Vânia Zanella Pinto

Effect of single and dual heat-moisture treatments on properties of rice, cassava, and pinhao starches.

The effects of single and dual heat-moisture treatment (HMT) of rice, cassava and pinhão starches at 100 °C and 120 °C were investigated. The starches were adjusted to 22% w.b. moisture content and subjected to single HMT (autoclaved for 2 h) or dual HMT (after being autoclaved for 1 h, the material was allowed to stand for 24 h and was autoclaved again for more 1 h). Starch crystallinity, solubility, swelling power, thermal properties, pasting properties, and gel hardness were evaluated. The temperature variation affected more the starch properties than the single or dual HMT. The starch subjected to single HMT at 120 °C was the most applicable to food applications, where low swelling power, low viscosity and high thermal stability are necessary.

Structure, morphology and functionality of acetylated and oxidised barley starches.

Acetylation and oxidation are chemical modifications which alter the properties of starch. The degree of modification of acetylated and oxidized starches is dependent on the catalyst and active chlorine concentrations, respectively. The objective of this study was to evaluate the effect of acetylation and oxidation on the structural, morphological, physical-chemical, thermal and pasting properties of barley starch. Barley starches were acetylated at different catalyst levels (11%, 17%, and 23% of NaOH solution) and oxidized at different sodium hypochlorite concentrations (1.0%, 1.5%, and 2.0% of active chlorine). Fourier-transformed infrared spectroscopy (FTIR), X-ray diffractograms, thermal, morphological, and pasting properties, swelling power and solubility of starches were evaluated. The degree of substitution (DS) of the acetylated starches increased with the rise in catalyst concentration. The percentage of carbonyl (CO) and carboxyl (COOH) groups in oxidized starches also increased with the rise of active chlorine level. The presence of hydrophobic acetyl groups, carbonyl and carboxyl groups caused a partial disorganization and depolymerization of starch granules. The structural, morphological and functional changes in acetylated and oxidized starches varied according to reaction conditions. Acetylation makes barley starch more hydrophobic by the insertion of acetyl groups. Also the oxidation promotes low retrogradation and viscosity. All these characteristics are important for biodegradable film production.

Development of oxidised and heat-moisture treated potato starch film.

This study investigated the effects of sodium hypochlorite oxidation and a heat-moisture treatment of potato starch on the physicochemical, pasting and textural properties of potato starches in addition to the water vapour permeability (WVP) and mechanical properties of potato starch films produced from these starches. The carbonyl contents, carboxyl contents, swelling power, solubility, pasting properties and gel texture of the native, oxidised and heat-moisture treated (HMT) starches were evaluated. The films made of native, oxidised and HMT starches were characterised by thickness, water solubility, colour, opacity, mechanical properties and WVP. The oxidised and HMT starches had lower viscosity and swelling power compared to the native starch. The films produced from oxidised potato starch had decreased solubility, elongation and WVP values in addition to increased tensile strength compared to the native starch films. The HMT starch increased the tensile strength and WVP of the starch films compared to the native starch.

Polishing and parboiling effect on the nutritional and technological properties of pigmented rice

This study aims to evaluate the effects of polishing and parboiling on proximate composition, structure, phenolic compounds, antioxidant activity, cooking time and hardness of IAC-600 black rice cultivar and MPB-10 red rice lineage. Proximate analysis and light micrographs revealed higher migration of red rice proteins than black rice proteins to the endosperm as a result of parboiling. Parboiling reduced the ash content of red rice while no difference was determined in black rice. Gelatinized starch granules from both genotypes showed similar appearance. There was a decrease in relative crystallinity on both black and red rice subjected to parboiling, which was an indicative of crystallites disruption. Polishing removed more than 90% of free phenolics for both genotypes, while parboiling allowed the partial preservation of free phenolics content in polished rice. Parboiling induced an increase in the cooking time of red rice, but a decrease in the cooking time of black rice.

Effects of single and dual physical modifications on pinhão starch

Pinhão starch was modified by annealing (ANN), heat-moisture (HMT) or sonication (SNT) treatments. The starch was also modified by a combination of these treatments (ANN-HMT, ANN-SNT, HMT-ANN, HMT-SNT, SNT-ANN, SNT-HMT). Whole starch and debranched starch fractions were analyzed by gel-permeation chromatography. Moreover, crystallinity, morphology, swelling power, solubility, pasting and gelatinization characteristics were evaluated. Native and single ANN and SNT-treated starches exhibited a CA-type crystalline structure while other modified starches showed an A-type structure. The relative crystallinity increased in ANN-treated starches and decreased in single HMT- and SNT-treated starches. The ANN, HMT and SNT did not provide visible cracks, notches or grooves to pinhão starch granule. SNT applied as second treatment was able to increase the peak viscosity of single ANN- and HMT-treated starches. HMT used alone or in dual modifications promoted the strongest effect on gelatinization temperatures and enthalpy.

Acetylated rice starches films with different levels of amylose: Mechanical, water vapor barrier, thermal, and biodegradability properties

Biodegradable films from native or acetylated starches with different amylose levels were prepared. The films were characterized according to the mechanical, water vapor barrier, thermal, and biodegradability properties. The films from acetylated high amylose starches had higher moisture content and water solubility than the native high amylose starch film. However, the acetylation did not affect acid solubility of the films, regardless of the amylose content. Films made from high and medium amylose rice starches were obtained; however low amylose rice starches, whether native or acetylated, did not form films with desirable characteristics. The acetylation decreased the tensile strength and increased the elongation of the films. The acetylated starch-based films had a lower decomposition temperature and higher thermal stability than native starch films. Acetylated starches films exhibited more rapid degradation as compared with the native starches films.

Black bean (Phaseolus vulgaris L.) protein hydrolysates: Physicochemical and functional properties.

Black bean protein hydrolysates obtained from pepsin and alcalase digestions until 120min of hydrolysis were evaluated by gel electrophoresis, relative fluorescence intensity, emulsifying properties, light micrograph of emulsions and in vitro antioxidant activity. The emulsion stability of the bean protein hydrolysates were evaluated during 30days of storage. The pepsin-treated bean protein hydrolysates presented higher degree of hydrolysis than the alcalase-treated protein hydrolysates. The alcalase-treated bean protein hydrolysates showed higher surface hydrophobicity. Moreover, the protein hydrolysates obtained with alcalase digestion presented higher emulsion stability during 30-days than those obtained from pepsin digestion. The protein concentrate and especially the hydrolysates obtained from alcalase digestion had good emulsion stability and antioxidant activity. Thus, they could be exploited as protein supplements in the diet as nutritional and bioactive foods.

Antimicrobial electrospun ultrafine fibers from zein containing eucalyptus essential oil/cyclodextrin inclusion complex

The aim of this study was to produce ultrafine fibers from zein incorporated with a complex of eucalyptus essential oil (EEO) and β-cyclodextrin (β-CD) with antimicrobial properties by electrospinning technique. The EEO was characterized by chemical composition and antimicrobial tests against three Gram positive and four Gram negative bacteria. The inclusion complex (IC) was prepared with β-CD and EEO by co-precipitation technique and added at different concentrations in zein polymer solution using aqueous ethanol as solvent. The morphology, thermal properties, functional groups, and antimicrobial activity against L. monocytogenes and S. aureus of the ultrafine fibers were evaluated. The composite membranes containing 24% IC exhibited a greater reduction of growth as compared to the fibers without addition of IC. For L. monocytogenes the growth reduction was 28.5% and for S. aureus it was 24.3%. The electrospun IC-β-CD/EEO composite membranes are promising for use in antimicrobial applications, such as food packaging.

Starch digestibility and molecular weight distribution of proteins in rice grains subjected to heat-moisture treatment.

The objective of this study was to evaluate the effects of the heat-moisture treatment (HMT) applied to paddy rice grains on the physicochemical properties, in vitro starch digestibility, and molecular weight distribution of proteins in rice flour. The paddy rice grains were adjusted to 13%, 16%, and 18% moisture and autoclaved at 121°C for 30 and 60min. The HMT promoted a reduction of the amylose content, the swelling power, and the solubility of the rice flour. Changes in the relative crystallinity and molecular weight of the proteins extracted with a sodium phosphate buffer containing 2.0% sodium dodecyl sulfate (SDDS) were observed in HMT samples. The different methods for the quantification of resistant starch resulted in distinct resistant starch contents. The HMT (18%-60min) promoted an increase in resistant starch content and the HMT (16%-60min) caused an increase in the slowly digestible starch in the rice flour.

Films based on oxidized starch and cellulose from barley

Starch and cellulose fibers were isolated from grains and the husk from barley, respectively. Biodegradable films of native starch or oxidized starches and glycerol with different concentrations of cellulose fibers (0%, 10% and 20%) were prepared. The films were characterized by morphological, mechanical, barrier, and thermal properties. Cellulose fibers isolated from the barley husk were obtained with 75% purity and high crystallinity. The morphology of the films of the oxidized starches, regardless of the fiber addition, was more homogeneous as compared to the film of the native starch. The addition of cellulose fibers in the films increased the tensile strength and decreased elongation. The water vapor permeability of the film of oxidized starch with 20% of cellulose fibers was lower than the without fibers. However the films with cellulose fibers had the highest decomposition with the initial temperature and thermal stability. The oxidized starch and cellulose fibers from barley have a good potential for use in packaging. The addition of cellulose fibers in starch films can contribute to the development of films more resistant that can be applied in food systems to maintain its integrity.