Production of spray-dried chickpea instant powders from a proteolytic-amylolytic hydrolysate

Abstract

Current research for alternatives for milk and dairy products, leads the food industry to the application of various processing technologies for raw materials such as legumes with the objective of transforming them into vegetable protein beverages. These products should offer benefits for different types of consumers especially those who adopted nutritional habits such as vegetarianism, veganism or want to avoid allergies. One of the legumes that has been studied for the development of vegetable alternatives to milk is chickpea, which its transformation implies the use of various processing technologies such as thermal and enzyme treatments. From earlier studies it has been found that the combination of thermal extrusion and enzyme hydrolysis of whole chickpea flour with Alcalase and thermoresistant alpha amylase, yield a liquid chickpea hydrolysate rich in protein (20%) and hydrolyzed starch (48%). This liquid chickpea hydrolysate is a promising source for producing an alternative for a novel vegetable milk analog. The withdraw of this alternative is that the beverage requires refrigeration or the employment of aseptic packaging for conserving its properties in order to avoid reduction on its quality and microbial contamination. Drying technologies can overcome this condition by producing powders with a longer shelf life. Therefore, in this research, spray drying technology was used to produce chickpea hydrolysate powders with a prolonged shelf life at room temperature. Since chickpea hydrolysates present 48% of hydrolyzed starch, this may produce operational problems during spray-drying process due to the accumulation of material in the drying chamber. Therefore, inulin and maltodextrin were used as carrier agents with the aim of improving spray-drying processing. These ingredients were evaluated in order to optimize process yield and improved functional properties of chickpea hydrolysate powders for instant beverage preparation. Spray drying conditions were evaluated at 70 and 60°C as outlet temperatures with 180°C inlet air temperature whereas the carrier agents were used in concentrations of 1.5% or 3.0% w/v. Both temperature conditions and type and concentration of carriers were modeled for producing sorption isotherms at 25, 35 and 45°C through Guggenheim-Anderson-de Boer (GAB) and Brunauer-Emmet-Teller (BET). Furthermore, whole, and extruded chickpea flour, freeze-dried and spray-dried hydrolysate powder without carriers were analyzed to evaluate changes in total phenolic contents due to processing. The thermoplastic extrusion of chickpea meal reduced the concentration of phenolic compounds, while hydrolysis increased it. The spray dried products presented statistical differences of total phenolics content in comparison with freeze-dried products due to temperature conditions in spray drying process. Additionally, the assessment of the yield, solubility, and moisture were performed in each powder sample Moisture sorption isotherms analysis revealed that the formulations produced with 1.5% maltodextrin with inlet air temperature of 180°C and outlet air temperature of 70°C, and 3.0% inulin with inlet air temperature of 180°C and outlet air temperature of 60°C yielded the most stable powders in terms of hygroscopicity and certain phase transitions.