Osmotic dehydration of pineapple

One of the principal objectives of research on fruit conservation is the development of products with long shelf-lives and with sensorial and nutritional properties as similar as possible to those of fresh fruit. Evidently, these characteristics increase the probability of product acceptance by consumers. 

Osmotic dehydration is a technique that permits the reduction of the water content of food and consequently increases the shelf-life of the final product. The process consists of placing the raw material in contact with a very concentrated solution of an osmotic agent that is sensorially compatible with the product one wishes to obtain. This establishes an osmotic gradient that progressively takes water out of the treated fruit. 

A central composite design was employed to study how the dehydration of pineapple pieces depends on three factors contact time (1), process temperature (2) and concentration of osmotic solution (3). The relative loss of weight at the end of each run was taken as a measure of dehydration (Azeredo and Jardine, 2000). The results obtained are presented in Table 6A.2, where Xi, %2 and are coded values for the three factors. 

Fitting linear and quadratic models to the data in the table, we obtain the following equations  

It is clear that the quadratic model has a smaller lack of fit, and therefore is better than the linear model. Looking up the F-test table, you can confirm that the quadratic model does not present any evidence of lack of fit at the 95% confidence level. It explains 95.4% of the variation about the average and has MaSr/MSp = 20.69, which is more than six times the value of (at the same confidence level, of course). This 

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Looking more deeply into these ongoing studies, for example, the application of ultrahigh hydrostatic pressure, leads to significant changes in the tissue architecture. This resulted in increased mass transfer during the osmotic dehydration of pineapple and potato slices due to the combined effect... 

Central composite design for studying the osmotic dehydration of pineapple pieces... 

I. Beristain, E. Azuara, R. Cortes, and H.S. Garcia, Mass transfer during osmotic dehydration of pineapple rings, Int. J. Food Sci. TechnoL, 25 576 (1990). 

H.M.C. Azeredo and J.G. Jardine, Optimization of osmotic dehydration of pineapple applied to combined methods technology, Ciencia e Tecnologia de Alimentos, 20(1 ) 74... 

J.A. Pino, D. Castro, P. Fito, J. Barat, and F. Lopez, Multivariate statistical analysis of volatile compounds as a criterion for selecting technological parameters in the osmotic dehydration of pineapple, J. Food Qual., 22 653 (1999). 

D. Castro, O. Treto, P. Fito, G. Panades, M. Nunez, C. Fernandez, and J.M. Barat, Osmotic dehydration of pineapple under pulsed vacuum. Study of process variables, A/fmentana, 282 21 (1997). 

The effects of solution concentration, osmosis time, and the osmosis temperature were studied in the osmotic dehydration of pineapple in sucrose solution [58]. The solute diffusion was analyzed by Magee s model. The effect of sucrose concentration C on rate parameter K was given by power law regression equation as A = 4.15 x 10 at 20 C. 

Rastogi, N.K. and Niranjian, K. 1998. Enhanced mass transfer during osmotic dehydration of high pressure treated pineapple. J. Food Sci. 63, 508-511. 

Andreotti et al. [31] recognize a temperature of 43 C as the optimal for osmotic dehydration of cherries and pears in glucose or glucose-fructose syrup. They recommended a tan-peiature of 20 C for osmotic dehydration of apricots. Bananas were osmoticaUy dehydrated at 60°C [146] however, it was shown that optimal temperature was dependent on the concentration and pH of the osmotic solution [105]. Pineapple was dehydrated at 42 C-47°C [96] but application of vacuum and tonperature higher than 40°C resulted in loss of volatiles [112]. Osmotic dehydration of plums is done at 50°C [147,148], kiwifruit at 37°C, and peas at 50°C-70°C [124]. 

Baths have been used to apply ultrasound during the osmotic dehydration of apples in sugar solutions (Simal et al, 1998, 2006), cheese (Sanchez et al., 1999) or meat brining (Simal et al., 2006), and also to study its effects on mass transport kinetics. Ultrasound has also been applied in liquid-solid systems as a pretreatment prior to osmotic dehydration or hot-air drying of products such as banana (Fernandes and Rodrigues, 2007), pineapple (Fernandes et al., 2008) or malay apple (Oliveira et al., 2011). 

Navarro, P. and Corzo, O. 2001. Osmotic dehydration vacuum optimization for minimally processed pineapple. In Proceedings of the International Congress on Engineering and Food, ICEF 8 (J. Welti-Chanes, G.V. Barbosa-Canovas, and J.M. Aguilera, eds), Vol. 2, pp. 1309-1313. Technomic Publisher, Lancaster, PA. 

Rahman, M.D.S. and Lamb, J. 1991. Air drying behaviour of fresh and osmotically dehydrated pineapple. J. Food Process Engineer. 14, 163-171. 

Rastogi, N.K., Angersbach, A., Niranjan, K., and Knorr, D. 2000a. Rehydration kinetics of high pressure treated and osmotically dehydrated pineapple. Journal of Food Science 65 838-841. 

A. Paijoko, S.M. Rahman, K.A. Buckle, and C.O. Perera, Osmotic dehydration kinetics of pineapple wedges nsing palm sugar, LWT, 29 452 (1996). 

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