Evaluation of carotenoids and furosine content in air dried carrots and parsnips pre-treated with pulsed electric field (PEF)

Application of novel pretreatment technologies for intensification of drying performance and quality attributes of food commodities: a review

Drying is an energy-intensive process that can be reduced by the application of pretreatment prior to drying to enhance mass transfer and minimize energy consumption. This review summarizes the mechanistic aspects and applications of emerging pretreatment approaches, namely ohmic heating (OH), ultrasound (US), high pressure processing (HPP), and pulsed electric field (PEF), with emphasis on the enhancement of mass transfer and quality attributes of foods. Novel pretreatments significantly improved the drying efficiency by increasing mass transfer, cavitation, and microchannel formation within the cell structure. Various processing parameters have great influence on the drying performance and quality attributes of foods. Several studies have shown that novel pretreatments (individual and combined) can significantly save energy while improving the overall drying performance and retaining the quality attributes. This work would be useful for understanding the mechanisms of novel pretreatment technologies and their applications for future commercial research and development activities.

A Pulsed Electric Field Accelerates the Mass Transfer during the Convective Drying of Carrots: Drying and Rehydration Kinetics, Texture, and Carotenoid Content

The pulsed electric field (PEF) is a non-thermal food processing technology that induces electroporation of the cell membrane thus improving mass transfer through the cell membrane. In this study, the drying and rehydration kinetics, microstructure, and carotenoid content of carrot (Daucus carota) pretreated by PEF during convective drying at 50 °C were investigated. The PEF treatment was conducted with different field strengths (1.0-2.5 kV/cm) using a fixed pulse width of 20 µs and at a pulse frequency of 50 Hz. The PEF 2.5 kV/cm showed the shortest drying time, taking 180 min, whereas the control required 330 min for the same moisture ratio, indicating a 45% reduction in drying time. The rehydration ability also increased as the strengths of PEF increased. PEF 2.5 kV/cm resulted in 27.58% increase in moisture content compared to the control after rehydration (1 h). Three mathematical models were applied to the drying and rehydration data; the Page and Peleg models were selected as the most appropriate models to describe the drying and rehydration kinetics, respectively. The cutting force of the sample was decreased as the strength of PEF increased, and a more homogeneous cellular structure was observed in the PEF pretreatment group. The reduction in drying time by PEF was beneficial to the carotenoid content, and PEF 2.5 kV/cm showed the highest preservation content of carotenoid. Overall, these results suggested that the pretreatment of PEF and the drying and rehydration rate influence the quality of products, functional components, and cellular structure.

Kinetics of Carotenoids Degradation during the Storage of Encapsulated Carrot Waste Extracts

The encapsulates of carrot waste oil extract improved the antioxidant properties of durum wheat pasta. The aim of this research was to study the kinetics of carotenoids degradation in the freeze-dried (FDE) and spray-dried (SDE) encapsulates of carrot waste extract during storage at four different temperatures (+4, +21.3, +30, +37 °C) up to 413 days by HPLC. Carotenoids levels decreased as a function of time and temperature, following zero-order kinetics. At 4 °C carotenes were stable for at least 413 days, but their half-lives decreased with increasing temperatures: 8-12 months at 21 °C; 3-4 months at 30 °C; and 1.5-2 months at 37 °C. The freeze-drying technique was more effective against carotenes degradation. An initial lag-time with no or very limited carotenes degradation was observed: from one week at 37 °C up to 3 months (SDE) or more (FDE) at 21 °C. The activation energies (Ea) varied between 66.6 and 79.5 kJ/mol, and Ea values tended to be higher in FDE than in SDE.

Phenolic Compounds Recovery from Blood Orange Peels Using a Novel Green Infrared Technology Ired-Irrad®, and Their Effect on the Inhibition of Aspergillus flavus Proliferation and Aflatoxin B1 Production

The intensification of total phenolic compound (TPC) extraction from blood orange peels was optimized using a novel green infrared-assisted extraction technique (IRAE, Ired-Irrad^®) and compared to the conventional extraction using a water bath (WB). Response surface methodology (RSM) allowed for the optimization of ethanol concentration (E), time (t), and temperature (T) in terms of extracted TPC and their antiradical activity, for both WB extraction and IRAE. Using WB extraction, the multiple response optimums as obtained after 4 h at 73 °C and using 79% ethanol/water were 1.67 g GAE/100 g for TPC and 59% as DPPH inhibition percentage. IRAE increased the extraction of TPC by 18% using 52% ethanol/water after less than 1 h at 79 °C. This novel technology has the advantage of being easily scalable for industrial usage. HPLC analysis showed that IRAE enhanced the recovery of gallic acid, resveratrol, quercetin, caffeic acid, and hesperidin. IR extracts exhibited high bioactivity by inhibiting the production of Aflatoxin B1 by 98.9%.

Recent processing of fruits and vegetables using emerging thermal and non-thermal technologies. A critical review of their potentialities and limitations on bioactives, structure, and drying performance

Fruits and vegetables have rich bioactive compounds and antioxidants that are vital for the human body and prevent the cell from disease-causing free radicals. Therefore, there is a growing demand for high-quality fruits and vegetables. Nevertheless, fruits and vegetables deteriorate due to their high moisture content, resulting in a 40-50% loss. Drying is a common food preservation technique in the food industry to increase fruits and vegetables' shelf-life. However, drying causes chemical modifications, changes in microstructure, and bioactives, thus, lowering the final product's quality as a considerable amount of bioactives compounds and antioxidants are lost. Conventional pretreatments such as hot water blanching, and osmotic pretreatment have improved fruit and vegetable drying performance. However, these conventional pretreatments affect fruits' bioactive compounds retention and microstructure. Hence, emerging thermal (infrared blanching, microwave blanching, and high-humidity hot-air impingement blanching) and non-thermal pretreatments (cold plasma, ultrasound, pulsed electric field, and edible films and coatings) have been researched. So the question is; (1) what are the mechanisms behind emerging non-thermal and thermal technologies' ability to improve fruits and vegetables' microstructure, texture, and drying performance? (2) how do emerging thermal and non-thermal technologies affect fruits and vegetables' bioactive compounds and antioxidant activity? and (3) what are preventing the large-scale commercialization of these emerging thermal and non-thermal technologies' for fruits and vegetables, and what are the future recommendations? Hence, this article reviewed emerging thermal blanching and non-thermal pretreatment technologies, emphasizing their efficacy in improving dried fruits and vegetables' bioactive compounds, structural properties, and drying performance. The fundamental mechanisms in emerging thermal and non-thermal blanching pretreatment methods on the fruits and vegetables' microstructure and drying performance were delved in, as well as what are preventing the large-scale commercialization of these emerging thermal and non-thermal blanching for fruits and vegetables, and the future recommendations. Emerging pretreatment approaches not only improve the drying performance but further significantly improve the retention of bioactive compounds and antioxidants and enhance the microstructure of the dried fruits and vegetables.

Advanced osmotic dehydration techniques combined with emerging drying methods for sustainable food production: Impact on bioactive components, texture, color, and sensory properties of food

The food industries are looking for potential preservation methods for fruits and vegetables. The combination of osmosis and drying has proved the efficient method to improve the food quality. Osmotic dehydration is a mass transfer process in which water molecules from the food move to an osmo-active solution and the solutes from the solution migrate into the food. Advanced osmotic dehydration techniques such as electric field pulse treatment, ultrasonic and microwave-assisted dehydration, pulsed vacuum, and osmodehydrofreezing can improve the nutritional quality (bioactive) and sensory properties (color, texture, aroma, flavor) of fresh and cut-fruits without changing their reliability. Emerging osmotic dehydration technologies can preserve the structure of fruit tissue by forming microscopic channels and increasing effective water diffusivity. However, it is important to analyze the effect of advanced osmotic dehydration techniques on the quality of food products to understand the industrial scalability of these techniques. The present paper discusses the impact of recent osmotic dehydration techniques on bioactive, antioxidant capacity, color, and sensory profile of food.

Loss or Gain of Lipophilic Bioactive Compounds in Vegetables after Domestic Cooking? Effect of Steaming and Boiling

Lipophilic antioxidants are essential components, which have been pointed as bioactive beneficial for human health. This study aimed at evaluating the effect of domestic cooking (boiling, steaming) on the main carotenoids (lutein and β-carotene) and tocols in four different green leafy vegetables: Sonchus asper L. Hill, Sonchus oleraceus L., Spinacia oleracea L. and Cichorium intybus L. The total content of the analyzed compounds was determined following the method of alkaline hydrolysis of the matrix and solvent extraction. The leaching of soluble solids after domestic cooking was found to determine a gain in the investigated bioactive compounds in the cooked vegetables, so to cause an apparent content increase in all leafy vegetables, when expressed as mg/100 g dry matter. Considering solid losses, all lipophilic compounds were not affected by boiling; on the contrary, steaming slightly significantly decreased the contents of lutein and β-carotene (on average 20 and 15%, respectively).

Evolution of Carotenoid Content, Antioxidant Activity and Volatiles Compounds in Dried Mango Fruits (Mangifera Indica L.)

The aim of this research was to study the evolution of carotenoid compounds, antioxidant β-ctivity, volatiles and sensory quality in two mango cultivars dried at 50, 60 and 70 °C. Total carotenoids in fresh samples were about 12 and 6 mg/100 g (dry basis) in Keitt and Osteen samples, respectively. β-carotene was the main carotenoid, representing about 50% of total carotenoids. In both cultivars, carotenoids were more susceptible to drying at 60 °C. Total phenols and metal reduction activity were higher in Osteen than in Keitt, which had higher values in radical scavenging capacity. The antioxidant activities were best preserved with drying temperatures at 50 °C in Keitt and 60 °C in Osteen fruits. Fresh Osteen mango fruits had a volatile compound content of about 37.1, while Keitt of about 5.2 mg/kg (dry basis). All the compounds with odorous impact were significantly reduced after drying. As regards organoleptic characteristics through sensory analysis, Keitt dried mangoes were quite similar to the fresh product, compared to Osteen.