 1996; Jacobs et al., 1998; Kulp & Lorenz, 1981; Tester et al., 2000; Tukomane, Leerapongnum, Shobsngob, & Varavinit, 2007; Vermeylen, Goderis, & Delcour, 2006). These two treatments require different water content, tem- perature and time conditions. ANN involves incubation of starch granules in excess of water (>60%, w/w) or at intermediate water content (40–55%, w/w) occur- ring over a large range of processing times (from 0.5 to 144 h, Jyakody & Hoover, 2008) at temperatures above the glass transition 0144-8617/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbpol.2011.04.058