Izabel Cristina Freitas Moraes

Influência do grau de hidrólise do poli(vinil álcool) nas propriedades físicas de filmes à base de blendas de gelatina e poli(vinil álcool) plastificados com glicerol

The aim of this work was to study the effect of the Degree of Hydrolysis (DH) of poly(vinyl alcohol) (PVA) on the properties of films based on blends of pigskin gelatin and PVA with two DH. The films were made with solutions with 2 g macromolecules/100 g solution, containing 23.1 g PVA.100 g-1 macromolecules and 25 g glycerol/100 g macromolecules. The mechanical and thermal properties, color, opacity, moisture and solubility of the films were studied, as well as Fourier Transform Infrared (FTIR) spectra. The solutions were analyzed by dynamic rheometry. The films containing PVA with lower DH were more hygroscopic and more soluble. However, the type of PVA did not affect color, but affected the opacity and the gloss of the films. The PVA of higher DH produced films which were more resistant to puncture and stress, and the PVA of lower DH produced films which were more deformable upon stress, although less deformable upon puncture. The DH of PVA did not affect the first scan glass transition temperature of the films, but did affect this property in the second scan. The results from the FTIR analysis were in conformity with the results of the thermal analysis. The viscoelastic properties of the solutions determined by rheometry were not affected by the DH of PVA, possibly because the solutions studied were diluted.

Effect of different polysaccharides and crosslinkers on echium oil microcapsules

Microencapsulation by complex coacervation using gelatin and arabic gum (AG) as wall materials and transglutaminase for crosslinking is commonly used. However, AG is only produced in a few countries and transglutaminase is expensive. This work aimed to evaluate the encapsulation of echium oil by complex coacervation using gelatin and cashew gum (CG) as wall materials and sinapic acid (S) as crosslinker. Treatments were analyzed in relation to morphology, particle size, circularity, accelerated oxidation and submitted to different stress conditions. Rounded microcapsules were obtained for treatments with AG (45.45μm) and microcapsules of undefined format were obtained for treatments with CG (22.06μm). The S incorporation for 12h improved the oil stability by three fold compared to oil encapsulated without crosslinkers. Treatments with CG and S were resistant to different stress conditions similar to treatments with AG and transglutaminase, making this an alternative for delivery/application of compounds in food products.

Production and structural characterization of solid lipid microparticles loaded with soybean protein hydrolysate

The aims of this study were to produce and evaluate solid lipid microparticles (SLMs) loaded with soy protein hydrolysate (HP). The SLMs were produced by spray chilling with an active material and carrier ratio of 1:5 and 1:10 and in two feed preparations: emulsion and suspension. The rheological parameters of the feeds produced by emulsions were studied, morphological characteristics of the SLMs were examined via scanning electron microscopy (SEM) and confocal microscopy, the particle size and distribution were measured via laser light diffraction, and the structural properties of the SLMs were characterized via infrared (FTIR) spectroscopy and X-ray diffraction (XRD). SEM images showed that SLMs were spherical and agglomerated. The analysis of X-ray diffraction indicated that the microparticles after 90days of storage had β polymorphic form. The preparation methods for feeds, emulsion and suspension, had no influence on the rheological parameters, and the median particle size of the SLMs and interactions between the ingredients were not detected via FTIR spectroscopy; however, the SLMs prepared by emulsion contained pores and had a higher incorporation efficiency of HP. The spray chilling technique is suitable method for microencapsulation of soy protein hydrolysate. So, this technique could be useful for attenuating HP unpleasant taste, for its protection and also for promoting its release in the intestine, during fat digestion.

Development of functional yogurt containing free and encapsulated echium oil, phytosterol and sinapic acid

The consumption of omega-3 fatty acids and phytosterol promotes the reduction of cholesterol and triacylglycerol levels. However, such compounds are susceptible to oxidation, which hampers their application. The objective of this work was to coencapsulate echium oil, phytosterols and sinapic acid (crosslinker/antioxidant), and incorporate the obtained microcapsules into yogurt. The microcapsules were evaluated for particle size, accelerated oxidation by Rancimat, and simulation of gastric/intestinal release. The yogurts were assessed for morphology, pH, titratable acidity, color, rheology and sensory analysis. The microcapsules (13-42μm) promoted protection against oil oxidation (induction time of 54.96h). The yogurt containing microcapsules, presented a pH range from 3.89 to 4.17 and titratable acidity range from 0.798 to 0.826%, with good sensorial acceptance. It was possible to apply the microcapsules in yogurt, without compromising the rheological properties and physicochemical stability of the product.

Analysis of Histones H3 and H4 Reveals Novel and Conserved Post-Translational Modifications in Sugarcane.

Histones are the main structural components of the nucleosome, hence targets of many regulatory proteins that mediate processes involving changes in chromatin. The functional outcome of many pathways is “written” in the histones in the form of post-translational modifications that determine the final gene expression readout. As a result, modifications, alone or in combination, are important determinants of chromatin states. Histone modifications are accomplished by the addition of different chemical groups such as methyl, acetyl and phosphate. Thus, identifying and characterizing these modifications and the proteins related to them is the initial step to understanding the mechanisms of gene regulation and in the future may even provide tools for breeding programs. Several studies over the past years have contributed to increase our knowledge of epigenetic gene regulation in model organisms like Arabidopsis, yet this field remains relatively unexplored in crops. In this study we identified and initially characterized histones H3 and H4 in the monocot crop sugarcane. We discovered a number of histone genes by searching the sugarcane ESTs database. The proteins encoded correspond to canonical histones, and their variants. We also purified bulk histones and used them to map post-translational modifications in the histones H3 and H4 using mass spectrometry. Several modifications conserved in other plants, and also novel modified residues, were identified. In particular, we report O-acetylation of serine, threonine and tyrosine, a recently identified modification conserved in several eukaryotes. Additionally, the sub-nuclear localization of some well-studied modifications (i.e., H3K4me3, H3K9me2, H3K27me3, H3K9ac, H3T3ph) is described and compared to other plant species. To our knowledge, this is the first report of histones H3 and H4 as well as their post-translational modifications in sugarcane, and will provide a starting point for the study of chromatin regulation in this crop.

Physicochemical Properties of Maranta (Maranta arundinacea L.) Starch

Maranta (Maranta arundinacea L.) can be considered as a non-conventional raw material for starch. The objective of this work was to characterize the maranta starch. These starch granules had spherical and elongated geometries with average size of 56.60 μm. The maranta starch presented B-type crystal, revealed by x-ray spectra, and gelatinization temperature of 65.5°C as determined by thermal (differential scanning calorimetry) analysis. Maranta starch suspensions have a pseudoplastic behavior which was well described using a power law model. Storage and loss moduli increased drastically during gelatinization process, corroborating with differential scanning calorimetry results. In general, maranta starch could have numerous applications in the food industry.Maranta (Maranta arundinacea L.) can be considered as a non-conventional raw material for starch. The objective of this work was to characterize the maranta starch. These starch granules had spherical and elongated geometries with average size of 56.60 μm. The maranta starch presented B-type crystal, revealed by x-ray spectra, and gelatinization temperature of 65.5°C as determined by thermal (differential scanning calorimetry) analysis. Maranta starch suspensions have a pseudoplastic behavior which was well described using a power law model. Storage and loss moduli increased drastically during gelatinization process, corroborating with differential scanning calorimetry results. In general, maranta starch could have numerous applications in the food industry.

Dehydration of "dedo de moça" pepper: kinetics and phytochemical concentration

A pimenta vermelha e rica em vitamina C e outros fitoquimicos e pode ser consumida como produto desidratado. A avaliacao das melhores condicoes de secagem pode garantir melhor qualidade do produto. Assim, o objetivo deste trabalho foi estudar o efeito da temperatura do ar de secagem (55, 65, 75 oC) sobre a cinetica de secagem, conteudos de vitamina C e fenolicos totais e cor do produto desidratado, comparando-os a pimenta in natura. A desidratacao foi feita por conveccao forcada em estufa. A cinetica de secagem foi determinada por pesagens periodicas ate peso constante. A umidade da pimenta in natura foi de aproximadamente 86%. As curvas de secagem foram ajustadas por tres modelos diferentes, avaliados na literatura. O modelo de Page apresentou o melhor ajuste para este processo. A analise de variância mostrou que a temperatura de secagem influenciou significativamente (p < 0,05) os parâmetros de qualidade (conteudo de vitamina C, conteudo de fenolicos totais, cor) da pimenta desidratada quando comparados aos da pimenta in natura. Apos a secagem, a retencao de vitamina C aumentou com a reducao da temperatura de secagem. De maneira geral, a qualidade do produto foi favorecida na secagem com menor temperatura, devido a reducao nas perdas de compostos bioativos.

Phase transitions in biodegradable films based on blends of gelatin and poly (vinyl alcohol)

The aim of this work was to study the effect of the hydrolysis degree (HD) and the concentration (CPVA) of two types of poly (vinyl alcohol) (PVA) and the effect of the type and the concentration of plasticizers on the phase properties of biodegradable films based on blends of gelatin and PVA, using a response-surface methodology. The films were made by casting and the studied properties were their glass (Tg) and melting (Tm) transition temperatures, which were determined by diferential scanning calorimetry (DSC). For the data obtained on the first scan, the fitting of the linear model was statistically significant and predictive only for the second melting temperature. In this case, the most important effect on the second Tm of the first scan was due to the HD of the PVA. In relation to the second scan, the linear model could be fit to Tg data with only two statistically significant parameters. Both the PVA and plasticizer concentrations had an important effect on Tg. Concerning the second Tm of the second scan, the linear model was fit to data with two statistically significant parameters, namely the HD and the plasticizer concentration. But, the most important effect was provoked by the HD of the PVA.

Influence of osmotic dehydration on ascorbic acid loss in pickled dry peppers (Capsicum chinense)

The objective of this work was (1) to develop a dehydrated pepper with 45% humidity, determining the drying curves for pepper, with and without osmotic pre-treatment and (2) to evaluate the influence of both drying and osmotic treatment on the content ascorbic acid (vitamin C) in fresh pepper and pepper with 45% humidity. The experiments were carried out using the peppers cut in half, with and without osmotic pre-treatment, followed by drying in an oven at 70 oC. The results showed that the osmotic pretreatment did not influence the retention of ascorbic acid during the drying of pepper. The sensory analysis regarding the color, flavor, and texture attributes revealed that there was no difference in the acceptability.

Technological and sensory evaluation of pineapple ice creams incorporating curcumin-loaded nanoemulsions obtained by the emulsion inversion point method

This study evaluated the feasibility of incorporating curcumin-loaded nanoemulsions (CLNE) produced by the emulsion inversion point method in pineapple ice creams to replace artificial yellow dyes. For this purpose, ice creams with formulations: A (pineapple flavour commercial mix), B (partial replacement of commercial mix by CLNE), C (complete replacement of commercial mix by CLNE) and D (complete replacement of commercial mix by nonencapsulated curcumin) were characterized. Results showed that CLNE incorporation was a feasible alternative for reducing the use of artificial dyes, as the ice creams showed similar physicochemical and rheological properties, and formulations A and B had similar sensory acceptance.