Effect of microwave blanching and brine solution pretreatment on the quality of carrots dried in solar‐biomass hybrid dryer

Abstract

The effect of microwave blanching time (0–3 min), followed by dipping in brine solution (sample to solution ratio 0–4) prior to drying of carrot slices and shreds in solar‐biomass hybrid dryer on the final moisture content of the samples, drying rate, rehydration ratio, color change, textural firmness change, and beta carotene content was studied using two‐factor 3 level factorial design. Pretreatment parameters were optimized using response surface methodology. As the microwave blanching time increased, there was an increase in the drying rate, rehydration ratio, and beta carotene content, with minimum changes in textural firmness, color, and final moisture content. Increase in brine solution to sample ratio impacted the drying rate and beta‐carotene content in the samples, positively. Microwave blanching time of 3 min and brine solution to sample ratio of 2 were found to be the optimum pretreatment parameters for drying of carrot slices and shreds. Practical applications Solar energy is abundantly available in tropical countries like India and this renewable energy can be utilized to preserve food materials, economically. Carrots being seasonal in nature require be drying and preserving for further use during off seasons, and potential of a solar‐biomass hybrid dryer can be tapped to reduce the energy requirement for a high energy requiring processing operation like drying. The study recommends pretreatments to carrot slices and shreds like dry microwave blanching, followed by brine solution dipping of carrot slices and shreds for better quality in terms of faster moisture removal leading to lower drying period, beta‐carotene retention, better rehydration characteristics as compared to control samples, where no such pretreatments were given. This recommendation can be very well be utilized to reduce the energy demand in food processing industry.

Assessment of pretreatments on drying kinetics and quality characteristics of thin-layer dried red pepper

“…The rehydration test was performed according to the methods of Vega-Gálvezet al ( 2009) and Delfiya et al (2017). To determine the rehydration capacity (RC) of the dried peppers, the sample was placed in a beaker containing distilled water at a ratio of 1:50 (w/w) at 25 °C, mixed thoroughly, and allowed to rehydrate for 6h.…”

“…Pretreatments play an important role in the acceleration of the drying rate in many fruits and vegetables (Srimagal et al, 2017). Some common treatments used prior to drying include hot water blanching (HWB) (Sharma et al, 2015), chemical dipping (Delfiya et al, 2017), microwave blanching (MWB) (Sabry et al, 2016;Srimagal et al, 2017) ohmic heating (OH) (Salengke and Sastry, 2005), ultrasound (US) (Mothibe et al, 2011), and pulsed electric field (PEF) (Won et al, 2015).…”

“…MWpretreated vegetables were found to have better nutritional quality in comparison with HWB-treated vegetables because of advantages such as shorter processing periods and improved heating efficiency (Nayak et al, 2018). Previous studies have shown that MWB increased the drying rate of carrot during the drying period and thus, reduced the drying time (Sabry et al, 2016;Delfiya et al, 2017). OH as an alternative processing method also has several advantages when compared to a conventional hot water process, including fast and uniform heating, less energy consumption, better product quality, less soluble nutrient loss, and less water usage (0.5 kg of water per kg of food product) (Bhat et al, 2017).…”

The optimization of the drying process and vitamin C retention of carambola: An impact of storage and temperature

“…Conventional or convective drying needs more time and heat though this is cost‐effective and extensively accepted practice in the food manufacturing processes (Kipcak et al., 2019). Pretreatment is a vital stage prior to the process of food materials which affects the drying time, dried foods quality, lessens sluggish changes arise throughout dehydration and storage ( Delfiya et al., 2018; Khan et al., 2019).…”

Environmental Assessment of a Hybrid Solar-Biomass Energy Supplying System: A Case Study

“…Generally, the solar-biomass systems can make full use of local biomass resources and solar radiation resources, local energy structure can be improved by using such renewable energy systems and some of the environmental problems like frequent haze may be solved effectively. It should be noted that most of the hybrid solar-biomass systems are focusing on drying [10], power generation [11,12], biomass gasification [13] or multi-generation [9,14,15], only a few systems are focusing on house energy supplying [16,17]. Even among hybrid solar-biomass energy systems, most biomass subsystems directly burn agricultural residues or forestry biomass.…”