However, the rate of mass transfer during osmotic dehydration is generally low and depends on the structure of the raw materials and the soaking conditions. The objective of this study was to investigate the effect of PVOD on mass transfer and antioxidant replacement in model foods, fresh and dried mango cubes. PVOD is vacuum osmotic dehydration; OD is osmotic dehydration; Fortified are the fortified substances of mango (gallic acid, ascorbic acid, calcium lactate); AD is air dried.
Untreated is control; PVOD is pulsed vacuum osmotic dehydration; OD is osmotic dehydration; Enriched are mango-enriched substances (gallic acid, ascorbic acid, calcium lactate); AD are air-dried mango samples; FD are freeze-dried mango samples.
INTRODUCTION
- Background
- Objectives of the research
- Expected outcomes
- Research hypotheses
- Scope of the research
- Definitions
Moreover, application of PVOD during phenolic supplementation in apple, banana and potato increased the phenolics in OD solution. After drying, PVOD significantly preserved the phenolic content and antioxidant capacity in the obtained products (Rózek et al., 2010b). Here, process conditions of PVOD for development of functional dried fruits were investigated and optimized.
Nutraceuticals are defined as foods or parts of foods that provide medical or health benefits (Penner et al., 2005).
LITERATURE REVIEW
Osmotic dehydration
- Principles
- Mass transfer in osmotic process
- Factors affecting the osmotic dehydration process
- Osmotic solution
- Concentration of osmotic solution
- Properties of solute used in osmosis
- Process temperature
- Agitation
- Solution to sample ratio
- Process duration
- Size and shape of food materials
- The advantages of osmotic dehydration (Yadav & Singh, 2014)
- Application of osmotic dehydration
Three types of solutions are commonly used to pretreat food material in the osmotic dehydration process as (1) isotonic solution, where the solute in the osmotic solution has the same solute as that within the cell membrane of food material, (2) hypotonic solution which is a has lower solute content than the solution inside the cell membrane, and (3) hypertonic solution which has a higher solute content than the solution inside the cell membrane (Zhao & Xie, 2004). The physicochemical properties of solutes such as molecular weight and water solubility are of great importance in the osmotic dehydration process (Rahman, 2005), affecting the mass transfer rate, physicochemical properties and sensory properties of osmotically dehydrated products. Methods to increase the rate of mass transfer in the osmotic dehydration process include agitation, although this method may cause breakdown of the food sample.
Water loss and solute gain increased with an increase in immersion time due to reduced viscosity in the osmotic solution and swelling of the cell membrane.
Vacuum impregnation
- Principles
- Osmotic dehydration treatment and vacuum impregnation
- Factors affecting the vacuum impregnation process
- Vacuum pressure and time
- Type of solutions
- Process temperature
- Solution to food material ratio
- Agitation of an impregnation solution
- Characteristics of food structure
- Applications of vacuum impregnation in food processing
- Pre-dehydration of fruits and vegetables
- Pretreatment before freezing
- Development of nutritionally fortified fruits and vegetables
- VI for developing minimally-processed fruits and vegetables
In general, water loss increased with an increase in process temperature, but with no effect on the amount of dissolved solids (Kaymak-Ertekin & Sultanoglu, 2000; Sereno et al., 2001). The application of agitation in the VI process affects mass transfer kinetics, such as water loss and solute increase in food samples, as reported by Panagiotou et al., 1998). Applications of vacuum impregnation in food processing include the pretreatment of food materials to improve product quality in freezing and drying processes, and modifying the physicochemical properties of the final products (Fito & Chiralt, 2000; Fito et al., 2001a; Fito et al ., 2001b).
Pretreatment with vacuum saturation is considered a useful way to improve the quality of frozen fruits and vegetables, such as improving texture quality, reducing droplet loss and energy consumption during the freezing process (Martínez-Monzó et al. , 1998; Sormani et al., 1999; Maestrelli et al., 2001).
Nutraceuticals
VI is applied to the pre-treatment of food materials before drying by reducing the water content, resulting in energy savings. The incorporation of substances in food structures such as antimicrobial, antioxidant and anti-caking agents in the porous structure of food results in the improvement of product quality (Sapers et al., 1990; . Fito, 1994; Barat et al., 2001; Torreggiani et al. ., 2001). VI has been studied to introduce many desirable substances into the porous structure of food, easily modifying their original composition as a tool for the development of new products such as dried apple enriched with probiotics (Betoret et al., 2003), calcium and iron-fortified apple slices (Barrera et al., 2004; . Barrera et al., 2009), fruit and vegetables supplemented with grape phenolics (Rózek et al., 2010b), fruit (sweet cherry, mango and blueberry ) enriched with ingredients (nutraceutical) Jacob & Paliyath, 2012) and apple foods rich in flavonoids (Betoret et al., 2012).
This technique can impregnate many substances into the porous structures of fruit or vegetable tissues such as organic acid, antioxidant agents, minerals and vitamins, resulting in increased stability and quality, as well as improved shelf life of the final product through partial removal of water. (Zhao & Xie, 2004).
Gallic acid
Ascorbic acid
Food drying
- Product quality during drying
- Physical and chemical properties
- Nutritional value
- Antioxidants
- Equipment
- Freeze dryer
The quality characteristics of dried foods can be divided into four parts, including physical, chemical, biological and nutritional (Sablani, 2006). The rate of rehydration is one of the most important variables affecting the quality of dried foods. The shrinkage of food during drying may be due to water removal from the food structure, after which the outer skin structure collapses, resulting in cases hardening at the skin surface of dried food.
Color changes in dried food during drying due to Maillard reaction and enzymatic browning affect the appearance of the product and the level of consumer acceptance.
Mango (Mangifera indica. L)
Porous dried particles with a lower density than the original food. - Smell and taste change. - Preservation of smell and taste. Reduced nutritional value - Retention of nutritional value - Economic costs - High costs, up to four times higher. As mango is a seasonal fruit, processing should increasingly be considered as a complementary alternative to reduce post-harvest losses and add value to final products.
Thus, a considerable amount of quantitative data is needed to assess the natural variations to select superior mango genotypes with improved nutritional quality and processing characteristics (Liu et al., 2013).
Related research
- Application of the pulsed vacuum osmotic dehydration (PVOD) process
- Application of vacuum impregnation to enrich fruits and vegetables
In recent studies, PVOD was used to modify the properties of foods in terms of nutritional, sensory, shelf life and physicochemical and appearance properties of foods (Barat et al., 2001; Mújica-Paz et al., 2003b; Schulze et al. found , that VI could significantly infuse quercetin derivatives into the total quercetin content and quercetin glycoside composition of apple slices dried by freeze-drying, which could preserve their stability during storage for 12 months. After drying, PVOD could significantly preserve phenolic content and antioxidant capacity in obtained products (Rózek et al ., 2010b) VI has been considered a useful way to introduce desirable solutes into the porous structure of foods and conveniently change their original composition as a tool for the development of new products such as calcium and iron enriched apple slices (Barrera et al., 2009; Barrera et al., 2004) and grapefruit, pineapple supplemented with calcium lactate and ascorbic acid (Silva et al.,.
Rózek et al., 2010b), fruit (sweet cherry, mango and blueberry) enriched with nutritional components (Jacob & Paliyath, 2012), mango supplemented with calcium lactate (Torres et al., 2006), grapefruit and apple snack rich in flavonoids (Betoret et al. al., 2012).
METHODOLOGY
- Experimental plan
- Instruments and equipment
- Materials
- Chemicals and reagents
- Methods
- Effect of process conditions on mass transfer, volume and porosity of the
- Impact of PVOD process conditions on nutraceuticals and health
- Impact of drying methods on ingredient stability
- Statistical analysis
Vacuum pressure was applied at 150 mbar for 10–30 min using a vacuum pump (Gast model DOA-P504-BN Labmodel, Germany), then the samples were recovered in atmospheric pressure for 180 min (Moraga et al., 2009) . Moisture contents of the samples were analyzed according to the standard method (AOAC, 2000) in an oven at 105 oC. 4) Bulk and solid-liquid densities and porosity followed (Nieto et al., 2004). The samples were weighed (~1.5–2.5 g) with a digital balance and placed in a glass pycnometer (fill volume 100 ml).
Samples were immersed (3 min) in a 1% w/v calcium chloride solution as a firmness stabilizer with 1% w/v ascorbic acid and 1% w/v citric acid as anti-tanning agents (Robles-Sánchez et al., 2009 ). Vacuum pressure was applied at 150 mbar using a vacuum pump (Gast model DOA-P504-BN Labmodel, Germany), then the samples were placed under atmospheric pressure for 180 min (Moraga et al., 2009). The impregnated samples were extracted using the method of (Liu et al., 2013) with some modifications.
Ascorbic acid and sucrose content of the samples were extracted following the procedures of Liu et al. Briefly, 20 grams of untreated or impregnated samples were mixed in 100 mL of 2.5% w/v metaphosphoric acid solution in a conical flask covered with aluminum foil. Two grams of untreated or impregnated samples were mixed in 10 ml of the mixed solution with a 2:1 (% w/w) nitric acid/perchloric acid ratio in a glass digestion tube.
Concentrations of calcium in samples were analyzed with an inductively coupled plasma optical emission spectrometer (ICP-OES Optima 8000 DV, Perkin-Elmer, Wellesley, MA, USA). Food and Drug Administration (1998). Samples were weighed (25 grams) and then added to 225 ml of 1% peptone water solution to give a 10-1 dilution.
RERULTS AND DISCUSSION
Results and Discussion
- Optimization
- The effect of PVOD, OD and solution components on the mass transfer
This is due to the application of vacuum pressure conditions, which causes the gas to be in the pores of the agar gel. Osmotic dehydration techniques and osmotic agents significantly affected the SG of impregnated mango cubes (Table 29). Weight loss (WR) indicates the content of water loss in food materials during the osmotic dehydration process.
Osmotic dehydration techniques and osmotic agents significantly affected weight reduction (WR) of saturated mango cubes (P 0.05). Osmotic dehydration techniques and osmotic agents were significantly affected by WL of saturated food cube models (P 0.05). Osmotic dehydration techniques and osmotic agents significantly affected the SG of saturated model food cubes (Table 30).
In the present study, the osmotic dehydration techniques and osmotic agents significantly affected the WL/SG ratio of the impregnated model food cubes (Table 30). The results showed that color values of the impregnated mango cubes were significantly affected by the osmotic dehydration techniques and osmotic agents (P 0.05). After completion of the osmotic dehydration process, lightness (L*) and b* values of the impregnated mango cubes were reduced, while value was increased (Table 31).
The results showed that the osmotic dehydration methods and osmotic agents significantly affected the volume change of the impregnated mango cubes (P = 0.05). It has previously been shown that the total soluble solids of the impregnated mango affects the osmotic dehydration time (Zou et al., 2013). This leads to the removal of the gas in the agar gel structure (Corrêa et al., 2010).
The results showed that the osmotic dehydration techniques and osmotic solution significantly affected the total phenolic content and DPPH radical scavenging activity of the impregnated model food cubes (P 0.05).
CONCLUSION AND RECOMMENDATION
Conclusions
- Part I : Study on process variables of mass transfer, volume, porosity of
- Part II: Study on impact of PVOD process conditions on nutraceuticals
- Part III : Study on impact of drying methods on ingredient stability
Recommendations
Effect of osmotic solution concentration, temperature and vacuum impregnation pretreatment on osmotic dehydration kinetics of apple slices. Ca2+ and Fe2+ influence on the osmotic dehydration kinetics of apple slices (var. Granny Smith). Pulsed vacuum osmotic dehydration of beetroot, carrot and eggplant slices: Effect of vacuum pressure on the quality parameters.
The influence of physical properties of selected plant materials on the process of osmotic dehydration. Effect of vacuum impregnation with calcium lactate on the osmotic dehydration kinetics and quality of osmohydrated grapefruit. Evaluation of mass transfer coefficients and volumetric loss during osmotic dehydration of apple using sucrose.
Impregnation and osmotic dehydration of some fruits: Effect of the vacuum pressure and syrup concentration. Osmotic dehydration of apple: Influence of sugar and water activity on tissue structure, rheological properties and water mobility. Effect of syrup concentration, temperature and sample geometry on equilibrium distribution coefficients during osmotic dehydration of mango.
Mass transfer coefficients during osmotic dehydration of apple in single and combined aqueous solutions of sugar and salt. Diffusion mechanisms during osmotic dehydration of Granny Smith apples subjected to a moderate electric field. Correction of effective moisture and sucrose diffusivities for shrinkage during osmotic dehydration of apple in sucrose solution.
Optimization of some process variables in the mass transfer kinetics of osmotic dehydration of pineapple slices.
