Combined effect of ultrasound and vacuum impregnation for the modification of apple tissue enriched with aloe vera juice.

The aim of the work was to investigate how ultrasonic (US) treatment impacts on the physical and chemical properties of vacuum-impregnated apples. Apple slices were subjected to vacuum impregnation (VI) in an Aloe vera juice solution without additional treatments, serving as the reference material. Alternatively, ultrasound (US) treatments, at frequencies of 25 or 45 kHz, and durations of 10, 20, or 30 min, were employed as a pre-treatments before the VI process. The use of US processing enabled a significant increase in the efficiency of VI, without influencing in a significant way the color of the VI samples. The VI process led to a reduction in the content of bioactive compounds, in particular vitamin C and TPC decreased by 34 and 32 %, respectively. The use of US as a pre-treatment, in particular at 45 kHz for 20 or 30 min, led to a better preservation of these compounds (unchanged values for vitamin C and decrease by 23-26 % for TPC in comparison to the fresh samples). Through cluster analysis encompassing all assessed properties, it was evident that US treatment was beneficial for the processing, however the application of appropriate parameters of US treatment (frequency and time) had an impact on achieving similar quality to VI samples. The ultrasound treatment before vacuum impregnation may be suitable, however, the specific processing parameters should be defined for the obtained high quality of the final product.

Effect of the Pulsed Electric Field Treatment on Physical, Chemical and Structural Changes of Vacuum Impregnated Apple Tissue in Aloe Vera Juices.

Vacuum impregnation (VI) stands as a diffusion-driven food processing method that has found recent application within the food industry, particularly for the cold formulation of fortified food products. Pulsed electric field (PEF) treatment can affect the food structure, influencing therefore the mass transfer phenomena during the further processing. Thus, the study aimed at investigating the effect of PEF treatment on selected physicochemical properties of vacuum-impregnated apples. Apple slices were vacuum impregnated with aloe vera juice solution with or PEF treatment at different intensities (125, 212.5 or 300 V/cm). The PEF was applied as a pretreatment-applied before the VI process as well as posttreatment-applied after the VI process. The VI process with aloe vera juice resulted in a sample weight increase of over 24% as well as structural changes, partial cell viability loss and color alteration. In addition, the decrease of bioactive compounds was observed, while antioxidant activity remained at a similar level as in raw material. PEF treatment adversely affected vacuum impregnation efficiency, causing microstructural changes and cell viability loss. Additionally, chemical composition modifications were evident through thermogravimetric analysis (TGA) and Fourier Infrared Spectroscopy (FTIR) analyses. Tissue hardness decreased significantly due to structural damage and caused high leakage from plant tissue, which resulted in hindering saturation with aloe vera juice during the VI process. Additionally, reduced bioactive substance content after PEF treatment was observed and the VI process did not restore apple samples of the bioactive compounds from aloe vera juice.

Developments in Plant Proteins Production for Meat and Fish Analogues.

In recent years, there have been significant developments in plant proteins production for meat and fish analogues. Some of the key developments include the use of new plant protein sources such as soy, legumes, grains, potatoes, and seaweed, as well as insect proteins, leaf proteins, mushrooms, and microbial proteins. Furthermore, to improve the technological and functional properties of plant proteins, they can be subjected to traditional and unconventional treatments such as chemical (glycosylation, deamidation, phosphorylation, and acylation), physical (pulsed electric fields, ultrasound, high hydrostatic pressure, dynamic high-pressure treatment, and cold plasma), and biological (fermentation and enzymatic modification). To obtain the high quality and the desired texture of the food product, other ingredients besides proteins, such as water, fat, flavors, binders, dyes, vitamins, minerals, and antioxidants, also have to be used. The final product can be significantly influenced by the matrix composition, variety of ingredients, and water content, with the type of ingredients playing a role in either enhancing or constraining the desired texture of the food. There are several types of technologies used for meat and fish analogues production, including extrusion, shear cell technology, spinning, 3D printing, and others. Overall, the technologies used for meat and fish analogues production are constantly evolving as new innovations are developed and existing methods are improved. These developments have led to the creation of plant-based products that have a similar texture, taste, and nutritional profile to meat and fish, making them more appealing to consumers seeking alternatives to animal-based products.

Rheological and Viscoelastic Properties of Chitosan Solutions Prepared with Different Chitosan or Acetic Acid Concentrations.

Chitosan (Ch) is a partially crystalline biopolymer, insoluble in pure water but soluble in acid solutions. It has attracted interest from researchers to prepare solutions using different acid types and concentrations. This research aims to study both the effect of chitosan (Ch) or acetic acid (Ac) concentrations, at different temperatures, on rheological and viscoelastic properties of Ch solutions. To study the effect of Ch, solutions were prepared with 0.5−2.5 g Ch/100 g of solution and Ac = 1%, whereas to study the effect of Ac, the solutions were prepared with 2.0 g of Ch/100 g of solution and Ac = 0.2−1.0%. Overall, all analyzed solutions behaved as pseudoplastic fluid. The Ch strongly affected rheological properties, the consistency index (K) increased and the index flow behavior (n) decreased as a function of Ch. The activation energy, defined as the energy required for the molecule of a fluid to move freely, was low for Ch = 0.5%. The effect of Ac was less evident. Both K and n varied according to a positive and negative, respectively, parabolic model as a function of Ac. Moreover, all solutions, irrespective of Ch and Ac, behaved as diluted solutions, with G" > G'. The relaxation exponent (n") was always higher than 0.5, confirming that these systems behaved as a viscoelastic liquid. This n" increased with Ch, but it was insensitive to Ac, being slightly higher at 45 °C.