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Water contamination is an issue requiring continuous remedy on daily basis because of the high demand for clean quality water. Scientists have proffered numerous ways of making this possible but the techniques involved is often difficult to replicate at small scale. For this reason, easier and cheaper techniques for contaminated water treatment are often sought after. One way of actualizing this is via nanotechnology, which involves the use of smaller particles (< 100 nm in size) to coagulate suspended substances and inhibit microbial growth in the targeted water. The mechanisms involved have been presented for zinc and magnetite nanoparticles in this write-up. This technology provides way of getting clean quality water for domestic, agricultural and industrial applications.

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.

Palm fruit oil extraction is a difficult task to undertake. Screw press technology offers a solution to its extraction. However, most screw press available requires high power input for effective operation, thus affecting cost. Therefore, there is a need for improvement in order to limit cost and increase extraction efficiency. This work focuses on development of a variable-pitch tapered-shaft (VATS)screw pressfor enhancing palm fruit oil extraction efficiency. The VATS screw press machine consists of three main components including the hopper, the steamer, and the pressing unit, and was operated at temperature of 90, 110 and 130°C, shaft speed of 30, 45, and 60 rpm and heating time of 10, 15, 20 minutes. The performance evaluation carried on the machine includes oil yield, extraction efficiency and extraction loss. The results showed that the average oil yield, extraction efficiency and extraction loss were 83.72, 97.73 and 2.37% respectively. Whereas, a higher machine efficiency of 94.45% was obtained at a temperature of 130°C, shaft speed of 60 rpm, and heating time of 15 minutes. It is hoped that the information on the design concept for VATS screw press for palm fruit oil extraction will be useful for the vegetable oil industry.