RESUMEN
The aim of this study was to develop a star fruit extract (SFE) and incorporate it into aerogels based on native and phosphorylated potato starches. The phosphorylation of starch enhances its properties by incorporating phosphate groups that increase the spaces between starch molecules, resulting in a more resilient, intact aerogel with enhanced water absorption. The bioactive aerogels based on potato starch and 10, 15, and 20 % (w/w) of SFE were characterized by their morphological and thermogravimetric properties, infrared spectra, water absorption capacity, loading capacity, and antioxidant activity. Epicatechin was the major compound present in SFE. The thermal stability of SFE increased when incorporated into phosphorylated starch aerogels at a concentration of 20 %. The water absorption capacity was higher in phosphorylated starch aerogels (reaching 1577 %) than in their native counterparts (reaching 1100 %). Native starch aerogels with 15 and 20 % SFE exhibited higher antioxidant activity against hydroxyl free radicals compared to phosphorylated starch aerogels, achieving 79.9 % and 86.4 % inhibition for the hydroxyl and nitric oxide radicals, respectively. The ideal choice of freeze-dried aerogel depends on the desired effect, either to act as an antioxidant agent by releasing bioactive compounds from SFE or as a water-absorbent agent in food products.
Asunto(s)
Antioxidantes , Frutas , Geles , Extractos Vegetales , Solanum tuberosum , Almidón , Solanum tuberosum/química , Geles/química , Extractos Vegetales/química , Extractos Vegetales/farmacología , Almidón/química , Fosforilación , Antioxidantes/química , Antioxidantes/farmacología , Frutas/química , Averrhoa/química , Agua/químicaRESUMEN
Formic acid is utilized to induce esterification and chemical gelatinization in starch, particularly in the fabrication of electrospun fibers for nanomaterial production. This study investigated the impact of different concentrations (15, 20, 25, and 30 %) of cassava starch and formic acid as a solvent on the characteristics of the resultant polymeric solutions and electrospun fibers. Morphology, size distribution, thermogravimetric properties, diffraction patterns, and relative crystallinity were evaluated for the electrospun fibers. The amylose content of starch varied from 16.5 to 23.7 %, decreasing with esterification, achieving a degree of substitution of approximately 0.93. The solution-rheology exhibited elastic behavior, with viscosity increasing as starch concentration increased, hindering the fabrication of fibers at 25 and 30 % starch. Successful electrospun fibers were formed using 15 % and 20 % starch, displaying homogeneous morphologies with mean diameters of 165 nm and 301 nm, respectively. Esterification influenced thermogravimetric properties, leading to fibers with reduced degradation temperatures and mass loss compared to native starches. The electrospun fibers presented an amorphous structure, indicating a drastic reduction in relative crystallinity from 35.2 % in native starch to 8.5 % for esterified starches. This study highlights the intricate relationship between starch concentration, esterification, and solution viscosity, affecting the electrospinnability and properties of starch-polymeric solutions.
Asunto(s)
Formiatos , Manihot , Almidón , Manihot/química , Esterificación , Formiatos/química , Almidón/química , Viscosidad , Amilosa/química , Reología , TermogravimetríaRESUMEN
Onion is rich in bioactive and volatile compounds with antioxidant activity. However, the pungent odor of volatile compounds (VOCs) released restricts its use. The encapsulation of red onion extract by electrospinning is an alternative to mask this odor and protect its bioactive compounds. The main objective of this study was to encapsulate red onion bulb extract (ROE) in different concentrations into zein nanofibers by electrospinning and evaluate their thermal, antioxidant, and hydrophilicity properties. The major VOC in ROE was 3(2H)-furanone, 2-hexyl-5-methyl. Incorporating ROE into the polymeric solutions increased electrical conductivity and decreased apparent viscosity, rendering nanofibers with a lower average diameter. The loading capacity of ROE on fibers was high, reaching 91.5% (10% ROE). The morphology of the nanofibers was random and continuous; however, it showed beads at the highest ROE concentration (40%). The addition of ROE to the nanofibers increased their hydrophilicity. The nanofibers' antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl, nitric oxide, and hydroxyl radicals ranged from 32.5% to 57.3%. The electrospun nanofibers have the potential to protect and mask VOCs. In addition, they offer a sustainable alternative to the synthetic antioxidants commonly employed in the food and packaging industry due to their antioxidant activities.
Asunto(s)
Nanofibras , Zeína , Cebollas , Antioxidantes , Interacciones Hidrofóbicas e Hidrofílicas , Extractos VegetalesRESUMEN
Pinhão is highly perishable due to its high water activity, being easily affected by fungi during storage and also susceptible to infestation by larvae. This seed is usually marketed in the pinhão cones itself, or bulk threshed, and packed in plastic bags, chilled or ground frozen. Pinhão conservation and industrialization techniques should be developed to promote its commercialization and consumption at other times of the year, besides the seasonal period, encouraging its sustainable production, extraction and commercialization, considering its essentially extractive character. The objective of this study was to evaluate the conservation of pinhão by the use of gamma radiation and refrigeration. The pinhões were irradiated with a cobalt60 source at a dose rate of 1 kGy. A non-irradiated sample was used as a control. The pinhões were packed in high-density polyethylene bags and stored at ambient temperature and refrigerated at 4 ºC, during 90 days. Pinhões were evaluated for weight loss, acidity, reducing sugars, vitamin C, firmness, color, total phenolic compounds, antioxidant activity and microbiological analyzes. The isolated use of gamma radiation was not effective for the maintenance of the evaluated parameters. However, when used in conjunction with refrigerated storage, it reduced the growth of aerobic fungi, as well as mesophilic and psychrotrophic microorganisms. The isolated use of refrigeration showed a reduction in weight loss, reducing sugars and an increase in vitamin C content and antioxidant activity. Thus, to increase the benefits, we suggest evaluating higher doses of radiation as a function of the thick pinhão shell.
Asunto(s)
Radiación Ionizante , Refrigeración , Conservantes de Alimentos , Araucaria , SemillasRESUMEN
This study aimed to produce soluble potato starch ultrafine fibers for the encapsulation of pinhão coat extract (PCE), evaluating their relative crystallinity (RC), thermal stability, antioxidant activity, antimicrobial activity against Escherichia coli and Staphylococcus aureus, as well as in vitro biological digestion. In the simulation of in vitro biological digestion, the phenolic compounds release profile was also evaluated. The ultrafine fibers were produced by electrospinning, based on a polymeric solution composed of soluble potato starch (50% w/v) and formic acid. Then, PCE was incorporated at various concentrations (0.5%, 1.0%, and 1.5%, w/w, dry basis). The endothermic event of free PCE was not observed in the ultrafine fibers, which suggests its encapsulation. The RC decreased according to the increase in PCE concentration in the ultrafine fibers. The PCE resisted thermal treatments when encapsulated into the ultrafine fibers (100 and 180°C), and the ultrafine fibers with 1% PCE presented the highest amount of preserved phenolic compounds. Regarding antioxidant activity, the free PCE presented 85% of DPPH inhibition and the ultrafine fibers had 18% inhibition, not differing among the PCE concentrations (p < 0.05). The free PCE and the ultrafine fibers with 0.5% PCE showed inhibitory effect against S. aureus and the ones with 1.5% PCE showed controlled release of phenolic compounds during the simulation of in vitro digestion. Starch ultrafine fibers showed potential to be applied in food industries due to their capacity of protecting phenolic compounds when submitted to high temperatures or gastrointestinal conditions. Nevertheless, their application depends on the end use of the product. PRACTICAL APPLICATION: The encapsulation of pinhão coat extract (PCE) in ultrafine starch fibers promotes greater preservation of phenolic compounds. Thus, it can be incorporated into different foods that are produced using the ultra-high temperature (UHT) process-at 135-145°C for 5 to 10 s, or some other equivalent time/temperature combination. Another possibility is the incorporation of ultrafine fibers in active packaging: compounds can migrate to food, improving sensory characteristics, increasing shelf life, preventing chemical and microbiological deterioration, and ensuring food safety.