Ultra-sonicated vacuum drying's effect on antioxidant activity, TPC, TFC and color of elephant apple slices

Experimental investigation of modified indirect solar dryer with integrated thermal storage material for drying of dhekia (Diplazium esculentum) fern

Food product drying is a crucial stage in the preservation of crops and agricultural by-products that are used as raw materials for numerous end applications. The novelty of the study is the application of a phase change material in a solar dryer to improve the effectiveness of drying and reducing the overall drying period for drying while retaining/improving the quality parameters of the dried dhekia (Diplazium esculentum). The modified indirect thermal storage integrated solar dryer made up of a single-pass solar collector is attached with the drying chamber of 16.5 kg capacity. A thermal energy storage system prepared with paraffin wax embedded inside the drying cabinet was used. The proposed solar dryer has a thermal efficiency that is 11 ± 0.2% greater than the conventionally constructed solar dryer and reduces drying time by 40 ± 2.1%. Drying kinetic analysis of dhekia was performed, and two new drying kinetic models were proposed to predict moisture ratio. From statistical analysis, it was found that the chi square value and root mean square error value fits well for the proposed models. The anti-oxidant, total phenolic content, and total flavonoid content values of samples dried in solar dryer exhibit better results compared to fresh, tray dried, and open sun-dried samples. The developed dryer shows better results in saving drying time and quality of the product. Due to its affordability and long-term solution for drying fresh farm goods, this dryer can be very helpful to small-scale farmers.

Colour, nutritional composition and antioxidant properties of dehydrated carrot (Daucus carota var. sativus) using solar drying techniques and pretreatments

Carrot is a seasonal perishable tuberous root vegetable which presents a preservation challenge owing to its elevated moisture content. Recently, carrot processing has received more attention because of its many health-promoting qualities and the reduction of postharvest losses in a cost-effective safe way. This study was designed to sort out the effective solar drying technique including pre-treatment that would retain the color and quality characteristics of dehydrated carrot. Carrot slices were subjected to dry using open sun drying (D1), solar drying long chimney (D2), solar drying short chimney (D3) and box solar drying (D4) techniques with the pretreatments of ascorbic acid 1 % (C3), citric acid 5 % (C4), potassium metabisulfite 1 % (C5) and potassium sodium tartrate 0.3 % (C6) before drying. Drying characteristics, nutritional attributes, phytochemicals and antioxidant of the dehydrated carrot samples were compared with the fresh sample and untreated (control) sample. Results showed that D4 was a good drying method to preserve nutritional quality with good appearance. Among the pretreatments, C5 and C4 resulted improved nutritional quality retention, enhanced visual acceptability and enriched antioxidant activities. PCA (Principal Component Analysis) and correlation matrix revealed that D4 with C5 retained the maximum amount of vitamin, minerals, total phenolic content, antioxidant and admirable dehydrated carrot color by inactivating enzymatic reaction. Therefore, box solar drying with potassium metabisulfite pretreatment would be very promising for functional carrot drying retaining acceptable color and nutrition composition.

Bioactive Compounds and Health-Promoting Properties of Elephant Apple (Dillenia indica L.): A Comprehensive Review

Elephant apple (Dillenia indica L.) grows wild in Southeast Asia's forests, including in China, India, Nepal, Bangladesh, and Sri Lanka. Elephant apples are considered essential fruit crops because of their high nutritional value, which includes high levels of vitamin C, carbohydrates, fats, fibre, protein, minerals, and fatty acids. It is important to understand the nutritional value and health benefits of elephant apples in order to increase fruit intake in people's daily diets. The present review paper focuses on elephant apple's phytochemistry, bioactive compounds, therapeutic value, and medicinal capabilities for designing and developing a wide range of food formulations. Proteins, minerals, fats, crude fibre, carbohydrates, vitamin C, tannins, malic acid, and glucose are abundant in the leaves, bark, and fruit of the elephant apple. In addition to nutritional components, many phytochemicals found in elephant apples have been identified as bioactive compounds with a broad range of biological activities, the most prominent of which are antioxidant, anticancer, antidiabetic, and anti-inflammatory properties. Overall, elephant apple is a rich, natural source of bioactive compounds with potential applications in the production of value-added foods and nutraceuticals for disease prevention and management.

Effect of Temperatures on Drying Kinetics, Extraction Yield, Phenolics, Flavonoids, and Antioxidant Activity of Phaleria macrocarpa (Scheff.) Boerl. (Mahkota Dewa) Fruits

Phaleria macrocarpa (Scheff.) Boerl. or 'Mahkota Dewa' is a popular plant found in Malaysia as it is a valuable source of phytochemicals and therapeutic properties. Drying is an essential step in the storage of P. macrocarpa fruits at an industrial level to ensure their availability for a prolonged shelf life as well as preserving their bioactive compounds. Hence, this study evaluates the effect of different temperatures on the drying kinetics, extraction yield, phenolics, flavonoids, and antioxidant activity of P. macrocarpa fruits. The oven-drying process was carried out in this study at temperatures of 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C. Six thin-layer drying models (i.e., Lewis, Page, Henderson and Pabis, two-term exponential, Logarithmic, and Midilli and Kucuk models) were evaluated to study the behaviour of oven-dried P. macrocarpa fruits based on the coefficient of determination (R2), root mean square error (RMSE), and chi-square (χ2). The quality of the oven-dried P. macrocarpa fruits was determined based on their extraction yield, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (2,2-diphenyl-1-picrylhydrazyl) using ultrasound-assisted extraction. The results showed that the time for moisture removal correspondingly increased in the oven-dried P. macrocarpa fruits. Apparently, the Midilli and Kucuk model is the most appropriate model to describe the drying process. The range of effective moisture diffusivity was 1.22 × 10-8 to 4.86 × 10-8 m2/s, and the activation energy was 32.33 kJ/mol. The oven-dried P. macrocarpa fruits resulted in the highest extraction yield (33.99 ± 0.05%), TPC (55.39 ± 0.03 mg GAE/g), TFC (15.47 ± 0.00 mg RE/g), and DPPH inhibition activity (84.49 ± 0.02%) at 60 °C based on the significant difference (p < 0.05). A strong correlation was seen between the antioxidant activity, TPC, and TFC in the oven-dried P. macrocarpa fruits. The current study suggests that the oven-drying method improved the TPC, TFC, and antioxidant activity of the P. macrocarpa fruits, which can be used to produce functional ingredients in foods and nutraceuticals.

Impact of Different Drying Methods on the Phenolic Composition, In Vitro Antioxidant Activity, and Quality Attributes of Dragon Fruit Slices and Pulp

The aim of this study was to compare the refractance window drying method (RWD) with the hot air oven drying (HD), vacuum drying (VD), and freeze-drying (FD) methods in order to analyze the outcomes of the qualitative properties of dragon fruit slices and pulp. Moreover, the impact of temperature on the phenolic content, antioxidant activity, color, and texture of the dragon fruit slices and pulp were studied. The results showed that the RWD samples exhibited a high nutritional quality in contrast to the other drying methods. The RWD method had a short drying time of 960 min to reach the final moisture content of 6.50% (dry basis), while the FD, VD, and HD methods had significantly higher drying times of 1320, 1200, and 1080 min, respectively, to reach the final moisture content. Higher values of TPC (182 mg GAE/100 g) and crude fiber (0.98%) were obtained in the RWD dragon fruit samples, indicating the potential of RWD to preserve the quality of dried samples. In conclusion, this study revealed that RWD provides an appropriate drying temperature as an alternative to freeze-drying. RWD may improve dragon fruit drying, adding value to the food industry.

Improving Drying Characteristics and Physicochemical Quality of Angelica sinensis by Novel Tray Rotation Microwave Vacuum Drying

In order to improve the shortcomings of uneven heating of traditional microwave drying and to maximally maintain food quality after harvest, a rotary microwave vacuum drying equipment was fabricated and used for drying experiments on Angelica sinensis to explore the effects of drying temperature, slice thickness, and vacuum degree on drying characteristics, physicochemical quality, and microstructure of dried Angelica sinensis products. The results showed that microwave vacuum drying can significantly shorten the drying time and improved the drying efficiency. Six different mathematical models were investigated and the Midilli model was the best-fitted model for all samples (R2 = 0.99903, Pearson’s r = 0.99952), and drying methods had various effects on different indexes and were confirmed by Pearson’s correlation analysis and principal component analysis. The optimal process parameters for microwave vacuum drying of Angelica sinensis were determined by entropy weight-coefficient of variation method as 45 °C, 4 mm, −0.70 kPa. Under this condition, well preserved of ferulic acid, senkyunolide I, senkyunolide H, ligustilide, total phenols and antioxidant activity, bright color (L* = 77.97 ± 1.89, ΔE = 6.77 ± 2.01), complete internal organizational structure and more regular cell arrangement were obtained in the samples. This study will provide a theoretical reference for the excavation of the potential value and the development of industrial processing of Angelica sinensis.

In vitro gastrointestinal digestion studies on total phenols, flavonoids, anti-oxidant activity and vitamin C in freeze-dried vegetable powders

In the present research study, the impact of digestion process on the levels of total phenols, flavonoids, vitamin C as well as anti-oxidant activity in freeze dried powders of mustard greens (MG) and roselle leaves (RL) was investigated. In addition, physicochemical and functional properties of MG and RL samples also evaluated. The digestion of freeze-dried vegetable powders was achieved through in vitro digestive procedure using various enzymes. From the study, it was observed that the digestion process increased the availability of phenols in both powders, where the digested vegetable powders possessed higher levels of total phenols and flavonoids. In contrast, the levels of vitamin C and anti-oxidant activity of vegetable powders (MG & RL) was found to be decreased minimally. Our research study suggests that in vitro digestion could enhance the TPC and TFC in mustard greens and roselle leaves. Therefore, MG and RL can be considered as a functional ingredient in the development of new products with better nutritional and functional characteristics. Further, the data on the physicochemical, functional and bioactive compounds in MG and RL may be used as reference for the enhancement of quality of products developed from MG and RL.

Effects of pre-drying treatments combined with explosion puffing drying on the physicochemical properties, antioxidant activities and flavor characteristics of apples

The purpose of this research was to study the effect of hot air drying, microwave vacuum drying and freeze drying combined with explosion puffing drying (HDEPD, MDEPD and FDEPD) on physicochemical properties, antioxidant activities and flavor characteristics of apples. The results showed that MDEPD and FDEPD products had better color and textural properties, exhibited a homogeneous porous structure. MDEPD and FDEPD better preserved scavenging abilities of DPPH, hydroxyl radical and FRAP, retained values of TFC and TPC. Aroma characteristics and taste properties of apples obviously changed with different drying methods, and drying qualities of products could be classified in terms of volatile compounds and taste profiles. Two principal components were able to describe 90.12% and 69.43% of the total volatile compound variance and total taste profile variance, respectively. Three main clusters of dried apples were identified, MDEPD and FDEPD can be used to enhance drying qualities of apple products.