Evaluation of the Effects of Osmotic Dehydration Pretreatment at Low Pressure on Texture, Colour and Oil Absorption of Vacuum Fried Kiwi Slices

Subject Areas : Microbiology

Fateme Aghabozorgi Afge ¹ , Alireza Basiri ² , Abdol Reza Mohamadi Nafchi ³

1 - دانشجوی کارشناسی ارشد گروه مهندسی کشاورزی - علوم و صنایع غذایی، واحد دامغان، دانشگاه آزاد اسلامی، سمنان، ایران
2 - استادیار سازمان پژوهش های علمی و صنعتی ایران، پژوهشکده صنایع شیمیایی، تهران، ایران
3 - استادیار گروه علوم و صنایع غذایی، واحد دامغان، دانشگاه آزاد اسلامی، سمنان، ایران

Received: 2014-12-24 Accepted : 2014-12-24 Published : 2014-12-22

Keywords: Kiwi, Optimization, Response Surface, Vaccum Frying, Vaccum Osmotic Dehydration,

Abstract :

Introduction: Vacuum osmotic dehydration is one of the methods of preservation of fruits and vegetable. The aim of this work is the evaluation of the effects of variables in osmotic dehydration process (ambient pressure, contact time of product and solution, concentration and temperature of osmotic solution) on the quality factors of product (colour changes, texture, oil uptake) and finally achieving the optimum process conditions. Materials and Methods: A laboratory scale osmotic dehydration equipment including anaerobic jar, grid basket, vacuum pump, barometer and thermometer were used. The temperature range for osmotic solution (30 – 50° C), pressure (500-700 mbar), concentration of the osmotic solution (30- 50%) and contact time (60- 180 min) were employed. The test plans involving 31 tests were obtained by using response surface statistical models. The frying was carried out at 108ºC for 8 min and 320 mbar. Results: The optimum conditions of 48.71ºC for the osmotic solution temperature, 592.07 mbar for the pressure, 62.92 min for the time and 34.87% for the osmotic solution concentration were obtained. By applying the mentioned optimum conditions, the colour changes, oil absorption (g/100g) dry basis and texture (N/m) were found to be, 13.63, 14.82 and 2.78 respectively. Conclusion: The result showed that by increasing the osmotic solution temperature, texture rigidity is decreased and colour changes is increased. Colour changes, oil absorption and texture rigidity are decreased with increased osmotic solution concentration.