RESUMEN
Effect of hydrothermal modifications (autoclaving, annealing and heat moisture treatment) on physico-chemical, rheological properties and in vitro digestibility of kithul starch was studied. Annealing and heat moisture treatment decreased swelling index, solubility and increased crystalline properties as compared with autoclaving. Autoclaving, annealing and heat moisture treatment caused significant morphological damages such as large holes and fissures on the kithul starch, in addition, granules changed from oval to donut shape. Heat moisture treatment formed higher number of agglomerated starch granules. Light transmittance decreased after hydrothermal modifications. Autoclaving and annealing increased the pasting viscosities (except break down viscosity) of kithul starch. A significant increase (p ≤ 0.05) in peak temperature, conclusion temperature and enthalpy was found in annealed and heat moisture treated kithul starches. The digestibility of kithul starch decreased with increasing resistant starch after annealing and heat moisture treatment. Autoclaved, annealed and heat moisture treated kithul starches exhibited higher value of storage modulus (G') and loss modulus (Gâ³) than native kithul starch. It entail to higher firmness of modified starch gel. The current study showed that the remarkable changes formed by hydrothermal modifications increased the industrial acceptance of kithul starch.
RESUMEN
The changes in physico-chemical and rheological properties of kithul starch by the impact of energetic neutral nitrogen atoms produced by the glow discharge air plasma with novel technique were analysed. Here, treatment was carried out at different power levels (5â¯W & 15â¯W) and treatment time (30â¯min & 60â¯min). Decrease in amylose and moisture content and increase in swelling index and solubility of plasma treated kithul starch were observed. Fourier transform infrared spectra of plasma treated starch showed variation in the peaks corresponding to CH2 and OH groups. Relative crystallinity significantly (pâ¯≤â¯0.05) decreased after plasma treatment. Scanning electron microscopy showed severe damages on the starch granular surface by the effect of energetic neutral nitrogen atoms. Pasting properties increased and thermal properties showed significant (pâ¯≤â¯0.05) changes after plasma treatment. Storage modulus (G') and loss modulus (Gâ³) reduced at higher levels of plasma power and it indicated to its weak gel formation.
Asunto(s)
Nitrógeno/química , Gases em Plasma , Almidón/química , Arecaceae/química , Arecaceae/metabolismo , Microscopía Electrónica de Rastreo , Reología , Solubilidad , Espectroscopía Infrarroja por Transformada de Fourier , TemperaturaRESUMEN
The objective of this study was to determine the effect of physical and chemical modifications on the physicochemical and in vitro digestibility of kithul starch. Starch isolated from kithul flour (Caryota urens) was subjected to physical and chemical modifications. The starch modification was verified by the presence of functional groups using Fourier transform Infrared spectral analysis (FT-IR). X-ray Diffraction (XRD) pattern revealed that the kithul starch is A- type and the modifications did not change the crystalline pattern. However, the relative crystallinity showed significant changes. Chemical modifications increased the swelling and solubility. Pasting and thermal parameters of all modified starches showed significant changes as compared to native starch (NS). Acetylated oxidised starch (AOS) showed highest paste viscosities. Higher enthalpy of gelatinization (∆Hgel) and paste viscosity attributed to perfection and ordering of amorphous regions in annealed starch (ANS). All modifications significantly increased the resistant starch (RS) content than native starch (NS), which indicates its lower digestibility. The current study showed the single, dual chemical modifications and annealing, effectively modified the physicochemical and in vitro digestibility of kithul starch.