INTRODUCTION

Worldwide, part of the food produced by man for consumption is lost or wasted every year (Franco, 2016). In this sense, it has been calculated that in Europe and North America the losses have reached values of 95 to 115 kg.year^-4, and it has been identified that the causes of such losses and waste in middle-income and high-income countries are due to consumer behavior and poor coordination among supply chain actors (González, 2015). Other studies have shown that many foods, with good conditions to be consumed by people, have had losses and waste that have reached figures close to 1,300 tons per year (González, 2018).

Fruits are one of the products that are part of the extensive list of those who have suffered losses and waste. They constitute an essential food group for our health and well-being, especially for their contribution of fiber, vitamins, minerals and substances with antioxidant action (vitamin C, vitamin E, β-carotene, lycopene, lutein, flavonoids, anthocyanin, etc.) (Rodríguez & Sánchez, 2017). They are considered the most perishable food, and the losses can be caused by various reasons, among which the post-harvest stage stands out, whose losses can reach values between 20 and 40% of total production in tropical and subtropical regions. This is due to the weather conditions that accelerate the ripening processes, causing the early deterioration of a large number of fruit varieties (Alcívar, 2016).

In this sense, the development of new products based on dehydrated fruit, of high quality, with a reasonable shelf life and attractive to the consumer, would be interesting to expand and diversify its availability in the market. Cuba is also affected by this problem and loses approximately 57% of its fruits every year. Harvest and post-harvest losses are around 30% of total production, and losses in the food distribution phase to domestic markets and cities reach 27% (Rodríguez, 2013).

In order to reduce the aforementioned losses, dehydration has been used as one of the technologies that allows preserving highly perishable foods, especially fruits, including pineapple (Ahmed et al., 2016; Alvis et al., 2016; Estrada et al., 2018).

Pineapple is part of the bromeliad family. The main cultivated types belong to the genus Ananas, which groups several species, including Ananas comosus, which is exploited for commercial purposes.

The first ten exporting countries of fresh pineapple, in tons, are: Costa Rica, the Philippines, Panama, Ecuador, Honduras, Mexico, the Ivory Coast, Ghana, Guatemala and Malaysia (Morales, 2018).

In Cuba, the production of pineapple (Ananas comosus) presents a growth trend, with Ciego de Ávila standing out as the main producer of this fruit (Morales, 2018). Its high demand in the market and its short duration have led to the search for alternatives to solve this problem. The correct conservation of the fruit is presented as a suitable trend for emerging economies and in particular for Cuba where economic development, social growth and environmental protection are some of the fundamental axes to achieve the long-awaited sustainable development.

Despite the studies carried out on this crop by García et al. (2013; 2015; 2018); Ahmed et al. (2016); Alvis et al. (2016); Soares et al. (2016); Estrada et al. (2018), it is required to study osmotic solutions obtained through the combined dehydration process of pineapple for its conservation, and determine which is the Sucrose Syrup solution of osmotic solutions (SO) that best guarantees the organoleptic properties of this fruit.

In this sense, the present work was carried out with the aim of determining the influence of various osmotic solutions obtained through the combined dehydration process of pineapple for its conservation.

METHODS

For the combined dehydration of pineapple, a methodology was developed, which is shown in the heuristic diagram of Figure 1. It begins with the realization of an experimental design where the variables to be controlled are selected in the experiments to be carried out, as well as the selection of the most suitable design that fits the objective of the study. The developed methodology incorporates an analysis by means of expert criteria, which will allow the final decision to be made as to which of the osmotic solutions maintains the best organoleptic properties of the fruit.

FIGURE 1
Heuristic Diagram.
Source: Self-Made

Experiment Design

Due to the characteristics of the data, a single categorical factor design was chosen. It was of the fixed effects model type. This model is the simplest in the design of experiments, in which the response variable may depend on the influence of a single factor, so that the rest of the causes of variation are included in the experimental error. Where:

• Factor: Osmotic solution (SO).

• Factor levels: 9 SO.

Osmotic solutions:

1. MA: Honey Bee

2. Honey A: Honey A from sugar cane

3. Honey A_R: Honey A from lowered sugar cane

4. Honey B: Honey B from sugar cane

5. Honey B_R: Honey B from lowered sugar cane

6. Honey C: Honey C from sugar cane

7. Honey C_R: Honey C from lowered sugar cane

8. JS_ABD: Sucrose Syrup (Direct White Sugar)

9. JS_AC: Sucrose Syrup (Raw Sugar)

• Selection of variables

Response variables

1. P_f: Fruit weight after the process (g)

2. $°B{x}_f:$ Brix of the fruit after the process ($°Bx$)

3. $T_f :$ Fruit temperature after the process ($℃$)

Experimental Work

The experimental work for the combined dehydration process comprises several stages as shown in the following flow diagram (Figure 2). From the reception of the fruit to the solar drying stage as a complement to the process.

FIGURE 2
Flow diagram.
Source: Self-Made

Description of the Experimental Work

• Pineapple reception:

  • The fruit can be acquired through shopping centers that are dedicated to the commercialization of pineapple or any other point of sale. It must be transported in the shortest possible time to the place where the process will take place and kept in a suitable environment.

• Control of quality

  • The fruit must be in perfect condition and at the right ripening point. The fruit cannot have bumps or dark areas as they will be enhanced with the dehydration process, in general the fruit to be used must be ripe, but consistent.

• Prewash and wash:

  • Once the fruit has been selected, it has to be subjected to a thorough washing, which ensures that at the time of peeling, the fruit will be very little contaminated with external pathogens or deterioration agents.

• Cutting, chopping and preparing the fruit:

  • Once the fruit is well washed, the cutting, chopping and preparation process begins to advance with the dehydration process. Here the final destination of the product is taken into account, in order to give it the appropriate shape.

• Measurement of parameters:

  • The following parameters, ^oBrix, temperature and weight, must be controlled for each of the slices.

• Blanching:

  • To carry out the blanching, the fruit should be immersed in an aluminum container with water at a temperature that should range between 60 °C and 80 °C, for a short period of 3 to 4 min.

• Measurement of parameters:

  • Each of the parameters previously controlled is rechecked.

• Immersion in the syrup:

  • Each of the slices must be immersed in the corresponding osmotic solution, taking care that it is completely covered.

• Osmotic dehydration:

  • Dehydration should be carried out in a period of approximately 8 to 10 hours at room temperature, controlling the ^oBrix, the percentage of water and the temperature of the osmotic solution from time to time. The solution should be kept with a slight agitation to ensure that the solution in contact with the fruit has as much sugar as possible since, if not stirred, the process will be slower. Furthermore, the organoleptic properties (odor, flavor, color and texture) are controlled.

• Measurement of parameters:

  • After dehydration is complete, the ^oBrix, weight and temperature of the fruit must be measured again.

• Extraction and draining:

  • The pineapple slices must be extracted with the greatest possible care so as not to damage the product and must be drained to remove any syrup residues that the slices may contain on the surface.

• Solar drying:

  • Osmotically dehydrated fruits still contain humidity levels of 20% to 30%, so complementary drying processes can be applied to extend the shelf life of the product for a longer time.

• Measurement of parameters:

  • After drying is complete, the organoleptic properties (odor, taste, color and texture) are controlled and the ^oBrix, temperature and weight must be measured.

Expert Criteria

The expert criteria was applied in order to evaluate the relevance and feasibility of the organoleptic properties of the osmotically dehydrated pineapple slices in different osmotic solutions after the experimental stage was completed. For this, the experts must be selected to consult and analyze their level of competence.

Obtaining a Mathematical Model from Statistical Data

To obtain the statistical model, the correlation analysis was performed to observe the association between the variables. Pearson's correlation was used for data with normal distribution, while Spearman's correlation was used for the variables that did not follow a normal distribution. Then the multiple regression analysis was performed to obtain the model. In general, the variables that influence the final weight of the fruit, once it was dehydrated, are evaluated.

Dependent variable: Fruit weight

Independent variables:⁰Brix, % of water, temperature.

RESULTS AND DISCUSSION

The behavior of the ⁰Brix for the SO over time can be observed in Figure 3. A stability is observed for all cases after 6 hours of the experiment

FIGURE 3
Variation of oBrix in the SO over time.
Source: Self-Made.

According to the relationship between the dehydration time and the ⁰Brix in the case of solutions, those that showed the best performance were Honey C and Bee Honey. These solutions had a time to stability of 7 hours and 7:40 min, respectively, as well as a variation in the ⁰Brix of 13.64 ⁰Bx and 14 ⁰Bx, respectively. Superior results were achieved by (de Mendonça et al., 2016).

A summary for each SO in the time to stability, as well as in the variation of the ⁰Brix is presented in Table 1.

TABLE 1

Time to stability and ⁰Brix for each of the solutions

The analysis of the relationship between the time of dehydration and the percent of water in the SO, as well as the influence of the temperature can be consulted in Figure 4. There, the behavior of percentages of SO water over time is presented, where a stability for a time similar to that of the ⁰Brix of Figure 3 is observed.

FIGURE 4
Percentage of SO water over time.
Source: self-made.

Figure 5 presents the fruit solids gains after the drying stage for each of the SO. The three SOs that contributed the most in solids were BD Syrup (66%), Honey B (64%) and Lowered Honey B (63%), respectively.

FIGURE 5
Gain of soluble solids from pineapple slices in each SO.
Source: self-made.

On the other hand, the greatest weight losses (Figure 6) were from Honey C reduced (78%), Honey B and Honey A reduced with 76%, respectively.

FIGURE 6
Weight loss of the fruit in each SO.
Source: self-made.

According to the experts’ assessments on the aspects evaluated, 11.1% consider all the organoleptic properties as very adequate, where 88.9% consider these as unsuitable. Only BD Sucrose Syrup of all SO guarantees the best organoleptic properties of the fruit.

There is a trend towards agreement among the experts in reference to the Kendall coefficient. Table 2 presents this coefficient using the contrast statistics.

TABLE 2

Kendall's W Contrast Statistics

The Kendall coefficient resulted in 0.992, where there is a total trend towards agreement among the experts consulted.

Multiple Regression Analysis

The formulation of both dependent and independent variables for the study was as follows:

1. Dependent variable: Weight_ BD Fruit

2. Independent variables:

   • ^oBrix_ BD Sucrose Syrup

   • % Water_ BD Sucrose Syrup

   • Temperature_ BD Sucrose Syrup

An analysis of variance was used to describe the relationship between fruit weight and independent variables. Table 3 summarizes this analysis.

TABLE 3

Analysis of Variance

1. Null hypothesis: There is no relationship between the weight of the fruit and the independent variables.

2. Alternative hypothesis: there is a relationship between the weight of the fruit and in at least one of the independent variables.

3. Significance level: 0.05

4. Decision theory: Reject the null hypothesis (H0) if the smallest P-value of the tests performed is <0.05.

5. Decision: Since the P-value (0.0022) is less than 0.05, there is a statistically significant relationship between the variables with a confidence level of 95.0%.

Therefore, the model equation remains:

where:

The adjusted R-Squared statistic indicates that the model explains 75.65%, so it can be inferred that the model fits correctly for the conditions evaluated in the study.

CONCLUSIONS

• From the drying methods studied, a trend of applying combined dehydration methods was observed, above all due to the energy saving and the simple and easy transference between the osmotic agent and the fruit that they generate.

• A methodology was developed that allows the combined dehydration of pineapple based on the experimental analysis and expert criteria.

• The combined dehydration that had the best organoleptic properties was dehydration with BD Sucrose Syrup.

• It was possible to develop a mathematical model for dehydration combined with BD Sucrose Syrup from statistical data, which was: $\text{Weight}\_FruitBD=-793.779+13.5751\cdot °Brix-11.4982\cdot \text{\% of Water}+10.6665\cdot Temperature$

REFERENCES

AHMED, I.; QAZI, I.M.; JAMAL, S.: “Developments in osmotic dehydration technique for the preservation of fruits and vegetables”, Innovative Food Science & Emerging Technologies, 34: 29-43, 2016, ISSN: 1466-8564.

ALCÍVAR, P.M.R.: Impacto de las exportaciones del sector exportador de piña en las recaudaciones tributarias, periodo 2010-2014, Instituto de altos estudios nacionales universidad de postgrado del estado, Título de Magister en Administración Tributaria, CPA. Guayaquil, Ecuador, 2016.

ALVIS, B.A.; GARCÍA, M.C.; DUSSÁN, S.S.: “Cambios en la textura y color en mango (Tommy Atkins) presecado por deshidratación osmótica y microondas”, Información tecnológica, 27(2): 31-38, 2016, ISSN: 0718-0764, DOI: https://dx.doi.org/10.4067/S0718-07642016000200005.

DE MENDONÇA, S.K.; CORRÊA, G.J.; DE JESUS, J.R.; PEREIRA, M.C.A.; VILELA, M.B.: “Optimization of osmotic dehydration of yacon slices”, Drying Technology, 34(4): 386-394, 2016, ISSN: 0737-3937.

ESTRADA, H.H.; RESTREPO, E.C.; SAUMETT, G.H.; PÉREZ, L.: “Deshidratación Osmótica y Secado por Aire Caliente en Mango, Guayaba y Limón para la Obtención de Ingredientes Funcionales”, Información tecnológica, 29(3): 197-204, 2018, ISSN: 0718-0764, DOI: http://dx.doi.org/10.4067/S0718-07642018000300197.

FRANCO, C.E.: “El desperdicio de alimentos: una perspectiva desde los estudiantes de Administración de Empresas de la UPS Guayaquil”, Revista Retos, 11(1): 51-64, 2016, ISSN: 1390-6291, e-ISSN: 1390-8618, DOI: http://orcid.org/0000-0001-8661-7666.

GARCÍA, H.F.; BEJARANO, L.D.; PAREDES, Q.L.; VEGA, R.R.; ENCINAS, P.J.: “La deshidratación osmótica mejora la calidad de Ananas comosus deshidratada”, Scientia Agropecuaria, 9(3): 349-357, 2018, ISSN: 2077-9917, DOI: http://dx.doi.org/10.17268/sci.agropecu.2018.03.06.

GARCÍA, P.A.; MUÑIZ, B.S.; HERNÁNDEZ, G.A.; GONZÁLEZ, L.M.; FERNÁNDEZ, V.D.: “Análisis comparativo de la cinética de deshidratación Osmótica y por Flujo de Aire Caliente de la Piña (Ananas Comosus, variedad Cayena lisa)”, Revista Ciencias Técnicas Agropecuarias, 22(1): 62-69, 2013, ISSN: 1010-2760, e-ISSN: 2071-0054.

GARCÍA, P.M.; ALVIS, B.A.; GARCÍA, M.C.A.: “Evaluación de los pretratamientos de deshidratación osmótica y microondas en la obtención de hojuelas de mango (Tommy Atkins)”, Journal Información tecnológica, 26(5): 63-70, 2015, ISSN: 0718-0764, DOI: 10.4067/S0718-07642015000500009.

GONZÁLEZ, G.C.G.: “Frutas y verduras perdidas y desperdiciadas, una oportunidad para mejorar el consumo”, Revista chilena de nutrición, 45(3): 198-198, 2018, ISSN: 0717-7518, DOI: http://dx.doi.org/10.4067/s0717-75182018000400198.

GONZÁLEZ, V.L.: “El insostenible desperdicio de alimentos: ¿qué podemos hacer los consumidores?”, Revista CESCO de Derecho de Consumo, 14: 203-216, 2015, ISSN: 2254-2582.

MORALES, A.L.: “Producción y rendimiento del cultivo de la piña (ananas comosus) en Costa Rica, periodo 1984-2014”, Revista e-Agronegocios, 4(2): 1-14, 2018, ISSN: 2215-3462, DOI: https://doi.org/10.18845/rea.v4i2.3681.

RODRÍGUEZ, L.M.; SÁNCHEZ, M.L.: “Consumo de frutas y verduras: Beneficios y retos Consumo de frutas y verduras”, Alimentos Hoy, 25(42): 30-55, 2017, ISSN: 2027-291X.

RODRÍGUEZ, M.M.: Obtención de frutos deshidratados de calidad diferenciada mediante la aplicación de técnicas combinadas, [en línea], Universidad Nacional de La Plata, Tesis en opción al grado científico de Doctor en Ingeniería, Olavarría, Argentina, 2013, Disponible en: https://doi.org/10.35537/10915/29845.

SOARES, K.; GOMES, J.L.; JUNQUEIRA, J.R.; ANGELIS, M.C.; VILELA, M.B.: “Optimization of osmotic dehydration of yacon slices”, Journal Drying Technology, 34(4): 386-394, 2016, ISSN: 1532-2300, e-ISSN: 0737-3937, DOI: https://doi.org/10.1080/07373937.2015.1054511.

Author notes

*Author for correspondence: Damisela Acea del Sol, e-mail: dacea@ucf.edu.cu

Conflict of interest declaration