EFFECT OF OSMOTIC AGENT ON OSMOTIC DEHYDRATION OF FRUITSN.M. Panagiotou , V.T. Karathanos & Z.B. Maroulis. Drying Technology: An International Journal, 17:1-2, 175-189(2007)

Presented by:Pragati Singham

M.Tech (FPEM)212011

• Title:- Effect of osmotic agent on osmotic dehydration of fruits

• Author :- N.M. Panagiotou , V.T. Karathanos & Z.B. Maroulis

• Published:- 17:1-2, 175-189(2007)

• Journal:- Drying Technology: An International Journal• Impact factor:- 2.084 = Cites to recent articles No. of recent articles

CONTENTS

1. Why osmodehydration ??2. Principle 3. Abstract4. Introduction5. Materials and methods6. Results & discussion7. Conclusion8. References

Why Osmodehydration ??

Dehydration

1. Rehydration is needed

2. Sensorial properties are

affected.

3. Loss of flavor

4. Huge nutrients loss.

5. Chance of physical

contamination

Osmodehydration

1. Rehydration is not needed

2. Sensorial properties are very

good

3. Retention of fresh fruit

flavors.

4. Retention of nutrients.

5. No chance of contaminationHence, for improved quality & Ready To Eat products

osmodehydration is the best choice!!!

DEHYDRATED FRUITS

OSMOTICALLY DEHYDRATED FRUITS

PRINCIPLE OF OSMODEHYDRATION

OSMOSIS

water ordilute solution

concentratedsolution

membrane

More water passes fromdilute to concentrated ...

...until concentrationsbecome equal

level riseslevel falls

• There are microscopic pores in the membrane.

• Molecules below a certain size can diffuse through the pores.

•Water molecules can easily diffuse through the pores.

In the next slides represents a water molecule

and represents a sugar molecule

membranewater sugar solution

There are as many water molecules on the right as there are on the left but many of them are attached to sugar molecules and are not free to move.

Because there are more freely moving water molecules onthe left, more diffuse through the pores of the membrane from left to right than from right to left.

Next slide

RESEARCH PAPER

EFFECT OF OSMOTIC AGENT ON OSMOTIC DEHYDRATION OF FRUITS

(N.M. Panagiotou , V.T. Karathanos & Z.B. Maroulis)

ABSTRACT

• Investigated about mass transfer phenomenon during osmotic dehydration.

• Variable parameters- – Temperature – Samples size – Osmotic agent concentration– Time

• Osmotic agents with low molecular weight leads to higher water loss & solids uptake

INTRODUCTION• Process of water removal by immersion of

water containing cellular solid in a concentrated aqueous solution.

(Toreggiani et al., 1987; Beristain et al., 1990; Rastogi and Raghavarao, 1994; Lazarides and Mavroudis, 1996).

• Two major simultaneous counter current flows-– Water diffusion into the solution– Solute diffusion into food.

Leaching out of food’s tissue own solute(Rastogi and Raghavarao (1994),)

• Driving force -osmotic pressure

Pathway in long term osmotic dehydration process (adapted from Fito and Chiralt,2003).

• Main objectives of this study were-

– To investigate the effect of osmotic agent on osmodehydration of fruits

– To develop a mathematical model to incorporate the effect of osmotic agent characteristics.

MATERIALS & METHODS

• Three fruits:-– apple, banana, kiwi

• Osmotic concentration agents-– D (+) Glucose (mol. wt. 180.2)– D (+) Sucrose (mol. wt. 342.3)

• Concentration levels- 20%, 40%, 60% (glucose) 30%, 40%,50% (sucrose)

SAMPLE PREPARATION

S.No Fruit Size 1(mm)

Size 2(mm)

Size 3(mm)

Size 4(mm)

Size 5(mm)

Length/Diameter

1. Apple 4 8 12 16 20 40mm long

2. Banana 4 8 12 16 20 2.2cm dia

3. Kiwi 4 8 12 16 20 4.5cm dia

All the fruits of all sizes were immersed into the glucose & sucrose solution of variable concentrations.

RESULTS & DISCUSSIONS

• Water loss & Solids gain• Effect of-– Immersion time – Process temperature– Molecular weight– Rate constant– Concentration

Fig.1. Effect of solute type & concentration on water loss

WATER LOSS

Fig.2 Effect of solute type & concentration on water loss

Effect of time on textural properties of kiwi

Fig.3.(a) Effect of osmotic agent molecular weight on equilibrium water loss

Fig.3.(b) Effect of osmotic agent molecular weight on rate constant of water loss

Fig.4.Effect of solute type & concentration on solid gain

SOLIDS GAIN

Fig.5. Effect of solute type & concentration on solid gain

Fig.6.(a) Effect of osmotic agent molecular weight on equilibrium solids gain

Fig.6.(b) Effect of osmotic agent molecular weight on rate constant of solids gain

MATHEMATICAL MODELING

Then, Acc. to first order kinetics

Let,WL= water lossSG= solids gain

CONCLUSION

• Glucose – more effective in water loss & solids gain.

• Molecular weight of the 1/ α rate of water loss & Solids

osmoactive substances was gain

• Water loss by 40 % glucose soln. was higher than 50 % sucrose soln.

MAJOR DRAWBACKS FOR COMMERCIALIZATION

• It does not remove whole water, hence it can be mainly used as pre treatment for-– Freezing (Ponting, 1973), – Air drying (Nanjundaswamy et al., 1978)– vacuum drying (Dixon and Jen, 1977), – Freeze drying (Hawks and Flink, 1978)– sun drying, pasteurising or acidification and coating by

edible surface layers (Flink, 1979).

• Counter current diffusion of osmoactive substances.

REFERENCES• Lewicki P. and Lenart A. Osmotic Dehydration of Fruits and

Vegetables. • Majumdar A. S. , Handbook of industrial drying. • Rastogi, N.K.; Raghavarao, K.S.M.S. (2004). Mass Transfer During

Osmotic Dehydration: Determination of Moisture and Solute Diffusion Coefficients from Concentration Profiles.. Food and Bioproducts Processing vol. 82 ,. p. 44-48

• Shi J. & Le Maguer M. (2002) Osmotic dehydration of foods: mass transfer and modeling aspects. Food reviews International Vol. 18, No. 4, pp. 305–335.

• Tortoe C (2010). A review of osmodehydration in food industry. African Journal of Food Science Vol. 4(6), pp. 303 – 324.

• http://www.icar.org.in/horticulture.htm• http://www.epa.gov/ttnchie1/ap42/ch09/final/c9s08-2.pdf• http://mofpi.nic.in/images/pdf/fruits/dehydration_of_fruits.pdf• http://www.barc.gov.in/technologies/osmotic.html

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