Structure influence on mechanical and acoustic properties of freeze-dried gels obtained with the use of hydrocolloids

The effect of apple pomace powder and calcium ions on selected physicochemical properties of freeze-dried carrot-orange-ginger snacks

BACKGROUND

This study aimed to determine the effect of various amounts of dried apple pomace (AP) powder and calcium ions on selected physicochemical properties of restructured freeze-dried snacks in comparison with products obtained with low-methoxyl pectin (LMP). The material was prepared using frozen carrot, orange concentrate, ginger, water, and various concentrations of AP (1, 3, 5%) and calcium lactate (0, 0.01, 0.05%). The reference samples were without additives, and with 0.5 or 1.5% of LMP combined with 0.01% of calcium lactate.

RESULTS

The material was studied in terms of water content and activity, hygroscopic properties, structure, texture, color, and polyphenol content (TPC), and antioxidant activity. The addition of AP resulted in reducing water activity and porosity. As a consequence of the increasing density of the structure, the reduction of hygroscopic properties by up to 16% followed the increasing amount of AP. Apple pomace and calcium ions strengthened the structure. The addition of 3% and 5% of AP gave a hardening effect close to or better than 0.5% LMP. Because of the pigment dilution, LMP caused significantly greater total color change than AP. The incorporation of AP also increased TPC and enhanced antioxidant activity in comparison with the reference materials by up to 18%.

CONCLUSION

The results showed that dried AP powder can be applied successfully as an additive enhancing stability, texture and bioactive compound content, thus fortifying the physicochemical properties of restructured freeze-dried fruit and vegetable snacks. © 2023 Society of Chemical Industry.

The Effect of Composition, Pre-Treatment on the Mechanical and Acoustic Properties of Apple Gels and Freeze-Dried Materials

This study aimed to determine the effect of the addition of apple juice concentrate (AJC) on the properties of agar gel and dried materials. Agar gels with the addition of apple juice concentrate in the range of 5–20% were prepared with or without the addition of maltodextrin. The gels were also soaked in the solution of AJC. The water content, water activity, densities, some mechanical and acoustic descriptors of gels, and the freeze-dried gels were analysed. The porosity and shrinkage of dried products were also investigated. The addition of AJC significantly changed mechanical and acoustic properties of gels. The hardness of gels decreased with a higher addition of concentrate. Dried samples with a lower concentration of sugars (the lower addition of AJC) were characterised by lower shrinkage and higher porosity, as well as crispness and glass transition temperature. The investigated mechanical and acoustic properties of dried gels showed the addition of apple concentrate at the level of 5% to agar solution was optimal.

Effect of Addition of Chokeberry Juice Concentrate and Foaming Agent on the Physical Properties of Agar Gel

This study aimed to determine the effect of the addition of chokeberry juice concentrate (CJC) and foaming agent (egg albumin) with different percentages on the selected physical properties of agar gel. The agar gels with the addition of 5, 10, and 20% concentrations of chokeberry juice concentrate and with fructose addition were prepared. In addition, the foamed gels with different concentrations of egg albumin (in the range 0.5–2.0%) and CJC were produced. The water content, colour, density, hold-up and some mechanical and TPA (Texture Profile Analysis) descriptors as well some structural and acoustic emission parameters of non-aerated and foamed gels were analysed. The addition of CJC changed the colour of agar gel with fructose, the attractive appearance of the aerated gel was also linked with the addition of concentrate. The addition of 20% of CJC and foaming agent created samples with very low hardness, cohesiveness, and gumminess, and the structure of the aerated samples was characterised by the larger bubble diameter and the wider distribution of their size. The more promising texture and structure properties were obtained for samples with aerated gels with 5 and 10% addition of chokeberry juice concentrate.

Influence of Pear Variety and Drying Methods on the Quality of Dried Fruit

In this study, the impacts of two different pear cultivars, “Conference” and “Alexander Lucas”, on the kinetics and the final quality of samples dried by convection (CD) and microwave-convection (MCD) methods, were investigated. The quality of dried material was evaluated by the analysis of water activity, porosity, color, acoustic emission (AE) and mechanical and sensory properties. The required drying time to obtain 0.2 kg H₂O/kg dry solid (d.s.) was longer for “Conference” than “Alexander Lucas” and was 20 min by CD and 5 min by MCD. The pear cultivar, in conjunction with the drying method (CD or MCD), affected the number of AE events and the work of breaking. The CD pear of the “Conference” cultivar was characterized by higher force, higher breaking work and stronger AE relative to the CD pear of the “Alexander Lucas” cultivar. There were no differences in taste or overall quality, but the hardness was higher for the CD “Conference” pear. A principal component analysis showed that panelists preferred dried fruit with good taste and overall quality but lower hardness. A positive correlation was found between the number of acoustic events and sensory hardness; thus, an acoustic method can be useful for effectively evaluating the texture of dried pears. These results show that the dried pear slices that generated fewer AE events upon breaking were perceived as better by the panelists.

Mucoadhesive Vaginal Discs based on Cyclodextrin and Surfactants for the Controlled Release of Antiretroviral Drugs to Prevent the Sexual Transmission of HIV

The strategies for developing vaginal microbicides to protect women against human immunodeficiency virus (HIV) sexual transmission are constantly changing. Although the initial dosage forms required daily administration to offer effective protection, the trend then moved towards sustained-release dosage forms that require less frequency of administration in order to improve women's compliance with the treatment. Nevertheless, another possible strategy is to design on-demand products that can be used in a coitally-dependent manner and only need to be administered immediately before intercourse to offer protection. Vaginal discs based on freeze-dried hydroxypropylmethyl cellulose gels have been developed for this purpose, containing two surfactants, i.e., sodium dodecyl sulphate and polysorbate 60, alone or in combination with 2-hydroxypropyl-β-cyclodextrin, to achieve a formulation capable of incorporating both hydrophilic and lipophilic drugs. Several studies have been carried out to evaluate how the inclusion of these substances modifies the structure of gels (viscosity and consistency studies) and the porosimetry of the freeze-dried discs (scanning electron microscopy micrographs, mechanical properties, swelling behaviour). The drug release and mucoadhesive properties of the discs have also been evaluated with a view to their clinical application. The systems combining sodium dodecyl sulphate and 2-hydroxypropyl-β-cyclodextrin were found to be adequate for the vaginal administration of both Tenofovir and Dapivirine and also offer excellent mucoadhesion to vaginal tissue; these discs could therefore be an interesting option for a coitally-dependent administration to protect women against HIV transmission.

Eating Habits and Sustainable Food Production in the Development of Innovative “Healthy” Snacks

In recent years, science about nutrition and food technology has grown enormously. These advances have provided information about the human body’s need for certain nutrients and the impact of human nutrition on quality of life and health. New technologies enable the production of many new products that meet the expectations of food consumers. To meet the challenges posed by consumers, food producers are developing new food products that are included in the next generation food. Changing nutritional trends force the food industry and technologists to look for innovative products that are not only ready for immediate consumption, but are also unique in terms of nutritional value and contain a minimum number of additives. Existing research trends are intended to develop innovative products, which can be considered a healthy snack that can help in the fight against obesity, especially among children. Such products are freeze-dried fruit or vegetable gels, fruit skins or edible films. The aim of the work is to present a review of the problem of increasing childhood obesity, the place of snacks in the daily diet and the possibility of replacing unhealthy, high-calorie snacks with alternative products with beneficial properties, in which balanced production is used. For example, the use of freeze-drying and the addition of only natural hydrocolloids provides an “clean label” healthy snack that is appreciated by conscious consumers.