Effectiveness of the fountain-microwave drying method in some selected pumpkin cultivars

Biofortified Sweet Potato Submitted to Different Domestic Cooking Processes: Impact on β-Carotene Retention and Antioxidant Capacity

Sweet potato (Ipomoea batatas) is a source of fiber, carbohydrates, minerals and phytochemicals such as carotenoids and phenolic compounds. Biofortification with provitamin A carotenoid improves the nutritional properties of sweet potatoes and can contribute to reducing the deficiency of this micronutrient, but cooking may affect its composition. In this context, this study aimed to evaluate the effect of seven different domestic cooking processes (deep frying, air frying, steaming, boiling, pressure cooking, baking, and microwave cooking) on the color, phenolic compounds, antioxidant activity, and real retention of β-carotene in biofortified sweet potatoes. The air frying was the process that promoted more remarkable changes on the color (p < 0.05). The air fryer was the most recommended domestic processes for maintaining phenolic compounds and antioxidant capacity, while the oven was the least recommended method (p < 0.05). Pressure cooking and boiling were the most recommended methods for greater β-carotene real retention, whereas air fryer resulted in the greatest β-carotene losses in biofortified sweet potatoes (p < 0.05). Different conventional cooking methods influence the degree of loss of phytochemicals present in biofortified sweet potatoes, which can impact the consumption of these nutrients, and the efficiency of the food biofortification program.

Effects of thermal processing on natural antioxidants in fruits and vegetables

Research on the content of polyphenolic compounds in fruits and vegetables, the extraction of bioactive compounds, and the study of their impact on the human body has received growing attention in recent years. This is due to the great interest in bioactive compounds and their health benefits, resulting in increased market demand for natural foods. Bioactive compounds from plants are generally categorized as natural antioxidants with health benefits such as anti-inflammatory, antioxidant, anti-diabetic, anti-carcinogenic, etc. Thermal processing has been used in the food sector for a long history. Implementing different thermal processing methods could be essential in retaining the quality of the natural antioxidant compounds in plant-based foods. A comprehensive review is presented on the effects of thermal blanching (i.e., hot water, steam, superheated steam impingement, ohmic and microwave blanching), pasteurization, and sterilization and drying technologies on natural antioxidants in fruits and vegetables.

Phenolic compounds and antioxidant activity in Cucurbita ficifolia fruits, an underrated fruit

The fruits and seeds of Cucurbita ficifolia Bouché are sources of minerals, vitamins, and functional compounds with nutraceutical and preventive potential against cardiovascular diseases and diseases derived from eating disorders. C. ficifolia is native from Mesoamerica and is currently cultivated in temperate zones from Mexico to South America and Asia. This study evaluated the fruit mesocarps of C. ficifolia for physicochemical parameters, antioxidant activity, and phenolic compound contents in a collection of farmers' landraces. Germplasm is cultivated by traditional farmers in the temperate zones of two municipalities from Oaxaca, Mexico. The results show that the content of soluble solid contents (SSC), pH, total sugars (TS), and flavonoids are influenced by the fruit geographical origin (municipalities) and implicitly by their agroecological cultivation conditions (Huamelúlpam: SSC = 6.22 °Brix, pH = 5.44, TS = 0.52 mg G g-1, flavonoids = 1.24 mg CE g-1; Yanhuitlán: SSC = 6.69, pH = 5.33, TS = 0.55, flavonoids = 1.30). Among populations preserved by traditional farmers, significant differences, and wide variability were found for all parameters evaluated (Huamelúlpam: SSC = 4.9-7.3, pH = 5.5-5.8, TS = 0.4-0.7, protein = 5.8-11.4, polyphenols = 1.9-4.8, flavonoids = 1.0-1.5, DPPH = 4.3-10.6, and FRAP = 4.8-11.8; Yanhuitlán: SSC = 4.3-8.9, pH = 4.8-5.6, TS = 0.4-0.7, protein = 5.0-15.3, polyphenols = 1.9-4.9, flavonoids = 0.8-1.9, DPPH = 5.3-10.5, and FRAP = 4.5-12.6). Eight compounds were identified by UPLC-MS: L-phenylalanine, an amino acid that is regularly associated with proteins; vanillin, a phenolic aldehyde with its functional groups including aldehyde, hydroxyl, and ether; and six phenolic acids: 4-hydroxybenzoic acid, 4-hydroxyphenylacetic acid, vanillic acid, 4-coumaric acid, ferulic acid, and salicylic acid, all with potential health effects. The C. ficifolia fruit mesocarp has bioactive compounds with high antioxidant activity with the potential to both improve diet and to obtain other benefits against nontransmissible diseases derived from food and its associated risk factors.

Quality retention in pumpkin powder dried by combined microwave-convective drying

Three distinct drying methods, microwave drying (MWD), convective drying (CVD) and microwave-convective drying (MWCVD) with a grinding process were applied to obtain pumpkin powder. The effects of CVD (60, 70 & 80 °C), MWD (100 & 200 W) and MWCVD (100 W-60 °C, 100 W-70 °C, 100 W-80 °C, 200 W-60 °C, 200 W-70 °C, and 200 W-80 °C) applications on the physicochemical properties (water activity, bulk, tapped & particle densities, porosity, flowability, cohesiveness, swelling capacity, water holding capacity and water solubility index), color values (L ^* , a ^* , b ^* , C, α ^o and Δe), bioactive compounds (5-Hydroxymethyl-2-furfural (HMF), total phenolic content (TPC) and antioxidant capacity (DPPH and ABTS)) of the eleven pumpkin fruit powders were compared. The MWCVD, namely pumpkin powders dried at 200 W-80 °C resulted in shorter drying times with high-quality dried pumpkin powders. The bulk, tapped and particle densities of pumpkin powders at 200 W-80 °C by MWCVD were 0.56, 0.66 and 1.74 g/cm³, respectively. These values are indicators of the good porosity (61.82%) of pumpkin powders. In addition, the highest TPC (1277.08 mg GA/100 g dw) and ABTS (126.99 ± 3.31 µmol Trolox/g dw) was observed for microwave-convective dried pumpkin powders at 200 W-80 °C. On the other hand, the lowest HMF level (10.12 ± 1.78 mg/kg dw) was found for the pumpkin poowders dried by MWCVD at 200 W-80 °C. In overall, dried pumpkin powders by a MWCVD method can be employed to acquire a high-quality food material along with an enhanced physicochemical properties, color and bioactive components.

The hypoglycemic and regenerative effect of the pancreas using instant porridge mix of pumpkin and brown rice flour on diabetic rats

Diabetes is a congenital disease resulting from inefficiencies in insulin production and activities. Instant porridge mixed with pumpkin and brown rice (instant porridge mix) can be a functional food to lower blood sugar. This study aimed to determine the hypoglycemic activity and the ability of instant porridge mix to regenerate pancreatic beta cells in diabetic rats. Diabetes was induced by Streptozotocin (STZ). Instant porridge mix was used to substitute the standard feed AIN-93 at 0, 10, 20, and 30% levels. The hypoglycemic activity test used 30 Sprague Dawley rats assigned to five groups with six each. The groups were (1) normal rats fed with standard feed AIN-93, (2) DM/diabetes mellitus rats fed with AIN 93 feed, (3) DM rats fed with 10% instant porridge mix, (4) DM rats fed with 20% instant porridge mix, and (5) DM rats fed with 30% instant porridge mix. The treatment was carried out for twenty-eight days, and blood sampling was carried out at seven-day intervals for blood analysis to determine glucose levels. At the end of the study, the levels of MDA (malondialdehyde) and blood glucose in the liver of the rats were also analyzed. A histopathology test was also done on the pancreas. The results showed that feed substitution (20%) with instant porridge mix significantly (p <0.05) reduced the level of blood glucose from 271.81 to 99.66 mg.dL-1 in DM rats. In conclusion, DM rats fed with 20% instant porridge mix were the best treatment for hypoglycemic and regenerative effects of the pancreas.

Nutritional Properties and In Vitro Antidiabetic Activities of Blue and Yellow Corn Extracts: A Comparative Study

The objective of this research was to designate and identify the profile of fatty acids, sterols, and polyphenol compounds and to demonstrate the antidiabetic activity, in blue corn extracts (BCE) in comparison with the yellow variant of this raw material. All of the maize lines, including the blue corn, were grown in Europe (southwestern part of Poland) and not in the place of origin (South America). In the extracts of the blue corn variety, eight anthocyanin compounds were isolated. The compound found in the largest amount was pelargonidin, followed by cyanidin-3-glucoside and other glycoside derivatives. Unsaturated fatty acids were the main ones found in the lipid fraction of blue and yellow corn, including linoleic acid and oleic acid. Saturated fatty acids, such as stearic and palmitic acid, were present in smaller amounts. The blue corn’s sterol profile was similar to other varieties of this corn, with β-sitosterol and campesterol occurring in the largest amount, alongside smaller amounts of stigmastanol and stigmasterol. The blue corn variety was characterized by a high content of polyphenolic compounds, which show several biological activities, including antidiabetic activity. The strongest in vitro antidiabetic effect was found in the blue corn lines. Among the polyphenolic compounds in both the blue and yellow corn varieties, in the largest amounts, were caffeic acid, procyanidin B2, and gallic acid. Despite the known and proven biological activity of polyphenolic compounds, the fat fraction showed the highest in vitro antidiabetic activity in the BCE studied.

Could fruits be a reliable source of food colorants? Pros and cons of these natural additives

Color additives are important for the food industry to improve sensory quality lost during food process and to expand the variety of products. In general, artificial colorants have lower cost and better stability than the natural ones. Nevertheless, studies have reported their association with some health disorders. Furthermore, consumers have given greater attention to food products with health beneficial effects, which has provided a new perspective for the use of natural colorants. In this context, fruits are an excellent alternative source of natural compounds, that allow the obtainment of a wide range of colorant molecules, such as anthocyanins, betalains, carotenoids, and chlorophylls. Furthermore, in addition to their coloring ability, they comprise different bioactive properties. However, the extraction and application of natural colorants from fruits is still a challenge, since these compounds show some stability problems, in addition to issues related to the sustainability of raw-materials providing. To overcome these limitations, several studies have reported optimized extraction and stabilization procedures. In this review, the major pigments found in fruits and their extraction and stabilization techniques for uses as food additives will be looked over.

Effect of Different Drying Techniques on Dehydration Kinetics, Physical Properties, and Chemical Composition of Lemon Thyme

Lemon thyme contains several bioactive health-promoting compounds of high antioxidant capacity—such as polyphenols, carotenoids, and chlorophyll—which may undergo degradation during drying in incorrect processing conditions. This work is aimed at evaluating the impacts of different drying techniques and parameters on the chemical and physical properties of lemon thyme. In the experiment, lemon thyme leaves are dried using two traditional hot-air methods, convective drying (temperature 70°C or 80°C, air velocity 2 m/s), and fluidized bed drying (temperature 70°C or 80°C, air velocity 5–10 m/s); as well as two innovative drying methods, microwave-assisted fluidized bed (MFB) drying (microwaves at a power of 240 or 440 W, air temperature 40°C, air velocity 5–10 m/s) and microwave-vacuum (MV) drying (microwaves at a power of 240 or 440 W, under vacuum at 4–6 kPa). The kinetics of water delivery are described using the Page Model. After drying, the nutritional composition of the material is analyzed: polyphenol (total content and polyphenols profile by ultra-performance liquid chromatography), carotenoid, and chlorophyll total content, as well as antioxidant capacity (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt [ABTS+] and ferric reducing antioxidant power [FRAP]). Color changes ( L*, a*, b*, ΔE) are also analyzed using the visible effects of lemon thyme pigment disintegration. It is found that the MV drying method is the best for lemon thyme preservation, as it has the shortest process time and the highest retention of polyphenols (78.90%-82.14%), chlorophylls (51.54%-52.68%), antioxidant capacity (47.83%-48.63% of ABTS+ and 20.85%-45.45% of FRAP), and presented the least color change ( ΔE = 25.57-28.32). For preserving carotenoids, the most protective method is MFB (retention 68.46%-70.61 %).

Incorporation of microencapsulated hydrophilic and lipophilic nutrients into foods by using ultrasound as a pre-treatment for drying: A prospective study

The present work proposes using the ultrasound technology to incorporate microencapsulated nutrients during pre-treatments for drying of food products. Both hydrophilic and lipophilic nutrients were evaluated: incorporation of microcapsules of iron (obtained by spray drying using maltodextrin as wall material) and carotenoids (obtained by hot emulsification and solidification using hydrogenated palm oil as wall material). The ultrasound pre-treatment was applied in water and ethanol, where the microcapsules were dispersed, and food samples were immersed. Pumpkin and apple were selected as suitable food material to perform the iron and carotenoid incorporation, respectively. Ultrasound allowed more homogeneous iron incorporation in pumpkin. The iron content increased more than 1000% in pre-treated samples compared to control. In the same manner, carotenoid content increased in about 430% when ultrasound was applied. After drying, the carotenoid content decreased by 65% in control samples. However, better carotenoid retention was obtained after drying in ultrasound processed samples. The results show that pre-treatment with ultrasound can be used to incorporate nutrients into the food matrix, increasing not only the incorporated quantity but also promoting their preservation. Nevertheless, future studies must be performed to determine the nutrient bioavailability and bioaccessibility.

Effects of high hydrostatic pressure on physico-chemical and structural properties of two pumpkin species

The effects of high pressure treatments (200, 400, 600 MPa for 5 min) and a thermal treatment (85 °C for 5 min) were evaluated on cubes of two pumpkin species (Cucurbita maxima L. var. Delica and Cucurbita moschata Duchesne var. Butternut) up to 2 months of refrigerated storage. Increasing the pressure, small parenchyma cells from the pumpkin tissue exhibited collapses and separations, especially for Butternut. This species showed a lower hardness than Delica at time 0. For both species, 400 MPa and thermal treatment were the most effective in the inactivation of pectinmethylesterase, which reactivated after 2 months, especially for Butternut. Colorimetric parameters decreased after all treatments. Antioxidant activity resulted affected by pressure, showing a significant increase during storage especially for the samples treated at 200 MPa after 2 months, comparable to the thermal treated ones. Among the tested treatments, 400 MPa may be considered as the best option for the quality retention during storage.

The Influence of Vacuum Impregnation on Nutritional Properties of Fluidized Bed Dried Kale (Brassica oleracea L. Var. Acephala) Leaves

The aim of the work was to assess the possibility of obtaining high bioactivity dried kale using a vacuum impregnation as the preliminary processing before the drying. Kale leaves underwent vacuum impregnation in freshly squeezed onion juice and in sodium chloride solution utilising the following impregnation process parameters: At the vacuum stage, 6 kPa reduced pressure for 1 min, dosing the impregnating solution and keeping the sample under vacuum for 2 min, and then 6 min in impregnating solution at atmospheric pressure. Fluidized bed drying of kale was conducted using inert polypropylene balls, utilising a drying air temperature in a range from 70 to 130 °C. The drying kinetics were described, and the dehydrated product’s quality was assessed, on the basis of these selected characteristics: The content of chlorophylls, polyphenols and carotenoids, and antioxidant activity measured with ABTS⁺, dry matter, water activity and colour. It was determined that protective influence of vacuum impregnation before fluidized bed drying was seen only in the case of using temperatures of 90 and 110 °C. The highest content of bioactive components in dried kale was obtained in the case of using onion juice impregnation and drying at 110 °C.

The Effect of Selected Fruit Juice Concentrates Used as Osmotic Agents on the Drying Kinetics and Chemical Properties of Vacuum-Microwave Drying of Pumpkin

The study examined the osmotic dehydration of pumpkin slices in chokeberry, flowering quince, and raspberry concentrated juices. Products obtained were subjected to vacuum-microwave finish drying (VMD). The objective of the study was to evaluate the drying kinetics and the chemical properties, that is, total polyphenolics content and antioxidant capacity of the vacuum-microwave-dried pumpkin products. The concentration and temperature of the juices were 40°Brix and 45°C, respectively. The pumpkin slices were pretreated in concentrated juices for 0.5, 1, 2, 3, and 6 hours. Vacuum-microwave finish drying was carried out at the power of magnetrons that ensured the maintenance of the safe temperature (below 90°C) of the slices measured with the use of infrared camera. The results of the study showed that the moisture content of samples during the pretreatment in concentrated juices was decreasing until the equilibrium stage. The logarithmic model was used to describe the drying kinetics of pumpkin during VMD. Osmotic pretreatment resulted in a decrease in colour coordinates, improved the antioxidant activity of dried product, and prolonged the duration of VMD.