Physical properties, resistant starch content and antioxidant profile of purple sweet potato powder after 12 months of storage

Elevating anthocyanin extraction from mangosteen pericarp: A comparative exploration of conventional and emerging non-thermal technology

Mangosteen pericarp (MP) is abundant in bioactive compounds but is often discarded as waste, leading to environmental pollution. This study compared the extraction of dried MP using maceration and high-pressure processing (HPP). HPP at 10 min (500 MPa/20 °C) resulted in the highest ACNs, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities. It also significantly reduced residual enzyme activities (REA) of polyphenol oxidase (PPO) and peroxidase (POD) by 33.90 % and 8.27 %, respectively. Fourier-transform infrared spectroscopy (FT-IR) analysis revealed a new wavelength at 2665.25 cm-1, and scanning electron microscopy (SEM) showed significant pore formation in MP cells, indicating cell damage. HPP-10 min enhanced the extraction of bioactive compounds, which significantly elevated the thermal stability of ACNs at 60 °C. This suggests that HPP is a promising method for extracting and preserving ACNs and other bioactive compounds from dried MP, with potential applications as natural colorants.

Colourful staples on your table: Unus ex genere suo

The positive health benefits of colored staples have led to a significant increase in interest in them as healthy food ingredients. Numerous in vitro and in vivo studies have demonstrated that colored cereals are rich in antioxidants, carotenoids, and xanthophylls, which are widely used as natural additives in the food industry. Additionally, shifts in consumer preferences have led to a preference for nutritionally balanced diets over traditional high-energy ones. Thus, colored cereals offer additional nutritional value that has been previously untapped. Besides providing essential nutrients, these natural pigments also have the potential to replace synthetic colors and food additives. This review aims to provide insights into the nutritional value of various colored staples compared to conventional starchy staples and their associated health benefits. Colored staples can be incorporated into daily diets, offering a nutritious and healthful addition to the table.

Influence of Different Drying Methods on Anthocyanins Composition and Antioxidant Activities of Mangosteen (Garcinia mangostana L.) Pericarps and LC-MS Analysis of the Active Extract

Mangosteen pericarps (MP) often end up as agricultural waste despite being rich in powerful natural antioxidants such as anthocyanins and xanthones. This study compared the effect of different drying processes and times on phenolic compounds and antioxidant activities of MP. Fresh MP were subjected to 36 and 48 h of freeze-drying (-44 ± 1 °C) and oven-drying (45 ± 1 °C), and 30 and 40 h of sun-drying (31 ± 3 °C). The samples were analyzed for anthocyanins composition, total phenolic content (TPC), total flavonoid content (TFC), antioxidant activities, and color characteristics. Analysis of liquid chromatography-mass spectrometry (LC-MS) with electrospray ionization identified two anthocyanins in MP: cyanidin-3-O-sophoroside and cyanidin-3-O-glucoside. Overall, the drying process, time, and their interactions significantly (p < 0.05) influenced the phenolic compounds, antioxidant activities, and color in MP extracts. Both freeze-drying after 36 h (FD36) and 48 h (FD48) possessed significantly (p < 0.05) higher total anthocyanins (2.1-2.2 mg/g) than other samples. However, FD36 was associated with significantly (p < 0.05) higher TPC (~94.05 mg GAE/g), TFC (~621.00 mg CE/g), and reducing power (~1154.50 μmol TE/g) compared to FD48. Moreover, FD36 is more efficient for industrial applications due to less time and energy consumption. Subsequently, obtained dried MP extracts could be further utilized as an alternative to synthetic food colorants.

Kidney Bean Substitution Ameliorates the Nutritional Quality of Extruded Purple Sweet Potatoes: Evaluation of Chemical Composition, Glycemic Index, and Antioxidant Capacity

The extrusion process may influence the nutritional profiles of carbohydrate-rich food ingredients, including the glycemic index (GI) and antioxidant capacity. This study aimed to evaluate the nutritional profile of extruded purple sweet potato (EPSP) substituted with kidney bean flour (KBF) (0, 30, and 40%). These foods were further characterized by their proximate composition, resistant starch, polyphenols, GI, and antioxidant capacities. The 40% KBF substitution enhanced the protein and fiber contents of the EPSP by up to 8% and 6%, respectively. Moreover, it also revealed that EPSP with 40% KBF substitution had a low-GI category (53.1), while the 0 and 30% substitution levels had a high-GI category, i.e., 77.4 and 74.7, respectively. However, the extrusion processing reduced the anthocyanin content and antioxidant capacity of purple sweet potato flour containing 40% KBF by 48% and 19%, respectively. There was a significant relationship between the GI values of proteins, fats, and fibers (p < 0.05). The insignificant effect of resistant starch and phenol contents on GI value was recorded due to the low concentrations of those components. KBF substitution could ameliorate the profile of protein, fiber, and GI, but not for antioxidant capacity. The other innovative processes for preserving antioxidant capacity might improve the product quality.

The Modelling of Convective Drying Variables’ Effects on the Functional Properties of Sliced Sweet Potatoes

Drying is a commonly used technology that provides a long post-harvest storage time for produce such as sweet potatoes. Convective drying (CD) is a method that, when conditions are optimized, provides produce with a better appearance and improved textural properties. In this study, changes in water activity (a_w), moisture content (MC), rehydration capacity (R_c), shrinkage (S_b) and color attributes were modelled for the optimization of drying factors (temperature, thickness and time) using response surface methodology (RSM). The total phenol content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC) and antioxidant activity of CD samples (63.79 °C, 4.78 h, 3 mm) were investigated as functional aspects and compared with results for FD samples (−45 °C, one term). Optimum convective drying conditions caused an increase in general antioxidant properties, such as total phenol (TPC), total anthocyanin (TAC), DPPH and CUPRAC. The TPC was 190.94 mgGAE/100 g, the DPPH scavenging activity was 12.05%, the TAC was 11.37 mg/100 g, and the CUPRAC was 0.469 mmolTR/g in convectively dried samples under optimum conditions. Although improved appearance and textural properties are obtained by freeze drying, it is possible to produce sweet potatoes with good appearance and functional properties by optimizing the variables of the convective drying process.

Optimization of the Drum Drying Parameters and Citric Acid Level to Produce Purple Sweet Potato (Ipomoea batatas L.) Powder Using Response Surface Methodology

Purple sweet potato (PSP) is a rich source of anthocyanins, but the anthocyanin content and color can be affected by the drying method and processing condition. Response surface methodology (RSM) with a Box-Behnken design (BBD) was used to investigate the effects of citric acid (CA) concentration, steam pressure (SP) and rotation speed (DS) on the physicochemical and functional properties of drum-dried purple sweet potato powder (PSPP). The anthocyanins of the PSPP were analyzed using mass spectrometry with electrospray ionization and twelve anthocyanins were identified. The results indicated that the moisture content (4.80 ± 0.17-9.97 ± 0.03%) and water activity (0.290 ± 0.004-0.47 ± 0.001) (p < 0.05) decreased with increasing drum temperature as well as with reduced drum rotating speed. CA had a significant (p < 0.05) effect on the color and total anthocyanin content (101.83 ± 2.20-124.09 ± 2.89 mg/100 g) of the PSPP. High SP and low DS negatively affected the antioxidant properties of the PSPP. DPPH value of the PSPP ranged from 20.41 ± 0.79 to 30.79 ± 1.00 μmol TE/g. The optimal parameters were achieved at 0.59% CA, 499.8 kPa SP and 3 rpm DS.

Grown to be Blue-Antioxidant Properties and Health Effects of Colored Vegetables. Part I: Root Vegetables

During the last few decades, the food and beverage industry faced increasing demand for the design of new functional food products free of synthetic compounds and artificial additives. Anthocyanins are widely used as natural colorants in various food products to replenish blue color losses during processing and to add blue color to colorless products, while other compounds such as carotenoids and betalains are considered as good sources of other shades. Root vegetables are well known for their broad palette of colors, and some species, such as black carrot and beet root, are already widely used as sources of natural colorants in the food and drug industry. Ongoing research aims at identifying alternative vegetable sources with diverse functional and structural features imparting beneficial effects onto human health. The current review provides a systematic description of colored root vegetables based on their belowground edible parts, and it highlights species and/or cultivars that present atypical colors, especially those containing pigment compounds responsible for hues of blue color. Finally, the main health effects and antioxidant properties associated with the presence of coloring compounds are presented, as well as the effects that processing treatments may have on chemical composition and coloring compounds in particular.