High pressure impregnation (HPI) of apple cubes: Effect of pressure variables and carrier medium

Osmotic dehydration: More than water loss and solid gain

The immersion of food in a hypertonic solution results in an osmotic dehydration process (OD) with the loss of water (WL) from the food to the solution and the gain of solids from the solution (SG) by the food. For this reason, OD is commonly used to produce semi-dehydrated or enriched foods by incorporation. Although the most of OD studies are focused on the WL and SG processes, many publications addresses the physicochemical and nutritional changes resulting from OD in the food matrix and in the osmotic solution. Such changes must be handled in order to improve the quality of the product. This work is a compilation of publications with this approach.

Effects of combined application of high-pressure processing and active coatings on phenolic compounds and microbiological and physicochemical quality of apple cubes

BACKGROUND

In recent years the use of high-pressure processing (HPP) of fruit products has steadily increased due to its antimicrobial effectiveness and the retention of nutritional and quality attributes compared to conventional thermal technologies. Edible coatings are already being used to enhance the quality of minimally processed fruits. Thus, apple cubes (AC) and alginate-vanillin-coated apple cubes (AVAC) were subjected to HPP (400 MPa/5 min/35 °C). The microbiological and physicochemical parameters were evaluated and the bioactive compounds were monitored before and after HPP of apple cubes. Also, an in vitro gastrointestinal digestion (GID) was conducted.

RESULTS

HPP left L. monocytogenes counts below the detection limit (2 log UFC g^-1 ), regardless of the presence of coating. For E. coli, HPP + active coating showed a synergism affording the greatest reduction (>5 log) for AVAC-HPP. Firmness was maintained in AVAC-HPP samples, while AC-HPP samples suffered reductions of 35%. Colour attributes were also better retained in AVAC-HPP samples. In general, HPP led to a decrease in phenolic compounds. Regarding the effects of GID, vanillin-based active coating exerted a protective effect on some phenolics. Thus, p-coumaroylquinic acid concentration was maintained for AVAC and AVAC-HPP during GID. Epigallocatechin, the compound with the highest concentration in apple cubes, increased for AVAC (106%) and AVAC-HPP (57%). Also, phloridzin concentration increased for AVAC-HPP (17%). At the end of GID, procyanidin B1 and epigallocatechin were the main phenolic compounds for all samples, AVAC showing the highest concentration.

CONCLUSIONS

This work demonstrates that the combined application of HPP and active coatings on apple cubes could be used to obtain a safe and good-quality product. © 2021 Society of Chemical Industry.

Effect of high pressure impregnation on micronutrient transfer in rice

Rice, consumed by most people across the world, serves as a great mode for carrying nutrients. The processed, starch-rich white rice is mostly devoid of nutrients. High-pressure processing (HPP) is a technology known to produce cold gelatinizing effects in starch. This work shows the application of HPP in fortification of two types of white rice through high pressure gelatinization. The rice grains were impregnated with vitamin B₁, calcium, and zinc. HPP treatment was carried out at the temperatures of 50 °C and 70 °C for up to 20 min. The samples were analysed for thiamine using the fluorometric method and minerals using ICP-MS. Results showed that the transfer of nutrients increases with treatment temperature and time, producing high level of nutrient uptake. HPP-fortified rice also showed stability after storage of two months. The moderate-temperature HPP has a great potential to be used as a method to produce a ready-to-eat variety of rice.

A Review on the Effect of High Pressure Processing (HPP) on Gelatinization and Infusion of Nutrients

High pressure processing (HPP) is a novel technology that involves subjecting foods to high hydrostatic pressures of the order of 100-600 MPa. This technology has been proven successful for inactivation of numerous microorganisms, spores and enzymes in foods, leading to increased shelf life. HPP is not limited to cold pasteurization, but has many other applications. The focus of this paper is to explore other applications of HPP, such as gelatinization, forced water absorption and infusion of nutrients. The use of high pressure in producing cold gelatinizing effects, imparting unique properties to food and improving food quality will be also discussed, highlighting the latest published studies and the innovative methods adopted.