The aim of this research was to knowing if it would improve the shelf life of the lemons that were stored in hermetically polystyrene containers closed, as same that were placed in a refrigerated chamber with temperature of 10 °C inside, high relative humidity (85%) and renovation of the air by action of the compressor of the chamber. Lemons cv “Lisboa” were cut directly from the orchard and washed with chlorinated water at 150 mg⋅L−1 sodium hypochlorite. The study variables were the color of the epicarp (shell) and the endocarp (pulp), polar and equatorial diameter, firmness of the pulp and total soluble solids concentration ( °Brix) in the endocarp. The tone and purity of the yellow color of the shell (epicarp) and pulp or endocarp of the oranges increased significantly within polystyrene containers and, consequently, its quality was preserved and its shelf life was extended to more than 100 days without that they have symptoms of deterioration, by losses polar and equatorial diameter or decrease in total soluble solids. Inside closed containers polystyrene the temperature decreased to 2.0 °C in the refrigerated chamber, so that the principle of thermal insulation polystyrene reaffirmed, and its functionality for packaging products, such as fruits, resolve some of their physiological problems themselves, to prolong its shelf life and improve its presentation.
Lemon Lisboa or Lisbon is one of these fruits that is grown in the Valley of Mexicali, Baja California, Mexico, where it occupies the second place in cultivated surface, since the first place corresponds to the lemon Eureka (Italian); while the third and fourth place is represented by lemon Colima and Persa, respectively [
Fruits and vegetables are important in human nutrition and are good sources of energy, fat, carbohydrates, calcium, phosphorus, iron, magnesium and vitamins such as A, B6, B12, C, thiamin, riboflavin and niacin. They provide more than 90% of vitamin C in human nutrition and are also excellent sources of fiber, a component of great importance in the diet [
The demand for minimally processed and refrigerated fruits and vegetables is continuous, which must be fresh, convenient, of high quality and safe for the health of the consumer [
The storage techniques used after the harvest, once the fruits have been packaged for fresh commercialization, have the purpose of preserving the quality of the same, taking into account the adequate environmental conditions that allow to reducing the speed of the vital processes of these products, and dispose of them for longer periods than the normal ones, in addition to offering fresh products to distant markets and decreasing losses during their commercialization. Among the most widely used techniques for the conservation of fruits and vegetables are refrigeration, the use of controlled atmospheres, the use of ethylene absorbents, the application of covering films and the exogenous application of phytoregulators [
The technique of conservation in modified atmosphere (AM) consists of packing food products in materials with diffusion barrier gases, in which the gaseous environment has been modified to reduce the degree of respiration, reduce microbial growth and delay the enzymatic deterioration with the purpose of extending the useful life of the product. Inside a closed container, the gaseous atmosphere changes continuously throughout the storage period due to the influence of different factors such as the respiration of the packaged product and the biochemical changes [
After being harvested, fresh fruits and vegetables continue their metabolic processes, consume O2, and produce CO2 and water vapor. The modification of the atmosphere around the product is carried passively by the effect of breathing [
Depending on the requirements of the food to be packaged, an atmosphere with environments rich in CO2 and poor in O2 will be required, which reduces the respiration process in the products, conserving their physicochemical, organoleptic and microbiological characteristics for a longer time [
Expanded polystyrene is used to package and pack food [
It has been shown that giant-bananas (AAA) Cavendish postharvest increase shelf life when stored in closed polystyrene containers inside a refrigerated chamber at temperatures of 10˚C - 12˚C [
The tone and purity of the yellow color of the epidermis and the pulp of the oranges increased significantly within the polystyrene containers and, consequently, their useful life lasted for more than 100 days, without any symptoms of deterioration losses of polar and equatorial diameter or by reduction of total soluble solids, compared with said characteristics of the oranges in the lower tray of a refrigerated chamber [
The objective of this investigation was to determine if the shelf life of lemons cv “Lisboa” is increased, when these are stored inside hermetically sealed polystyrene containers, placed in closed environments with a temperature of 10˚C, high relative humidity (85%) and frequent renewal of air in the storage space.
The experiment was carried out in the agricultural center of the University of Arizona in Yuma, AZ, USA, with coordinates 32˚42'45''N and 114˚42'18''W, in a laboratory equipped for storage of climacteric fruits. The orchard of lemons of the variety “Lisbon” is in the Mesa Station of the same university, located in Somerton, AZ, EU at 33˚24'54''N and 111˚49'53''W, from where the lemons were harvested with the necessary care (
The statistical analysis was made on the basis of experimental design of randomized complete blocks with four replications and five treatments: lemons freshly harvested and evaluated (week 0) before others were packed in containers, lemons confined in a closed polystyrene container which was opened at 8 weeks, another that opened at 12 and one more that was opened at 16 weeks, plus the witness that consisted of the lemons packed in the open container.
The study variables were fruit weight, equatorial diameter, shape, shell color (epicarp), firmness and Brix degrees (total soluble solids). The weight, shape and color of the shell were examined with the Autoline Fruit Sorting System. The equatorial diameter was measured with a vernier and firmness with a penetrometer fruit pressure tester mod. Ft. 011 on the surface of the lemons to obtain the values in pounds; while the total soluble solids were analyzed with a digital refractometer (PR 32, ATAGO, EU), by placing juice drops of the lemons in the refractometer receiver. The measurements were carried out from the day of packaging (week 0); likewise, at 8, 12 and 16 weeks.
The analysis of variance was made with the statistical program SAS version 5 [
The analysis of variance of the weight of the lemons indicated highly significant differences (P ≤ 0.001) with standard deviation of 9.22 g and a CV = 8.98%, in such a way that the multiple comparison of means shown in
Significant differences were found with the analysis of variance of the equatorial diameter of the lemons (P ≤ 0.052), standard deviation of 0.13 in, and a CV = 5.75%. The multiple comparison of means indicated in
Treatments | Weight (g) | Equatorial diameter (in) | Shape (sh) |
---|---|---|---|
Week 0 | 103.91 a | 2.27 ab | 0.72 ab |
Week 8 | 105.99 a | 2.33 a | 0.71 b |
Week 12 | 105.39 a | 2.27 ab | 0.80 a |
Week 16 | 101.91 ab | 2.24 ab | 0.74 b |
Control | 94.88 b | 2.21 b | 0.70 b |
Means with the same letter in each column are statistically equal (Tukey, α ≤ 0.05).
possible to note that, after eight weeks of being packed, the lemons had 5.4% (0.12 in) More of equatorial diameter than the controls, at 12 weeks the increase it was 2.7% (0.06 in), and at 16 weeks the increase was 1.34% (0.03 in), although without statistical difference with the control; however, at 16 weeks the diameter of the lemons decreased 1.3% (0.03 in) compared to the one they had when packaged, the appearance of the lemons can be seen in
The analysis of variance of the shape (sh) of the lemons indicated highly significant differences (P ≤ 0.010), with standard deviation of 0.093 (sh) and CV = 12.6%, in such a way that the multiple comparison of means shown in the
The analysis of variance for the green-yellow (g/y) color of the epicarp indicated highly significant differences (P ≤ 0.000), standard deviation of 3.3 g/y and CV = 3.4%. The multiple comparison of means (
The firmness of the lemons occurred with highly significant differences (P ≤ 0.000), standard deviation 0.65 lb and a CV = 18%; the multiple comparison of means (
Treatments | Color (green-yellow g/y) | Firmness (lb) | ˚Brix |
---|---|---|---|
Week 0 | 93.9 b | 3.3 b | 7.2 c |
Week 8 | 98.1 a | 4.4 a | 7.7 b |
Week 12 | 97.8 a | 3.3 b | 7.5 bc |
Week 16 | 92.1 b | 3.4 b | 7.2 c |
Control | 98.0 a | 2.2 b | 8.7 a |
Means with the same letter in each column are statistically equal (Tukey, α ≤ 0.05).
The Brix degrees also occurred with highly significant differences (P ≤ 0.000), standard deviation of 0.45 ˚Brix and CV = 5.85%; the multiple comparison of means (
These results coincide with those of Reyes et al. [
From these results, it can also be deduced that the use of polystyrene containers fulfilled the fact referred by Yildiz [
Likewise, these results will also complement the knowledge of the technicians and producers so that, once the lemons have been packaged for fresh commercialization, they have the quality that the consumer demands, in the environmental conditions that the closed polystyrene containers give, with the which the speed of the vital processes of lemons can be reduced, and also have longer periods than normal, in addition to offering them fresh to distant markets and reducing losses during their commercialization, as they suggest Parikh et al. [
In addition, these results are related to what was reported by González [
With the closed polystyrene containers, the conditions suitable for the requirements of lemons are also provided, such as food to be packaged, since as Parry [
Therefore, the use of hermetically sealed polystyrene containers to package lemons cv “Lisboa”, confirmed what was reported by Perdomo [
Among the evaluated variables that affect the quality of the lemons, 66.7% of them (weight, equatorial diameter, shape and firmness) of the lemons stored in the closed polystyrene containers, remained above those of the lemons confined in the open container inside the refrigerated chamber (control) until 16 weeks (120 days), while 33.3% of them (green-yellow color of the epicarp or shell and total soluble solids or ˚Brix) remained below those of the control, without the green-yellow being <90 or the ˚Brix ≥ 8.7 that indicate a decrease in acidity, so that both levels of the characteristics lead to the deterioration of the lemons. Since the shelf life of the lemons was prolonged, then the polystyrene containers can be another technology to conserve lemons for longer than usually considered (12 weeks) in the refrigerated chambers currently used by the producer.
The authors declare no conflicts of interest regarding the publication of this paper.
Obregón-Burgueño, Y.B., Velázquez-Alcaraz, T. de J., Partida-Ruvalcaba, L., Garcia-Lopez, A.M., Ayala-Tafoya, F., Díaz-Valdés, T. and Wright, G.C. (2018) Quality and Shelf Life of Lisboa Lemon within Polystyrene Containers in Refrigerated Chamber. Agricultural Sciences, 9, 1107-1114. https://doi.org/10.4236/as.2018.99077