Pressure-temperature phase diagrams of maize starches with different amylose contents

Effect of electron beam irradiation on granular cold-water swelling chestnut starch: Improvement of cold-water solubility, multiscale structure, and rheological properties

In this study, granular cold-water swelling (GCWS) starch was prepared from chestnut starch by ethanol-alkali method, after which it was further modified by electron beam irradiation (EBI) technique to investigate the effect of EBI on GCWS chestnut starch. It was shown that the alcohol-alkali treatment disrupted the starch double helix structure and the starch crystalline form had been changed from "C" to "V" type. On this basis, EBI continued to act on the disrupted starch chains and further cleaved the long chains into short chains, which significantly improved the solubility of starch to 90.08 % in cold water at a 24 kGy irradiation dose. Therefore, this study can broaden the application scope of starch and provide new ideas for GCWS starch applications in food and water-soluble pharmaceutical industries.

Effects of the Amylose/Amylopectin Content and Storage Conditions on Corn Starch Hydrogels Produced by High-Pressure Processing (HPP)

In this study, the effects of the amylose/amylopectin content on starch gelation and the physical characteristics of hydrogels produced by HPP were studied by optical and rheological measurements in steady-state conditions. Additionally, the effects of the storage temperature (4 °C and 20 °C) and type of packaging (plastic bags or sealed Petri dishes) on the physical stability of the hydrogels were evaluated for 30 days of storage by evaluating the shrinkage of the granules, as well as the weight loss, water activity, organoleptic, and rheological properties. The experimental findings suggested that amylose plays an antagonistic role in determining the capacity of the starch granules to absorb water under pressure and to create stable and structured gels and on the physical stability of hydrogels due to its influence over the starch retrogradation extent during storage. Twenty per cent amylose was the minimum concentration to form stable corn starch HPP hydrogels with good physical and rheological properties. Moreover, a storage temperature of 20 °C and the use of polymeric bags were evaluated as the most suitable storage conditions and packaging materials enabling the long storage of corn starch hydrogels.

Physicochemical Properties of Soft and Hard-type Rice Flour According to Moisture Content and High Hydrostatic Pressure Treatment

This study investigated the effects of high hydrostatic pressure (HHP) treatment on the physicochemical properties of rice flour according to its moisture levels in order to develop new materials for processed rice foods. The rice varieties used were the Samkwang variety (normal and hard type) and the Shingil variety (processing and soft type). The moisture content of the rice flour was adjusted to 35-55% and it was treated with the HHP treatment at 400-600 MPa. The water absorption capacity, solubility, and swelling power of the rice flour increased as the moisture levels and pressure increased. The 600 MPa enzymatic hydrolysis-treated rice flour showed similar results to the heat-treated rice flour. Scanning electron microscopy showed few cavities, resulting in a dense structure. X-ray diffraction confirmed that the 23° peak, which indicates the degree of gelatinization, decreased with increasing moisture levels and pressure. The HHP treatment of the rice flour changed its physicochemical properties according to the moisture levels and pressure applied. These results can provide important information on the development and production of various foods.

The Effects of Novel Thermal and Nonthermal Technologies on the Properties of Edible Food Packaging

Edible packaging is influenced by factors such as formulation, production technology, and solvent and additive properties. With the increase in the request for coating and film quality, appropriate form, and high product safety and storage period, various technologies such as high hydrostatic pressure, irradiation, ultrasound, high-pressure homogenization, cold plasma, and microwave have been reviewed. The present study states definitions and mechanisms of novel technologies. The experimental condition, packaging matrix, and the results pertaining to the effects of these technologies on various types of edible packaging is also discussed. The most of the matrix used for packaging was whey protein, soy protein isolate, chitosan, and gelatin. The technologies conditions such as power, frequency, time, temperature, dose, pressure, and voltage can have a significant influence on the application of them in film and coating. Therefore, finding the optimum point for the features of the technologies is important because improper use of them reduces the properties of the edible packaging.

Potato Starch Hydrogels Produced by High Hydrostatic Pressure (HHP): A First Approach

Starch-based hydrogels have received considerable interest due to their safe nature, biodegradability and biocompatibility. The aim of this study was to verify the possibility of producing natural hydrogels based on potato starch by high hydrostatic pressure (HHP), identifying suitable processing conditions allowing to obtain stable hydrogels, as well as to characterize structural and mechanical properties of these products. Sieved (small size granules and medium size granules) and unsieved potato starch samples were used to prepare aqueous suspensions of different concentrations (10-30% w/w) which were processed at 600 MPa for 15 min at different temperatures (25, 40 and 50 °C). Products obtained were characterized by different techniques (light and polarized microscopy, Fourier transform infrared spectroscopy (FTIR), rheology and differential scanning calorimetry (DSC)). Results obtained so far demonstrated that potato starch suspensions (20% starch-water concentration (w/w)) with granules mean size smaller than 25 µm treated at 600 MPa for 15 min and 50 °C showed a complete gelatinization and gel-like appearance. Potato HHP hydrogels were characterized by high viscosity, shear-thinning behavior and a highly structured profile (G' >> G''). Moreover, their FTIR spectra, similarly to FTIR profiles of thermal gels, presented three absorption bands in the characteristic starch-gel region (950-1200 cm-1), whose intensity increased with decreasing the particle size and increasing the processing temperature. In conclusion, potato starch hydrogels produced by HHP in well-defined processing conditions exhibited excellent mechanical properties, which can be tailored according to the requirements of the different applications envisaged.

Conjugation of bovine serum albumin and glucose under combined high pressure and heat

The effect of combined heat and pressure on the Maillard reaction between bovine serum albumin (BSA) and glucose was investigated. The effects in the range of 60-132 °C and at 0.1-600 MPa on the lysine availability of BSA were investigated at isothermal/isobaric conditions. The kinetic results showed that the protein-sugar conjugation rate increased with increasing temperature, whereas it decreased with increasing pressure. The reaction followed 1.4th order kinetics at most conditions investigated. A mathematical model describing BSA-glucose conjugation kinetics as a function of pressure and temperature is proposed. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were used to verify BSA-glucose conjugation and to identify the glucosylated sites. These indicated that the application of combined high pressure and high temperature resulted in significant differences in the progression of the Maillard reaction as compared to heat treatments at atmospheric pressure.