Plasma modification of starch

Cold plasma enhanced natural edible materials for future food packaging: structure and property of polysaccharides and proteins-based films

Natural edible films have recently gained a lot of interests in future food packaging. Polysaccharides and proteins in edible materials are not toxic and widely available, which have been confirmed as sustainable and green materials used for packaging films due to their good film-forming abilities. However, polysaccharides and proteins are hydrophilic in nature, they exhibit some undesirable material properties. Cold plasma (CP), as an innovative and highly efficient technology, has been introduced to improve the performance of polysaccharides and proteins-based films. This review mainly presents the basic information of polysaccharides and proteins-based films, principles of CP modified biopolymer films, and the effects of CP on the structural changes including surface morphology, surface composition, and bulk modification, and properties including wettability, mechanical properties, barrier properties, and thermal properties of polysaccharides, proteins, and polysaccharide/protein composite-based films. It is concluded that the CP modified performances are mainly depending on the polysaccharides and proteins raw materials, CP generation types and treatment conditions. The existing difficulties and future trends are also discussed. Despite natural materials currently not fully substitute for traditional plastic materials, CP has exhibited an effective solution to shape the future of natural materials for food packaging.

Understanding the multi-scale structure, physicochemical properties and in vitro digestibility of citrate naked barley starch induced by non-thermal plasma

Non-thermal plasma treatment is an emerging and effective starch modification technique. In this paper, plasma pretreatment was used to modify citrate naked barley starch for enhancing the ability of citric acid to access the starch structure. Plasma treatment did not alter the granule morphology and crystalline type of starch, but degraded the starch molecules and caused more short chains. Plasma pretreatment could etch the starch surface and depolymerize the starch molecules, which increased the accessibility of citric acid for uniform hydrolysis in the subsequent esterification reaction. Therefore, plasma pretreatment significantly promoted the structural and physicochemical modification of the citrate starch, including the enhancement of the degree of substitution, the short-range ordered degree and gelatinization temperatures, and the decreases in the molecular weight, long chains of amylopectin and pasting viscosities. Meanwhile, plasma pretreatment improved the efficiency of acid hydrolysis and decreased the enzymatic digestibility, so that it showed a higher resistant starch content in comparison with its corresponding citrate starch. This paper could provide a new insight into the lower digestion rate and improved functional properties of citrate starch.

Atmospheric pressure plasma jet pretreatment to facilitate cassava starch modification with octenyl succinic anhydride

Cassava starch (CS) was pretreated with atmospheric pressure plasma jet (APPJ), followed by esterification with octenyl succinic anhydride (OSA). This study was the first report investigating the effect of APPJ on CS modification with OSA. Results showed that APPJ pretreatment could change the morphological characteristics and crystallinity of CS. Consequently, the degree of substitution and reaction efficiency significantly improved compared with the unpretreated CS (P < 0.05). In Confocal laser scanning microscopy, the fluorescence intensity of OSA-modified CS pretreated with APPJ for 10 min and 15 min was higher than those pretreated with APPJ for 1, 3, and 5 min. The onset temperature and enthalpy (ΔH) of native starch decreased after APPJ pretreatment and further decreased by OSA modification. APPJ-OSA-CS also showed better emulsion stability and emulsion activity. This study demonstrated that APPJ could be used as a novel approach to facilitate starch modification with OSA.

Application of nonthermal processing technologies in extracting and modifying polysaccharides: A critical review

Polysaccharides are natural polymer compounds widely distributed in plants, animals, and microorganisms, most of which have a broad spectrum of biological activities to promote human health. They could also be used as texture modifiers in food industry due to their excellent rheological and mechanical properties. Many researchers have shown that nonthermal processing technologies have numerous advantages, such as high extraction efficiency, short extraction time, and environmental friendliness, in the extraction of polysaccharides compared with the traditional extraction methods. Moreover, nonthermal technologies could effectively change the physicochemical properties and structural characteristics of polysaccharides to improve their biological activities or processing properties. Therefore, a comprehensive summary about the extraction and modification of polysaccharides by nonthermal technologies, including ultrasound, high hydrostatic pressure, pulsed electric fields, and cold plasma, was provided in this review. In particular, the underlying mechanisms, processing operations, and current application status of these technologies were discussed. In addition, the applications of combining nonthermal techniques with other technological methods in polysaccharide extraction and modification were briefly introduced.

Corn starch based films treated by dielectric barrier discharge plasma

Cold plasma is an innovative strategy to strengthen the polysaccharide-based films characteristics. This study evaluated the effects of dielectric barrier discharge (DBD) plasma on the hydrophilic character, water vapor permeability (WVP), and tensile properties of corn starch-based films. Starch films were exposed to plasma processing operating at an excitation frequency of 200 Hz for 10, 15, and 20 min. DBD plasma resulted in further enhanced tensile strength and stiffness, and lower hydrophilicity and water solubility; however, it did not present significant effects on the WVP of the resulting films within the ranges studied. Higher hydrophobicity, strength, and stiffness were verified after 20 min. The results presented in this work suggest that the DBD plasma has the potential to make starch-based films a more suitable packaging material.

Strategies to Increase the Biological and Biotechnological Value of Polysaccharides from Agricultural Waste for Application in Healthy Nutrition

Nowadays, there is a growing interest in the extraction and identification of new high added-value compounds from the agro-food industry that will valorize the great amount of by-products generated. Many of these bioactive compounds have shown beneficial effects for humans in terms of disease prevention, but they are also of great interest in the food industry due to their effect of extending the shelf life of foods by their well-known antioxidant and antimicrobial activity. For this reason, an additional research objective is to establish the best conditions for obtaining these compounds from complex by-product structures without altering their activity or even increasing it. This review highlights recent work on the identification and characterization of bioactive compounds from vegetable by-products, their functional activity, new methodologies for the extraction of bioactive compounds from vegetables, possibly increasing their biological activity, and the future of the global functional food and nutraceuticals market.

Dielectric barrier atmospheric cold plasma applied to the modification of Ariá (Goeppertia allouia) starch: Effect of plasma generation voltage

The goal of this paper was to evaluate the influence of a range of plasma generation voltages on the physicochemical, structural, and technological properties of Aria (Goeppertia allouia) starch. Untreated (0 kV) and high voltages of cold plasma generation (7, 10, 14, and 20 kV) treated samples were evaluated according to their amylose content, pH, groups carbonyl/carboxyl, molecular size distribution, structure and technological properties (empirical viscosity, hydration properties, thermal analysis and gel strength). The applied voltage of 14 kV resulted in the greatest depolymerization of the starch chains, while 20 kV allowed the formation of oxidized complexes, promoting crosslinking of the starches chain. The cold plasma technique did not affect the levels of resistant starches, but increased the starch digestibility. The increased carbonyl and carboxyl groups also influenced the paste viscosity, improved hydration properties. This study suggests that the cold plasma technique can be useful in the controlled modification of starches, producing starches with different technological properties.

Green Design of Novel Starch-Based Packaging Materials Sustaining Human and Environmental Health

A critical overview of current approaches to the development of starch-containing packaging, integrating the principles of green chemistry (GC), green technology (GT) and green nanotechnology (GN) with those of green packaging (GP) to produce materials important for both us and the planet is given. First, as a relationship between GP and GC, the benefits of natural bioactive compounds are analyzed and the state-of-the-art is updated in terms of the starch packaging incorporating green chemicals that normally help us to maintain health, are environmentally friendly and are obtained via GC. Newer approaches are identified, such as the incorporation of vitamins or minerals into films and coatings. Second, the relationship between GP and GT is assessed by analyzing the influence on starch films of green physical treatments such as UV, electron beam or gamma irradiation, and plasma; emerging research areas are proposed, such as the use of cold atmospheric plasma for the production of films. Thirdly, the approaches on how GN can be used successfully to improve the mechanical properties and bioactivity of packaging are summarized; current trends are identified, such as a green synthesis of bionanocomposites containing phytosynthesized metal nanoparticles. Last but not least, bioinspiration ideas for the design of the future green packaging containing starch are presented.

The improving effects of cold plasma on multi-scale structure, physicochemical and digestive properties of dry heated red adzuki bean starch

The effect of dry heat (DH, 130 °C, 1, 3 and 9 h), cold plasma (CP, 40 V, 1, 5 and 10 min) and their combination (D-P) treatment on the structure, physicochemical and digestive properties of red adzuki bean starch were studied. The results showed that DH or CP had slight change in morphology while diffraction pattern of starch was remained. With the extension of treated time of DH and CP, the amylose content, crystallinity, molecular weight, short-range order, the long chain of amylopectin, enthalpy value, swelling power, digestibility were reduced, while gelatinization temperatures, the short chain of amylopectin and solubility were increased. The D-P had deeper modification than the single treatment. The combination of dry heat and cold plasma is a simple and green method to improve the starch structure and enhance starch properties and this modified starch could be implemented to tailor starch to the desired food applications.

Investigation on the role of the free radicals and the controlled degradation of chitosan under solution plasma process based on radical scavengers

This study investigated the role of various active species (OH, O, and H₂O₂) under solution plasma process (SPP) degradation based on the influence of different radical scavengers on the degradation effect and ESR spectra. The structures of oligochitosan with different radical scavengers were characterized by FT-IR, ¹H NMR, and XRD analysis. The results indicated that OH, O, and H₂O₂ played important roles in SPP degradation. The degradation effect of the O was even higher than that of the OH. The physical effects (e.g. UV light and shockwaves) of SPP method or Fenton's reaction might contribute to the degradation treatment. Furthermore, the different scavengers could adjust the degradation effect of the corresponding free radicals. FT-IR, ¹H NMR, and XRD analysis revealed that the primary chemical structure of chitosan was not changed by the scavengers. This study found that the controlled degradation by addition of a radical scavenger is feasible. Therefore, this study provided a straightforward analysis of the role of the free radicals and the controlled degradation of chitosan under SPP treatment, which will be beneficial to further develop SPP techniques for chitosan degradation.

Applications of nonthermal plasma technology on safety and quality of dried food ingredients

Cold plasma technology is an efficient, environmental-friendly, economic and noninvasive technology; and in recent years these advantages placed this novel technology at the centre of diverse studies for food industry applications. Dried food ingredients including spices, herbs, powders and seeds are an important part of the human diet; and the growing demands of consumers for higher quality and safe food products have led to increased research into alternative decontamination methods. Numerous studies have investigated the effect of nonthermal plasma on dried food ingredients for food safety and quality purposes. This review provides critical review on potential of cold plasma for disinfection of dried food surfaces (spices, herbs and seeds), improvement of functional and rheological properties of dried ingredients (powders, proteins and starches). The review further highlights the benefits of plasma treatment for enhancement of seeds performance and germination yield which could be applied in agricultural sector in near future. Different studies applying plasma technology for control of pathogens and spoilage micro-organisms and modification of food quality and germination of dried food products followed by benefits and current challenges are presented. However, more systemic research needs to be addressed for successful adoption of this technology in food industry.

Structural modification and functional improvement of starch nanoparticles using vacuum cold plasma

Starch nanoparticles (SNPs) have become one of the most interesting nanocarriers due to their relatively easy synthesis, biocompatibility, and biodegradability. However, the practical applications of SNPs are limited, as their aggregation reduce their functionality. Here, SNPs obtained by recrystallizing debranched waxy maize starch were modified using oxygen and ammonia vacuum cold plasma (CP). The modified SNPs were measured using Fourier transform infrared spectroscopy, showing a new carbonyl or carboxyl peak at 1720 cm^-1. SNPs modified with oxygen CP treatment have negative charges (-21.6 to -15.1 mV). Modified SNPs with diameter ranging from 75.94 to 159.72 nm had good dispersibility without much aggregation. The relative crystallinity of modified SNPs decreased from 44.13% to 33.80%. Moreover, modified SNPs showed high absorption of tea polyphenols, indicating that as nanocarriers, they can accommodate more cargo molecules than primary SNPs. CP modification of SNPs is simple, green, and inexpensive. Modified SNPs can be used as nanocarriers to deliver drug or food components in the food and pharmaceuticals industries.

Quality Evaluation of Rice Treated by High Hydrostatic Pressure and Atmospheric Pressure Plasma

This study applied high hydrostatic pressure (HHP) and atmospheric pressure plasma (APP) treatments to rice and examined the effects of the treatments on the microbial contamination and physicochemical properties. The microbial population was 100% sterilized by HHP and reduced by up to 34% by APP. Color a values were increased by up to 285% and 33% in HHP and APP, respectively. HHP increased fructose (∼8,256%) but decreased glucose, sucrose, and maltose (∼97%, −100%, and −93%, respectively). APP only mildly modified sugar composition compared with HHP. Retrogradation factors were not changed remarkably by HHP or APP. In conclusion, HHP sterilized microorganisms, but the sterilization was accompanied by high modifications to color and sugar composition. APP had a lesser effect on the microbial population, but it only mildly changed the physicochemical properties of the rice. Therefore, application of either HHP or APP could be considered depending on the intended use of the rice.

Effect of an Atmospheric Pressure Plasma Jet on the Structure and Physicochemical Properties of Waxy and Normal Maize Starch

In present study, a novel physical modification of waxy maize starch (WMS) and normal maize starch (NMS) was investigated by using an atmospheric pressure plasma jet (APPJ) treatment. The effect on the structure and physicochemical properties of both starches was demonstrated by treatment with a 5% starch suspension (w/w) with APPJ for short periods of time (1, 3, 5, or 7 min). The pH of WMS and NMS was decreased after APPJ treatment from 5.42 to 4.94, and 5.09 to 4.75, respectively. The water-binding capacity (WBC) (WMS: 105.19%⁻131.27%, NMS: 83.56%⁻95.61%) and swelling volume (SV) (WMS: 2.96 g/mL⁻3.33 g/mL, NMS: 2.75 g/mL⁻3.05 g/mL) of the starches were obviously increased by APPJ treatment. The surfaces of starch granules were wrecked, due to plasma etching. No changes in the crystalline types of both starches were observed. However, the relative crystallinities (RCs) of WMS and NMS were reduced from 46.7% to 42.0%, and 40.1% to 35.7%, respectively. Moreover, the short-range molecular orders of both starches were slightly reduced. In addition, APPJ treatment resulted in lower gelatinization temperature and enthalpies. Therefore, APPJ provides a mild and green approach to starch modification, showing great potential for applications in the food and non-food industry.

Effects of Nonthermal Plasma Technology on Functional Food Components

Understanding the impact of nonthermal plasma (NTP) technology on key nutritional and functional food components is of paramount importance for the successful adoption of the technology by industry. NTP technology (NTPT) has demonstrated marked antimicrobial efficacies with good retention of important physical, chemical, sensory, and nutritional parameters for an array of food products. This paper presents the influence of NTPT on selected functional food components with a focus on low-molecular-weight bioactive compounds and vitamins. We discuss the mechanisms of bioactive compound alteration by plasma-reactive species and classify their influence on vitamins and their antioxidant capacities. The impact of NTP on specific bioactive compounds depends both on plasma properties and the food matrix. Induced changes are mainly associated with oxidative degradation and cleavage of double bonds in organic compounds. The effects reported to date are mainly time-dependent increases in the concentrations of polyphenols, vitamin C, or increases in antioxidant activity. Also, improvement in the extraction efficiency of polyphenols is observed. The review highlights future research needs regarding the complex mechanisms of interaction with plasma species. NTP is a novel technology that can both negatively and positively affect the functional components in food.