Structural and Physicochemical Properties of Tunisian Quercus suber L. Starches for Custard Formulation: A Comparative Study.

The aim of the present study was to extract starch from acorn (Quercus suber L.) fruits using water and alkaline methods. Structural and functional properties of extracted starches were investigated and compared to those of corn and modified starches in order to determine their innovative potential application in food industry. The yield of extraction using the two methods was about 48.32% and 48.1%. The isolated starches showed low moisture, fat and protein contents, revealing high purity and quality. Additionally, the starch extracted using the alkaline method (AAS) showed higher lightness (60.41) when compared to starch isolated using hot water (WAS). However, the lightest white color was found for studied commercial starches. Moreover, AAS starch exhibited the highest swelling power, solubility and water absorption, followed by WAS and commercial starches. Results showed that extracted acorn starches were characterized by greater enthalpy and gelatinization temperatures. Similar observations were noted using FT-IR spectra analysis for all analyzed starches. In addition, granule starches observed using scanning electron microscopy were found to be spherical and ovoid. However, from the analysis by X-ray diffraction, a crystalline pattern of C-type was found for acorn starches, while commercial starches presented an A-type pattern. As an innovative food application, these underexploited acorn starches were valued and served to produce new custards with improved functional properties and better microstructure when compared to commercial custard.

Optimization of barley flour and inulin addition for pasta formulation using mixture design approach.

The aim of the present work was to optimize the formulation of a new functional pasta containing durum wheat semolina, whole barley flour, and inulin ingredients to enhance both the technological and textural properties of this product using the mixture design approach. Optimally formulated pasta with acceptable technological and textural properties as close as possible to those of control pasta was studied. The microstructure analysis of cooked and uncooked pasta was performed. Cox response trace plots revealed that the increasing amounts of whole barley flour and durum wheat semolina resulted in an increase in the cooking quality parameters and yellowness. However, pasta firmness was negatively influenced by inulin and whole barley flour addition. The ingredient composition of the optimally formulated pasta, which leads to the best technological and textural properties, was 94.8% durum wheat semolina, 3.7% whole barley flour, and 1.5% inulin. This optimal formulation had an optimal cooking time of 335.24 s, a swelling index of 2.15%, and a cooking loss of 10.44%. The firmness values and the color parameters were also satisfactory. The microstructure of the optimally formulated cooked pasta showed the presence of few not gelatinized starch granules incorporated into the protein matrix as compared to the control pasta. PRACTICAL APPLICATION: Three ingredients, durum wheat semolina, whole barley flour, and inulin, were used for the production of new functional pasta using a mixture design approach. The obtained optimally formulated pasta, with good technological and textural properties, was rich in several dietary fibers. This allows the application of whole barley flour and inulin in the cereal industry and can be of interest to the human diet.

Extraction and Characterization of Tunisian Quercus ilex Starch and Its Effect on Fermented Dairy Product Quality.

In this study, a new starch has been isolated from acorn (Quercus ilex) fruits. The chemical composition of acorn flour showed its richness in carbohydrates (64.43%), proteins (8%), and fat (10%). The extraction yield of acorn starch was about 34.5%. Thus, the composition of extracted acorn starch and its physical and functional properties were studied. Acorn starch had high purity represented by low proportions of proteins (0.92%) and lipids (0.51%) with a pH of 5.3. The swelling power was 20.76 g/g, while the solubility was about 64.22% at 90°C which suggests that acorn starch has potential for use in food industries. The FT-IR spectra of isolated native starches have shown the main bands characterizing the starch. However, X-ray diffractograms exhibited an A- and B-type diffraction pattern. Furthermore, the effect of acorn starch incorporation at different levels (0.5%, 1%, 1.5%, and 2%) on the quality parameters of a fermented dairy product was investigated at the beginning of storage. The results demonstrated that the most suitable dose of acorn starch to be incorporated in the fermented dairy product was lower than 1%. This low concentration reduced syneresis, improved functional properties, and enhanced the viscosity of the fermented dairy product.