Osmotic dehydration (OD) is a process of soaking products in an aqueous solution containing salt or sugar, which is normally applied to fruits and vegetables. The combination of OD pretreatment with freezing, or osmotic dehydrofreezing (ODF), is a novel technology to shorten the freezing process and prolong the preservation of fruits and vegetables. However, the effectiveness of ODF is affected by process parameters and nature of the product, thus information on freezing characteristics and quality of osmotically dehydrated frozen fruits and vegetables is useful to the food industry. This review intends to provide an overview of the effects of OD pretreatment on freezing characteristics such as freezing rate, thermal properties, and quality of frozen fruits and vegetables. Fundamentals of ODF technology, including significance of OD to freezing, and mechanism and factors affecting ODF are summarized. In addition, hurdle technologies comprising of ODF and other innovative nonthermal techniques, such as ultrasound and pulsed electric field (PEF) are presented, and future trends of the combined technology are briefly discussed. ODF can accelerate the freezing process and enhance the quality of osmotically dehydrated frozen fruits and vegetables. The novel ultrasound and PEF techniques, which can provide cryoprotection from in situ interference, were proposed for the production of product with many‐functional characteristics, by incorporating bioactive compounds like plants sterols, probiotics, and dietary fibers, into the matrix of cellular tissues during ODF process. However, these techniques can enhance the performance of the ODF to promote fast freezing, produce small ice crystals, and raise glass transition temperature of cellular tissues. The future trends of ODF technology should mainly focus on controlling the mass and heat transfer processes, improving quality stability during glassy state storage condition and development of product with many‐functional characteristics. Practical Applications Fruits and vegetables are subject to freezing damage, particularly tissue softening and drip loss when thawing, thus reducing their quality and market value. OD pretreatments to freezing or ODF has great potentials in preservation of fruits and vegetables, with the advantage of minimum quality loss due to the reduction in freezing loads. Currently, innovative studies have been carried out on the combined use of OD pretreatments and emerging freezing techniques to improve the freezing process, achieve better quality with extended shelf life, and produce products with many‐functional characteristics. However, the findings presented in this review work can provide detail insights on the quality of fruits and vegetables that were frozen by ODF and give some guidance for further developments of ODF technology.

Background Packaging of locust beans is done to prevent deterioration and promote its shelf-life. This research was carried out to develop and evaluate a cocoyam starch-banana peels nanocomposite film for locust beans packaging. The film was prepared by gelatinizing a mixture of 0.36 g banana peels nanoparticles (~ 1.14–1.64 nm), 18 g cocoyam starch, and 18 ml glycerol in 300 ml distilled water at 90 °C. The thermal, structural, mechanical and barrier properties of the film were determined using standard procedures. A 100 g of the locust beans condiment was packaged using the film and compared with packaging in a low-density polyethylene (LDPE) at 5.16–7.58 pH and 16.67–11.50% moisture ranges. Results Results indicate approx. 3% weight loss with an increase in temperature (≤ 250 °C). The heat of decomposition in the process was 4.64 J/g, which depended on the transition temperature. Also, the film has high stiffness and creep along the line of topography in the atomic force imaging. The material permeates more to CO2 (27%) and H2 (67%) but has a low O2 (4%) and N2 (1%) gas permeabilities. The size of particles in the film was in the range of 3.52–3.92 nm, which is distributed across its matrix to create the pores needed to balance the gases in the micro-atmosphere. The microbial load of the locust beans decreased with pH and increased with moisture, but this was generally lower compared to those packaged in the LDPE at p < 0.05. Conclusions The film was a better packaging material than the LDPE since it recorded lower counts of the microbes throughout the storage. Thus, the nanocomposite film was effective in controlling the microbial growth of the locust beans irrespective of the sample moisture and pH over the 30 days packaging duration.

The research investigated physical properties of baobab seeds to determine suitable equipment for the processing of its seeds. Pods of baobab used in the study were collected at a local farm in Ilorin, North Central Nigeria. Physical properties of the samples, such as moisture contents, mass, axial dimensions, shape indices, true and bulk densities, porosity, angle of repose and surface area were determined. The results showed that physical properties of baobab seeds were stable for moisture content, ranging between 12 to 18% dry mass (dm). The 100 seed mass (g) and geometric mean diameter increased from 0.60 g to 0.62 g and 10.12 to 10.27 mm respectively, in the moisture range of 12 to 18% dm. Other studied ranges of physical properties ranges included: average length (12.22 to 12.63 mm), width (10.10 to 10.28 mm), thickness (8.23 to 8.42 mm,), sphericity, (81.23 to 82.56 mm), surface area (319.42 to 332.53 mm2), 50 seed mass (0.60 and 0.62 g), and 1000 seed mass (12 and 12.4 g) within the moisture content range of 12 to 18% dm. The angle of repose of baobab seeds decreased with an increase in moisture content. The maximum value of 29.18o was obtained at 14% moisture content while a minimum value of 24.42o was obtained at 18% moisture. Moisture content had a significant effect on coefficient of friction of baobab seeds on glass, stainless steel, plywood and rubber. In the same moisture range (12-18%), the static coefficient of friction for baobab seeds ranged from 0-739 to 0-905 on stainless steel, 0-960 to 1-190 on galvanized steel, 0-812 to 1-055 on plywood and 0-496 to 0-950 on glass. The least coefficient of friction values were recorded on stainless steel and glass which implies that baobab seeds will move with lower resistance on these surfaces in post-harvest handling. On the other hand, the resistance will be higher on plywood and glass. The data obtained will serve as guide for agricultural and food engineers, food processors and technicians involved in design and construction of post-harvest equipment used for separating, cleaning, milling and other production processes, to which baobab seeds are subjected.