Combined drying of Nopal pads ( Opuntia ficus‐indica ): Optimization of osmotic dehydration as a pretreatment before hot air drying

Abstract

The aim of this work was to optimize the osmotic dehydration (OD) as a pretreatment before hot air drying (HAD) in Nopal pads. A Box–Behnken experimental design was used to optimize the OD conditions with respect to physicochemical and chromatic parameters, and mechanical properties of Nopal pads. Factors studied were: Three concentrations of sucrose (30, 40, and 50°Brix), calcium lactate (1, 2, and3%), and immersion time (1.5, 2.5, and 3.5 hr). Results showed that sucrose concentration and immersion time were the variables with higher influence. Quality properties mentioned before and the final mineral content of the dried samples (at 60°C for 48 hr) were analyzed. The combined drying (OD + HAD) reduced the moisture content in the range of 23% to 30% compared to HAD alone. It was found that the optimization of OD allowed preserving the quality properties, being a good alternative to give an added value for dried Nopal pads. Practical applications Nopal has important bioactive properties for both humans and animal diets, since it is a rich source of vitamins, minerals, and fibers. However, the main problem of its production is that post harvesting waste is greater than 50%. For this reason, there is a great interest to study inexpensive preservation methods that allow keeping the main attributes of processed fruits. The osmotic dehydration (OD) and the hot air drying (HAD) are two simple and inexpensive techniques which can be applied by both the food industry and small‐scale food producers. In the present study, the optimization of OD as a pretreatment before HAD was a reliable tool to preserve the quality properties of Nopal pads.

Review: Effect of the combined application of edible coatings and osmotic dehydration on the performance of the process and the quality of pear cubes

“…Total colour difference Total colour difference of the fresh and osmodehydrated samples was determined using a colorimeter (Konica Minolta Chromameter, Model CR 400/410, Japan) with illuminant D65, 2°observer angle and calibrated using a standard white tile. The system selected was CIE L* a* b* (Rodriguez et al, 2019). Twentyfour pear cubes were measured for each treatment.…”

The influence of the pretreatment of garlic (Allium sativum L.) and tomato (Solanum lycopersicum L.) osmotic solution on physical properties of the material

“…According to literature data, fresh tomato juice has a pH in the range of 4.05 to 4.65 (Ağçam et al, 2018), however, commercial juices were also reported to have a pH of 3.6 ± 0.1 (Zhu et al, 2018) which is in line with the juice used in the study. Research conducted by Rodrigues et al showed that pretreatment of the OS, carried out to optimize the OD process favorably affects the quality of samples that are further dried after OD (Rodriguez et al, 2019). Therefore, the pH of tomato juice was gradually lowered in this study from pH = 3.5 ± 0.1 to pH = 2.0 ± 0.1 in OSs before OD to investigate the effect of pH on the OD kinetics.…”

“…showed that pretreatment of the OS, carried out to optimize the OD process favorably affects the quality of samples that are further dried after OD (Rodriguez et al, 2019). Therefore, the pH of tomato juice was gradually lowered in this study from pH = 3.5 ± 0.1 to pH = 2.0 ± 0.1 in OSs before OD to investigate the effect of pH on the OD kinetics.…”

Convective drying and quality attributes of osmo-dehydrated banana slices using coconut sugar and sucrose as osmotic agents

“…Furthermore, the dry product has advantages such as smaller volume, ease of distribution, year-round availability, and low perishability (Braga et al, 2009). Although there are several ways to dry food, drying with heated air is the most traditional method (Rodriguez et al, 2019).…”