Bioactive aerogels based on native and phosphorylated potato (Solanum tuberosum L.) starches incorporated with star fruit extract (Averrhoa carambola L.).

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.

Antimicrobial activity of geranium (Pelargonium graveolens) essential oil and its encapsulation in carioca bean starch ultrafine fibers by electrospinning.

Geranium (Pelargonium graveolens) is known for being an aromatic plant rich in bioactive compounds with antibacterial properties. In this study, geranium essential oil (GEO) was extracted and encapsulated in ultrafine bean starch fibers produced by electrospinning as an antibacterial agent. GEO revealed a composition rich in volatile compounds, including citronellol, cis-geraniol, ß-linalool, citronellyl formate, and linalool formate. In its free form, GEO exhibited high antibacterial activity against pathogenic bacteria strains (L. monocytogenes, S. aureus, and E. coli). The bean starch fibers, produced with and without the addition of GEO, were uniform and continuous, with an average diameter ranging from 249 to 373 nm. Confocal analysis indicated a uniform distribution of GEO in the fibers, with a loading capacity of 54.0 %, 42.9 %, and 36.5 % for 20 %, 30 %, and 40 % GEO concentrations, respectively. Remarkably, fibers containing 40 % GEO showed a significant reduction in tested bacteria (L. monocytogenes, S. aureus, and E. coli), suggesting promising applications in preventing losses and extending the shelf life of food through active packaging.

Cassava starch esterification with formic acid for fabrication of electrospun fibers.

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.

Electrospun nanofibers based on zein and red onion bulb extract (Allium cepa, L.): Volatile compounds, hydrophilicity, and antioxidant activity.

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.

Starch extraction from avocado by-product and its use for encapsulation of ginger essential oil by electrospinning.

Starches from alternative sources, such as avocado seed, have potential for application in the encapsulation of essential oils. This study aimed to extract starch from avocado seeds and its use as wall material to encapsulate ginger essential oil (GEO), at different concentrations. The fibers were produced by electrospinning and evaluated by morphology, size, infrared spectra, thermogravimetric properties, contact angle, loading capacity, and antibacterial activity. The major compounds in GEO were α-zingiberene, ß-sesquiphellandrene, α-farnesene, and α-curcumene. The starch-GEO fibers presented a higher diameter (∼553 nm) than those without GEO (345 nm). Encapsulation of GEO in starch fibers increased their thermal degradation temperatures from 165.8 °C (free GEO) to 257.6 °C (40 % GEO fibers). The starch-GEO fibers presented characteristic bands of their constituents by infrared spectra. Loading capacity ranged from 44 to 54 %. The fibers showed hydrophilic character, with a contact angle of <90°. Free GEO and the fibers with 50 % of GEO displayed antibacterial activity against Escherichia coli, proving the bioactivity of the starch-GEO fibers and its possible applicability for food packaging. Avocado seed starch showed to be a great wall material for GEO encapsulation.

Oleogels based on germinated and non-germinated wheat starches and orange essential oil: Application as a hydrogenated vegetable fat replacement in bread.

This study aimed to produce oleogels based on non-germinated and germinated wheat starches with orange essential oil, apply them to replace hydrogenated vegetable fat in bread, and assess the antifungal action. The oleogels were prepared using sunflower oil, wheat starches, beeswax, water, and orange essential oil (OEO). They were evaluated to determine the volatile compounds, oil binding capacity, texture profile, storage stability for 20 days, thermogravimetric analysis, and functional groups. The breads were evaluated by their moisture content, specific volume, texture profile, volatile compounds, and microbiological contamination during 15 days of storage. The oleogels showed high storage stability, were fully intact after 20 days of storage, and had a high oil binding capacity (∼100 %). The oleogels with OEO presented increased adhesiveness and reduced hardness compared to the ones without essential oil. The oleogels with OEO based on germinated wheat starch released a high amount of volatile compounds. Substituting saturated vegetable fat with oleogels in bread formulation resulted in decreased hardness and maintained specific volume. Furthermore, incorporating OEO oleogels in the bread led to reduced growth of total mesophiles and fungi.

Absorbent bioactive aerogels based on germinated wheat starch and grape skin extract.

This study aimed to produce water-absorbent bioactive aerogels using biodegradable raw materials, wheat starch and poly ethylene oxide (PEO), and derived from agro-industrial residues (grape skin) obtained in the wine industry. The aerogels were produced using germinated wheat starch (GWS), with and without PEO, and incorporating grape skin extract (GSE) at concentrations of 5 and 10 % (w/w). The GSE was evaluated for total and individual phenolic compounds, anthocyanins, and antioxidant activity. The starch aerogels were characterized for morphology, density, porosity, functional groups by FT-IR, relative crystallinity and diffraction pattern, water absorption capacity, antioxidant activity, and in vitro release profile of phenolic compounds in food simulant medium. The total phenolic compounds in GSE was 226.25 ± 0.01 mg equivalent of gallic acid/g GSE. The aerogels showed low density and high porosity. All aerogels demonstrated high water absorption capacity (581.4 to 997.5 %). The antioxidant activity of the aerogels increased with increasing GSE concentration and the addition of PEO. The aerogels could release GSE gradually for up to 120 days in the hydrophilic simulant medium and 240 h for the hydrophobic medium. Starch-based aerogels with GSE showed potential to be applied as exudate absorbers with antioxidant activity to develop active food packaging.

Red onion skin extract rich in flavonoids encapsulated in ultrafine fibers of sweet potato starch by electrospinning.

Electrospinning encapsulation is a highly viable method to protect bioactive compounds and prevent their degradation. Hence, this study produced ultrafine fibers based on yellow and white sweet potato starches and a red onion skin extract (ROSE; 0, 3, 6, and 9 %, w/w) using electrospinning. The fibers were evaluated for morphology, thermogravimetric properties, antioxidant, in vitro release simulation, thermal resistance (100 and 180 °C), and wettability. The fibers with ROSE presented 251-611 nm diameters, 67-78 % loading capacity, and 51.6-95.4 and 13.4-99.4 % thermal resistance (100 and 180 °C, respectively); apigenin presented the highest thermal protection. The phenolic compounds showed low release using 10 % ethanol and greater release with 50 % ethanol. The fibers with 9 % ROSE showed 2,2'-azino-bis(3-ethylbenzothiazoline) 6-sulfonic acid radical inhibition above 92 %. The ultrafine fibers and the unencapsulated ROSE showed inhibitory action against Escherichia coli and Staphylococcus aureus; only unencapsulated ROSE showed bactericidal activity.

Curcumin encapsulation in capsules and fibers of potato starch by electrospraying and electrospinning: Thermal resistance and antioxidant activity.

The aim of this work was to encapsulate curcumin at different concentrations in capsules and fibers of native potato starch by electrospraying and electrospinning. The best conditions for the production of capsules and fibers were obtained by varying the polymer concentration and resting time of the polymer solution. The best conditions were used for the encapsulation of curcumin. The curcumin-loaded capsules and fibers had an average diameter of 1373 nm to 1787 nm and 108 nm to 142 nm, respectively, and had a high curcumin loading capacity with values ranging from 79.01 % to 97.09 %. Curcumin encapsulated in starch capsules and fibers showed higher thermal stability at 180 °C for 2 h compared to unencapsulated curcumin. The antioxidant activity of starch fibers containing 1 % of curcumin had the greatest ability to inhibit the ABTS radical (45 % inhibition). These materials are promising for use in food or active packaging.

Physical modification of starch by heat-moisture treatment and annealing and their applications: A review.

Heat-moisture treatment (HMT) and annealing are hydrothermal starch modifications. HMT is performed using high temperature and low moisture content range, whereas annealing uses excess of water, a long period of time, and temperature above the glass transition and below the gelatinization temperature. This review focuses on: research advances; the effect of HMT and annealing on starch structure and most important properties; combined modifications; and HMT-starch and annealed-starch applications. Annealing and HMT can be performed together or combined with other modifications. These combinations contribute to new applications in different areas. The annealed and HMT-starches can be used for pasta, candy, bakery products, films, nanocrystals, and nanoparticles. HMT has been studied on starch digestibility and promising data have been reported, due to increased content of slowly digestible and resistant starches. The starch industry is in constant expansion, and modification processes increase its versatility, adapting it for different purposes in food industries.

Pinhão coat extract encapsulated in starch ultrafine fibers: Thermal, antioxidant, and antimicrobial properties and in vitro biological digestion.

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.

Aerogels based on corn starch as carriers for pinhão coat extract (Araucaria angustifolia) rich in phenolic compounds for active packaging.

The objective of this study was to produce renewable aerogels from native and anionic corn starches loaded with pinhão coat extract (PCE) with water absorbent capacity, antioxidant activity and controlled release of phenolic compounds in a hydrophilic food simulant media. Starch aerogels were produced with different concentrations of PCE, 5 and 10%, and evaluated for FT-IR spectra, relative crystallinity, thermal properties, water absorption capacity (WAC), density, antioxidant activity and in vitro release. Thermal stability of the compounds was improved by the incorporation of PCE. The aerogels presented high WAC of 541 to 731% and low-density values of 0.03 g.cm-1. The highest inhibition of DPPH and ABTS radicals was presented to anionic starch aerogels with 10% PCE rendering 26% of inhibition of ABTS and 24% of DPPH. The maximum in vitro releases for native and anionic starch aerogels with 5% of PCE were 28.70 and 29.44%, respectively, and for aerogels with 10% of PCE they were 34.27 and 35.94%, respectively. The anionic starch aerogels had the highest amount of phenolic compounds released when compared to the native starch aerogels. The starch-based bioactive aerogels showed potential to be applied in food packaging as water absorbent and as a carrier of phenolic compounds.

Suitability of starch/carvacrol nanofibers as biopreservatives for minimizing the fungal spoilage of bread.

The objective of this study was to evaluate the in vitro susceptibility of fungi to starch/carvacrol nanofibers produced by electrospinning. The nanofibers were incorporated into bread dough or used in the development of active packages to minimize bread spoilage. In agar diffusion and micro-atmosphere assays, the nanofibers with 30 % or 40 % carvacrol presented inhibition zones with low growth and were effective inhibiting both the fungi evaluated in this work. The MICs for nanofibers with 30 % carvacrol were 0.098 and 9.8 mg/mL against Penicillium sp. and Aspergillus flavus, respectively; for the 40 % nanofibers, the MIC was 19.6 mg/mL against Aspergillus flavus. As for MFC, only the 30 % nanofibers exerted fungicidal effect. The treatments administered directly to the bread dough had low colony-forming unit. For bioactive packages, nonwovens with 30 % carvacrol were effective in preventing bread spoilage. Thus, nanofibers are a good alternative to chemical additives or bioactive packages in food industry.

Physically cross-linked aerogels based on germinated and non-germinated wheat starch and PEO for application as water absorbers for food packaging.

The objective of this study was to generate and characterize physically cross-linked aerogels by using germinated and non-germinated wheat starch, with and without the addition of poly (ethylene oxide) (PEO). Aerogels were produced by gelatinization of starch (10% w/v, in distilled water) at 90 °C, followed by multiple freeze/thaw cycles. For the aerogel produced using starch and PEO, a solution of 6% PEO (0.6 g of PEO/10 mL of distilled water) was added to the dispersion. The thermal properties, infrared spectra, relative crystallinity, morphology, water absorption properties, and texture profile of the aerogels were evaluated. After immersion in water for 24 h, the aerogels exhibited high degradation temperature, water absorption capacity, and physical integrity. Aerogels produced using the germinated wheat starch were much more integrated structurally compared to the aerogels produced using the non-germinated wheat starch. Wheat germination did not have any impact on the textural parameters of the aerogels. However, addition of PEO increased the water absorption capacity and reduced the hardness and cohesion of the resulting aerogels. Due to the high water absorption potential, the aerogel produced in this study can serve as an absorbent matrix in food packaging.

Development of antimicrobial and antioxidant electrospun soluble potato starch nanofibers loaded with carvacrol.

In this study, a method was developed to encapsulated carvacrol in nanofibers from soluble potato starch. The carvacrol was added in starch solutions at various concentrations (0, 20, 30 and 40% v/v) and electrospun into fibers. The morphology, size distribution, thermal stability, FT-IR spectra, relative crystallinity (RC) and antioxidant of the electrospun fibers were analyzed. For mechanical properties and antimicrobial activities evaluation electrospun nonwovens were obtain. The carvacrol-loaded nanofibers showed homogeneous morphology and average diameters ranging from 73 to 95 nm. The carvacrol encapsulated in the nanofibers had greater thermal stability than the free carvacrol. FT-IR analysis showed interactions between starch and carvacrol. The RC of the nanofibers was approximately 40%. The electrospun nonwovens mechanical properties did not present significant differences (p < 0.05). The 40% carvacrol-loaded nanofibers exhibited higher antioxidant activity with 83.1% of inhibition. The electrospun nonwoven loaded with 30% carvacrol resulted in 89.0% reduction of Listeria monocytogenes, 68.0% for Salmonella Typhimurium, 62.0% for Escherichia coli and 49.0% for Staphylococcus aureus. These electrospun nonwovens sustained antimicrobial activity for at least 30 days against S. aureus. The starch nanofibers are promising materials for application as a vehicle for carvacrol release in antimicrobial and antioxidant food packages.

Electrospinning of native and anionic corn starch fibers with different amylose contents.

Through starch phosphorylation and solution aging treatments, the aim of this work was to produce electrospun fibers derived from native and anionic (modified with sodium tripolyphosphate) corn starches with amylose contents of <70% (w/w). The fibers of native and anionic corn starches (regular amylose and high amylose Hylon V/Hylon VII) were prepared by electrospinning of starch solutions dissolved in aqueous 75% formic acid (v/v) solvent. The effects of the aging (24, 48, and 72 h) on the rheology and electrical conductivity of the starch solutions, as well as the material properties (size distribution, morphology, and infrared spectrum) of the resulting electrospun fibers, were evaluated. Fibers produced from Hylon VII and Hylon V starches showed homogeneous morphologies, whereas the fibers from regular corn starches exhibited droplets and had heterogeneous morphologies, with diameter varied from 70 to 264 nm. Both native and anionic corn starches, with amylose contents of <70% (w/w), produced smooth continuous fibers. The electrospun corn starch fibers potentially can be used as carriers for the encapsulation of active components in food and packaging applications.

Immobilization of α-amylase in ultrafine polyvinyl alcohol (PVA) fibers via electrospinning and their stability on different substrates.

The objective of this study was to immobilize α-amylase in ultrafine polyvinyl alcohol (PVA) fibers by electrolysis and to evaluate its stability at different temperatures and pHs using various starch substrates such as corn starch and germinated and ungerminated wheat starches. The α-amylase-loaded ultrafine fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and loadability and enzymatic activity evaluations. Incorporation of the enzyme resulted in a slight change in fiber morphology; the fibers became flatter and thicker with increasing enzyme concentration. The mean diameters ranged from 187 to 282 nm. FT-IR spectra indicated that the enzyme was incorporated into the fibers. PVA showed a high loading capacity for α-amylase at all concentrations tested (1.0, 1.5, and 2.0% w/v), indicating that PVA is an excellent support. The enzymatic activity of α-amylase was tested on the different starch substrates; the activity was higher in the immobilized form than in the free form. Enzymatic immobilization improved the stability of α-amylase over a wide range of temperatures and pHs. Enzymatic activity was highest when germinated wheat starch was used as the substrate at different temperatures and pHs, indicating great potential for its application in hydrolysis with α-amylase.

Action of ginger essential oil (Zingiber officinale) encapsulated in proteins ultrafine fibers on the antimicrobial control in situ.

The ultrafine fibers were produced using a polymeric blend of soy protein isolate (SPI), polyethylene oxide (PEO), and zein at a ratio of 1:1:1 (v/v/v) by electrospinning. The ginger essential oil (GEO) was encapsulated in the ultrafine fibers and the morphology, Fourier-Transform Infrared Spectroscopy (FTIR) analysis, thermal properties and relative crystallinity were evaluated. The antimicrobial activity of ginger essential oil was evaluated against five bacteria (Listeria monocytogenes, Staphylococcus aureus, Escherichia coli 0157:H7, Salmonella typhimurium, and Pseudomonas aeruginosa). Based on the preliminary tests, the concentration of GEO selected to add in the polymer solution was 12% (v/v; GEO/polymer solution). The fiber produced with 12% (v/v) GEO was used for antimicrobial analysis and in situ application (in fresh Minas cheese) against L. monocytogenes by micro-atmosphere. The ultrafine fibers produced, regardless the concentration of the essential oil, presented homogeneous morphology with cylindrical shape without the presence of beads. The application of the active fibers containing 12% GEO showed high potential to be applied in food packaging to reduce microbial contamination.