Prediction of Mathematical Models of the Drying Kinetics and Physicochemical Quality of the Chili Pepper

The present work had as objective to determine the kinetics of drying of the chili pepper, to adjust different mathematical models to the experimental values as a function of the water content and to characterize the same in it’s in natura form and after the drying in the temperatures of 60, 70 and 80 °C. The samples were weighted periodically until reaching the equilibrium. The mathematical models of Wang and Singh, Henderson and Pabis, Newton, Page and Thompson were adjusted to the experimental data. The best adjustment was determined in relation to the highest values of the coefficient of determination (R) and Mean Square Deviation (MSD). The obtained results showed that the drying of the pepper is influenced by the temperature of the drying air. It is concluded that the model of Henderson and Pabis was the one that best fit to the experimental data. The increase of the drying temperature promoted a reduction in the time required for the peppers to reach the moisture of the hygroscopic balance. The parameters of acidity, lipids and proteins remained close at the different drying temperatures used, however higher when compared to the samples in natura. It can be noticed that ashes and vitamin C have suffered considerable decrease as the temperature increased, as a result of the chemical transformations that occurred in the peppers due to heat exposure and loss of moisture.


Introduction
The "aromatic" chili pepper is characterized as a vegetable, belonging to the family Solanaceae and to the genus Capsicum L., and Brazil is known as secondary center of this species, being the Amazon region the one that concentrates greater diversity (Cerqueira, 2012;Araújo et al., 2013).The chili pepper has important characteristics that give quality to food, such as the remarkable aroma, sweet taste, besides possessing medicinal properties as antioxidant and anticancer activity that bring benefits to human health, which can be processed in the form of powder, flakes, pickles, marinades, sauces, canned fruit, jellies, among others (Reis et al., 2011;Santos et al., 2012).
The production of pepper for use as table condiment and industrialized food products has been increasing and is currently a very profitable olive-growing activity, including for small canning industries (Sediyama et al., 2014).The importance of peppers is attributed to their properties improving the taste, aroma and color of food.According to Rêgo et al. (2011) total vitamin C levels vary between pepper species, from 160 to 245 mg/100 g, comparable to guava (200 mg/100 g) and higher than orange (60 mg/100 g).
The market for peppers produced via family farming is also stimulated by the agribusiness producing sauces, whose demand is increasing.In addition to the product marketed in its natural form, there is a range of pepper-based products on the national market or that use it as a component (Oliveira et al., 2014).In Brazil, pepper cultivation is of great importance because of the characteristic of profitability, when the producer adds value to the product, as well as the social importance, because it fits well with the models of family agriculture and small farmer-industry integration (Rufino & Penteado, 2006).
Like other vegetables, the chili pepper is a highly perishable product, because it presents very short post-harvest life, making it necessary to adopt conservation techniques.Therefore, the drying, a method that consists in reducing t responsibl used proce According for the mo mathemati most appr product, su Through th and dryin semi-empi objective t experimen after the dr

Condu
The work University Grande, P green colo

Drying
The drying 60, 70 and approxima

For the dr constant w according
The initial From the d of time

Stati
The results at 5% prob    The results obtained for the physico-chemical evaluations of the in natura pepper were calculated, obtaining the means and the standard deviations (Table 3).The freshly squeezed pepper showed high moisture, which is related to its stability, quality, composition and can affect both its processing as well as its packaging and storage.Lower values of pH (5.48) and acidity (0.035%) were verified by Rebouças et al. (2013) when working with chili pepper in natura.In the in natura pepper, Dambros (2014) obtained values of ashes between 0.87 and 2.32, superior to that verified in this research.

The
Pepper has great nutritional value, attributed to proteins, lipids and vitamins.Dantas et al. (2017) verified a total of 1.9% of proteins in samples of iniquitous black pepper, this was superior to that of this work.Studies performed by Valverde (2011) indicate values of 0.63% for lipids in chilli pepper in natura, a result that is lower than that verified in this research.Castro et al. (2008) verified 107.4 mg of ascorbic acid/100 of sample in chilli pepper, higher than that verified in this work for chilli pepper.
The results of the physicochemical analyzes at temperatures of 60, 70 and 80 ºC are described in Table 4.There was a reduction in the moisture content, pH, total acidity, lipids, ashes, proteins and vitamin C of the peppers submitted to drying.Note.Means followed by the same letter do not differ statistically from each other by the Tukey test at the level of 5% of probability. 1 wet basis; 2 dry base.
During the drying process changes in the quality parameters occurred.The drying with hot air leads to a decrease in nutritional values, besides altering texture, color and causing a slow or incomplete rehydration of the material (Braga, 2007).By evaluating the influence of drying, it was observed that the exposure to heat caused a reduction in the parameters of moisture, pH and vitamin C when compared to the dry and in natura pepper.
Regarding ash and vitamin C values, it can be observed that the gradual increase of the treatment temperature caused significant losses among the dry samples.
The mean value of the pH found in the chili pepper sample was higher than that verified by Braga et al. (2013), in which pH values varying from 5.13 to 5.57 were found in fruits of five progenies of chili pepper.More acidic fruits are naturally more stable to deterioration than foods that have pH close to neutrality.According to Braga et al. (2012) the pH measurement is an important parameter for the determination of a possible and quick deterioration of the product to the presence and growth of microorganisms harmful to health.
It was verified a reduction in the pH of the samples after the drying process.Braga et al. (2013), found values of 5.13 to 5.57 in fruits of five progenies of chilli pepper cultivated in the county of Sobral-CE.Quintero-Ramos et al. (1998), in a study evaluating peppers, observed a decrease in the pH value with the increase of the drying temperature.In this case, the authors attributed this drop to the presence of free carboxylic groups, generated from the demethoxylation of the pectin from the pectin methylesterase action present in the cell wall of the plants.More acidic fruits are, naturally, more stable to deterioration than foods that have pH close to neutrality.
For the acidity value, Borges et al. (2015) verified a value of 0.156% for the Capsicum spp., which is lower than the results verified in this research.According to Reis et al. (2015b), the lower the content of titratable acidity in the fruit, the better is its conservation status, which directly reflects in the quality of a final product for consumption.
Regarding the lipids, Reis et al. (2015b) obtained value (0.20%) for the pepper of the bico variety, which is lower than that verified in this study.As for the ashes result, Farias (2013) that worked with the yield of the peppers of the genus Capsicum obtained 1.09%, being, therefore, lower than that verified in this work for dry pepper.Lower values of proteins were verified by Rinaldi et al. (2008) when studying the varieties of pepper Paloma Hidropônico, Paloma Campo, Impacto Hidropônico and Magali Campo, in which values ranging from 0.09 to 0.12% were found.
Valverde (2011) performed chemical determinations on fresh and processed chilli pepper and observed that there were no differences between protein and lipid contents.There was a reduction in vitamin C content due to exposure to heat, both temperatures presented significant statistical difference.According to Gabas et al. (2003), the loss of ascorbic acid is affected mainly by the application of high temperatures.Valverde (2011) verified for the ascorbic acid content the loss of 88.06% of the pepper in natura compared to the processed one.Passos et al. (2012) also observed reduction of ascorbic acid from 20.46 to 17.30% in the Moringa oleifera leaves during the convective drying process.The vitamins are very sensitive compounds and can be degraded by several factors, such as temperature, oxygen presence, light, moisture, pH, duration of treatment to which the food was subjected, among others (Rebouças et al., 2013).

Conclusions
The model of Henderson and Pabis was the one that best fit to the experimental data.The increase of the drying temperature promoted a reduction in the time required for the peppers to reach the moisture of the hygroscopic balance.The drying constant (k) increased with the raise of temperature, indicating that the drying rate increased with the raise of this variable in the process.The parameters of acidity, lipids and proteins remained close at the different drying temperatures used, however higher when compared to the samples in natura.It can be noticed that ashes and vitamin C have suffered considerable decrease as the temperature increased, as a result of the chemical transformations that occurred in the peppers due to heat exposure and loss of moisture. Figure Figure 3. ).

Table 3 .
Mean and standard deviation of the results obtained for the in natura sample

Table 4 .
Mean values and standard deviation of the physical-chemical analyzes after drying at temperatures of 60, 70 and 80 ° C of the chili pepper samples