João Luiz Andreotti Dagostin

Modelling studies by adsorption for the removal of sunset yellow azo dye present in effluent from a soft drink plant

This paper reports a study on the adsorption of the dye sunset yellow, present in an aqueous synthetic solution and a real effluent from a soft drink plant, onto granular-activated carbon derived from coconut husks, using a batch system. The kinetic equilibrium was investigated using two different dye concentrations (102 and 103 mg L−1) at 25°C and 150 rpm. The adsorption isotherms and thermodynamics parameters were evaluated at 25°C, 35°C, 45°C and 55°C, using the synthetic and real effluents (5–103 mg L−1). Experimental data showed that the adsorbent was effective in the removal of sunset yellow dye and the contact time required to attain the adsorption equilibrium did not exceed 10 h. The adsorption capacity was not influenced within a wide range of pH values (1–12), although at high dye concentrations it increased with increasing temperature for both the synthetic and real effluents. The Redlich–Peterson isotherm best represented the equilibrium data of the system. The negative values obtained for Δ G0 and Δ H0 suggest that this adsorption process is spontaneous, favourable, and exothermic. The positive values for Δ S0 indicate an increase in the entropy at the solid/liquid interface. Based on the results of this study, adsorption appears to be a promising method for the removal of sunset yellow azo dye from effluent generated at soft drink plants.

Use of Blanching to Reduce Antinutrients, Pesticides, and Microorganisms

Undesirable substances may occur in vegetable species as endogenous substances called antinutrients. Other undesirable compounds may exist in foods through external sources, due to the contamination by pesticides and microorganisms for example. Some of the positive side effects incurring in blanched foods comprise the removal of these substances and microorganisms, which may imply quality loss, toxicological problems, and infectious diseases. The removal rate of each substance is dependent on parameters related to the process, food characteristics, and substance type. In most processing lines, a few methods are auto sufficient in removing undesirable substances and chemicals from foods, and most of these methods are too aggressive. For microorganisms, sterilization processes can completely remove microbial contamination, but only a fraction of foods can be processed by such a rigorous operation. Blanching is an adequate method that can be used to remove part of the undesirable substances and lower microbial content of raw materials with less changes in their original characteristics. In this chapter, it will be shown and discussed how blanching affects some antinutrients, pesticides, and microorganisms on foods, with a brief presentation of each substance to better understand their role on the physiological disorders caused in humans.

Blanching as an Acrylamide Mitigation Technique

Food processing is a fundamental activity applied to extend the shelf-life, to improve stabilization, increase the nutritional value, provide convenience and give special characteristics to foods and foodstuffs. Within the set of thermal technologies applied in food processing, cooking is a step intended to give unique sensory properties, as texture, flavor, color, and taste. During the processes of frying, baking, or roasting for some types of foods—especially carbohydrate-rich foods—Maillard reactions may take place, yielding a pleasant flavor and color compounds. Some pathways of the Maillard reaction chain, however, may produce undesirable substances like acrylamide, furans, and furfurals. Acrylamide in particular concerns researchers and consumers since it is classified as a probable human carcinogen. In this chapter, blanching will be presented as an acrylamide mitigation technology, highlighting some of the most relevant studies involving the method, the effect of time and temperature, and the combination of different technologies to blanching.

Microwave drying and NIR spectroscopy for rapid moisture measurement of yerba mate (Ilex paraguariensis) leaves during storage

ABSTRACT Microwave technology was assessed and compared with traditional kiln drying to analyze the moisture content of yerba mate leaves/sticks. The moisture content was also measured by near-infrared spectroscopy (NIR). The samples were stored under different conditions of temperature, relative humidity (RH), and time, until 180 days. The microwave method was similar to the official kiln drying method when 900 W/4.3 min was applied. The use of microwave drying showed similar results to the kiln method in the moisture range of 0–10 g/100 g raw material. The partial least square (PLS) models obtained from NIR spectroscopy showed low predictive power, due to the natural heterogeneity of the samples.