Effect of Blanching in Water and Sugar Solutions on Texture and Microstructure of Sliced Carrots

Abstract

Thermal processing of vegetables has pronounced effects on the cell structure, often negatively affecting the final textural properties of the product. In order to study the effect of thermal processing and the protective effect of sugars on the tissue, sliced carrots were subjected to blanching treatments under different time and temperature combinations both in water and in 4% sugar solutions made of trehalose or maltose. The influence of these process conditions on mass transfer, texture, and microstructure (Cryo-scanning electron microscopy) was thus investigated. The total mass loss of all the samples blanched in water was associated to their cook value (C(100)(18)) except for the overprocessed one (90 °C, 10 min) that showed a total mass change significantly lower due to water uptake. The use of trehalose and maltose in the blanching solution reduced the solute loss while increasing the water loss. Microstructural analysis of the differently blanched carrots showed detachments between adjacent cell walls as well as plasmolysis phenomena as the time and temperature of the thermal treatment were increased. A protective effect of both sugars on cell structures was observed mostly in the sample treated at 90 °C. At macroscopic level, textural changes upon blanching were observed by a penetration test. As blanching time was increased, samples processed at 75 °C showed a hardness increase, while those processed at 90 °C showed a hardness decrease. However, both trehalose and maltose did not exert significant effects on the textural properties of blanched carrots when compared with those blanched in water. Practical Application: The results of this study could offer interesting perspectives in the optimization of the heat treatments in order to preserve the quality of semi-finished processed vegetables. Furthermore, the microstructural analysis is nowadays an important investigation tool that could contribute to a deeper understanding of both the effects of processing and ingredients on the vegetable microstructure and its relationship with the changes occurring on the quality properties at macroscopic level.

Silver nanoparticles-based plasmonic assay for the determination of sugar content in food matrices

“…Chromatographic analyses were conducted using a carbohydrates separation column (CarboPac PA20, 3 mm × 150 mm, Dionex) with a preguard column (CarboPac PA20, 3 mm × 30 mm, Dionex) according to Neri et al [38] with some modifications. 5.0 × 10 -2 mol L -1 NaOH was used as mobile phase.…”

Effect of Dipping and Vacuum Impregnation Pretreatments on the Quality of Frozen Apples: A Comparative Study on Organic and Conventional Fruits

“…Sugar extraction was carried out according to Neri et al. (). The chromatographic analysis was performed by using a carbohydrates separation column (CarboPac PA20, 3 mm × 150 mm, Dionex) with a preguard column (CarboPac PA20, 3 mm × 30 mm, Dionex).…”

“…In order to improve frozen products' quality, freezing pretreatments are also conventionally applied (Bunger et al, 2004). Processing aimed to enrich plants tissues of acidulants, thermo-and cryoprotectants, and antioxidants prior to freezing is recognized, in fact, to positively affect the physical and functional properties of the processed products (Mastrocola, Pittia, & Lerici, 1996;Neri, Hernando, Pérez-Munuera, Sacchetti, & Pittia, 2011;Oms-Oliu et al, 2010) and to limit browning phenomena (De Ancos, Sanchez-Moreno, De Pascual-Teresa, & Cano, 2012). Among these, VI has been recognized as a useful technology to enrich plant tissues with desirable solutes (for example, flavors, cryoprotectans, firming agents, antioxidants, probiotics, vitamins, and minerals) capable of stabilizing and/or improving the quality properties of food products (Neri et al, 2016).…”

“…Sugars were determined by high-performance liquid chromatography (HPLC) analysis by using an ICS 3000 Ionic Chromatograph (Dionex, San Donato Milanese, Italy) equipped with an ICS 3000 SP pump and ICS 3000 ED detector. Sugar extraction was carried out according to Neri et al (2011). The chromatographic analysis was performed by using a carbohydrates separation column (CarboPac PA20, 3 mm × 150 mm, Dionex) with a preguard column (CarboPac PA20, 3 mm × 30 mm, Dionex).…”

Yacon Inulin Leaching During Hot Water Blanching

“…Thermal processing of vegetables has pronounced effects on the cell structure, often negatively affecting the final textural properties of the product, and texture changes upon blanching and cooking are mainly related to the gelification of pectins located in the cell walls as well as their solubilization and degradation (Neri et al, 2011). In agreement with Paredes et al (2007), the cell damages determined by the blanching treatment cause a decrease of the resistance to mass transfers and, thus, favor the loss of water and/or solutes from the vegetable matrix.…”