Product Quality Characteristics of Solar Dried Chilli Products

Abstract

Chilli is an important commercial crop grown worldwide and used as a condiment, culinary supplement, or vegetable. It's mainly consumed as a dried chilli powder and in other forms such as whole green and red chillies, chilli flakes, sauce, and pickles. Chillies are quite nutritious and are a good source of carbohydrates, proteins, lipids, fibre, mineral salts, and vitamins; however, they are perishable, and a large quantity of them is lost due to inadequate post-harvest handling technologies. Traditionally, chilli has been preserved through direct sun drying, but this method has the disadvantage of contamination by foreign matter and attack by animals and insects. This method also depends on the sunshine hours of a particular area, thus taking a long time. Solar drying is a drying technology that involves the usage of solar drying panels that are economically and environmentally friendly. The moisture content of chillies can be reduced over a shorter period. The products are protected from contamination from foreign matter, insects, and fungal contamination, thus the high-quality dried chilli. The farmer can easily use this method. Moisture sorption isotherm curves showed the inverse relationship decreasing as the temperature increases at constant relative humidity. The analysis was evaluated using the static gravimetric technique with a salt solution to create different relative humidities. The accelerated shelf life method was used where the chillies were stored in the oven at 56 °C. The analysis was done every two days up to the twelfth day, packed into aluminium packages, glass jars, and plastic containers. Fresh chillies were dried to reduce losses associated with quality and microbial loss due to the high moisture content of fresh chilies. Drying was done both for oven and solar drying at 60 °C. Different pre-treatment methods involved blanching with hot water at 85-90 °C and acetic blanching at 90-100°C and soaking in pre-treatment of Na2S2O5 and CaCl2 solution for ten minutes. The physiochemical, nutritional, and microbial characteristics of chillies were then analyzed for oven and solar-dried chilli products. With sensory evaluation, consumer testing xviii affective/ preference test was used with the scores noted over the standard seven-point hedonic scale where seven represented "like very much," and 1 represented "dislike very much ." A panel of 22 participants was used. Parameters to be evaluated were Colour, taste, texture, astringency, bitterness, flavour, and overall acceptability. A meat curry stew was used in tasting the chillies with plain white rice as a carrier. Consumer preference questionnaires were given to the participants to fill in as they conducted the analysis. This study evaluated the quality and safety of solar-dried selected chilli varieties grown in Kenya by solar drying fresh chilli products using solar tunnel driers. Optimizing drying chillies using oven driers, the temperature of 60 °C was found to be the most appropriate as it had minimal effect on the quality characteristics of chillies that included vitamin A, vitamin C, and Colour. The newton model was also used in fitting the drying kinetics data and was found to be a good fit for the data as it had a residual value (Coefficient of determination or R2) close to one of 0.9797 at 60 °C solar drying. The isotherms also exhibited the phenomenon of hysteresis, where the equilibrium moisture content was higher at a particular equilibrium relative humidity for the desorption curve than for adsorption. The G.A.B. (Guggenheim- Anderson-de Boer) model applied in fitting the experimental data at the temperatures of 50 °C, 55 °C, 60 °C, 65 °C and 70 °C which was found to have good prediction accuracy indicated by the high values of R2 (Coefficient of Determination) and the S.E.E. (Standard Error of the Estimation). Of the three packagings used, the aluminium package was found to be the best in terms of nutrients retention [vitamin A of 8.9mg/100g, vitamin C of 13.66g/100g and Colour (Colour was however fairly constant in all the three packages at an average of 1.3 arc tan)] after the end of the shelf life analysis. The microbial analysis was, however, higher in the aluminium package at 2.301 CFU/G for the total viable count and 2.699 CFU/G for yeast and mold. This was attributed to inappropriate pre-processing of the chillies before and during drying that increased the microbial load in the final product after drying. The microbial load for glass and xix plastic packages was 2.699CFU/G and 2.301CFU/G, respectively, for the total viable count with no growth for yeast and mold. There was a significant difference in all the parameters analyzed, with more beta carotene retention for oven-dried chillies, with the range being 28.4 to 23.2mg/100 g. This was in agreement with reports done by (Kamal et al., 2019). The ascorbic acid quantity was also significantly different, with ranges from 52.44 to 24.32g/100g. The effect of the pre-treatment on Colour was also significant. The microbial analysis showed variations in the microbial also that were attributed to the areas of collection of the chillies or the type of treatment done to the chillies. There was no significant difference between oven-dried chillies and solar-dried chillies on the parameters of Colour, taste, astringency, bitterness, texture, and overall acceptability. The flavour, however, had some significant differences between solar and oven-dried chillies. The findings will inform on the commercial viability of dried chilli products concerning meeting food safety standards in Kenya to promote the industry's commercialization and value addition of chilli adoption. This can be done by solar drying fresh chillies and effectively storing the finally dried chillie products under aluminium packaging, showing the best nutritional composition preservation. Care should also be taken when handling both before and after drying to prevent recontamination of the final dry product. This study, therefore, will guide the solar drying technique of fresh chillies from the study of the quality characteristics and storage of the finally dried chillies from the moisture sorption isotherm and the storability study. The sensory analysis guided the consumer's acceptability of the finally dried chillies.