Bio-based multilayer films: A review of the principal methods of production and challenges.

The development of biodegradable packaging materials has been drawing attention worldwide to minimize the environmental impact of traditional petroleum-based plastics. Nevertheless, it is challenging to obtain bio-based materials with suitable properties for packaging applications. Films produced from a single biopolymer often lack some important properties. An alternative to overcome this limitation is the multilayer assembly. Under this technology, two or more materials with specific and complementary properties are combined into a single-layered structure, thus improving the performance of bio-polymer plastics. This review presents the main aspects of bio-based multilayer film production technologies, discussing their advantages and disadvantages, which have to be considered to produce the most suitable film for each specific application. Most of the studies reported that such films resulted in increased mechanical performance and decreased water, oxygen, and dioxide carbon permeability. This approach allows the addition of compounds leading to antioxidant or antibacterial activity. Finally, a discussion about the future challenges is also presented.

Combining ethanol pre-treatment and ultrasound-assisted drying to enhance apple chips by fortification with black carrot anthocyanin.

BACKGROUND: An interesting approach to improve dried foods nutritional properties, functionality, and sensorial attributes, is by taking advantage of pre-treatments for incorporating components into the food matrix. Based on this, this work studied the incorporation of black carrot anthocyanins in apple tissue by using ethanol (concentrations 0-300 mL L-1 ) as a pre-treatment to ultrasound-assisted convective drying. Samples were pre-treated in acidified ethanol solutions, with and without anthocyanins, and then dried (50 °C, 1 m s-1 ) by convective and ultrasound-assisted convective (21.77 kHz, 20.5 kW m-3 ) drying. Both the drying process improvement and the obtained product properties were studied. RESULTS: The anthocyanins did not influence the drying kinetics. In contrast, time reduction was > 50% by using both ethanol pre-treatments and ultrasound. Ethanol pre-treatments decreased the external resistance to mass transfer, while ultrasound decreased both internal and external resistances. The impregnation increased the anthocyanins (above 947%), which were retained after drying. Colour modifications after pre-treatments and after drying (L*, b*, h° decrease, and a* increase), and antioxidant capacity retention were observed in samples with anthocyanin addition. CONCLUSION: The results point that ethanol pre-treatments and ultrasound application can accelerate drying, and through the natural colouring incorporation during pre-treatments, the nutritional properties of dried samples were better retained. © 2020 Society of Chemical Industry.

Ozonation of agri-food products for reducing mycotoxin contamination: challenges in grains and particulates processing.

This study evaluated differences in the efficiency of ozonation process to reduce the natural contamination of two mycotoxins, deoxynivalenol (DON) and zearalenone (ZEN), in wheat grains and particulate products. Three different products were used, each one representing a different structure and mycotoxin distribution: (1) wheat grains, with natural mycotoxin distribution inside and among the grains; (2) homemade pellets, with homogenous mycotoxin distribution; (3) ground homemade pellets, with homogeneous mycotoxin distribution, and smaller particles. The ozonation of naturally contaminated wheat grains did not reduce the concentrations of DON and ZEN. When the variability of contamination among replicates was reduced by the production of homemade pellets showed, the ozonation provides a reduction of 14% of ZEN concentration. Reducing the size of particles by grinding the homemade pellets, a reduction of DON (11%) and ZEN (31%) was observed, which was evidenced by the higher ozone consumption during the process. Therefore, some limitations of ozonation of grains and particulate products, such as particle dimensions and distribution of natural contamination of mycotoxins affect the degradation of DON and ZEN under real conditions. Because of this, further studies to evaluate the effectiveness of ozonation should also be performed in samples naturally contaminated to produce robustness results.

Ozone technology to reduce zearalenone contamination in whole maize flour: degradation kinetics and impact on quality.

BACKGROUND: Maize is one of the most important cereals. It is used for different purposes and in different industries worldwide. This cereal is prone to contamination with mycotoxins, such as zearalenone (ZEN), which is produced mainly by Fusarium graminearum, F. culmorum and F. equiseti. Toxin production under highly moist conditions (aw > 0.95) is exacerbated if there are alternations between low temperatures (12-14 °C) and high temperatures (25-28 °C). Even if good production practices are adopted, mycotoxins can be found in several stages of the production chain. For this reason, an alternative to reducing this contamination is ozonation. This study evaluated the reduction of ZEN in naturally contaminated whole maize flour (WMF) treated with 51.5 mg L-1 of ozone for up to 60 min. Pasting properties, peroxide value, and fatty acid composition were also evaluated. RESULTS: Zearalenone degradation in ozonated WMF was described by a fractional first-order kinetic, with a maximum reduction of 62.3% and kinetic parameter of 0.201 min-1 in the conditions that were evaluated. The ozonation process in WMF showed a decrease in the apparent viscosity, a decrease in the proportion of linoleic, oleic, and α-linolenic fatty acids, an increase in the proportion of palmitic acid, and an increase in the peroxide value. CONCLUSION: Ozonation was effective in reducing ZEN contamination in WMF. However, it also modified the pasting properties, fatty acid profile, and peroxide value, affecting functional and technological aspects of WMF. © 2019 Society of Chemical Industry.

The Hydration of Grains: A Critical Review from Description of Phenomena to Process Improvements.

Hydration is a crucial step during grain processing. It is performed prior to many other processes, such as germination, cooking, extraction, malting and fermentation. The number of publications on this topic studying the description of the mechanisms involved and recent technologies for processing enhancement has increased recently. However, due to the complexity of the hydration process, there are still many aspects that are little understood. For that reason, this review provides not only an overview of recent developments in this field, but also a critical discussion of publications from the last 2 decades, as well as suggestions for future innovative studies. This review discusses the importance of hydration in the grain industries, the pathway for water entry into the various grains, the mass transfer and fluid flow mechanisms in the process, the behavior of the hydration kinetics, the mathematical modelling, the technologies used to accelerate the process and other necessary requirements that must be performed to complement and complete our knowledge of this process.

Effect of ohmic heating on the structure and properties of flexible multilayer packaging.

Food-packaging-processing interactions define packaging materials' performance properties and product quality. This study evaluated the effect of ohmic heating (OH) processing and different food simulants on the properties of four multilayer flexible packaging materials (PETmet/PE, PETmet/PP, PET/Al/PE, and PET/Al/PA/PP). OH treatment was applied to the sealed packages containing the food simulants using a voltage gradient of 3.7 V/cm at a frequency of 20 kHz, resulting in a thermal process of at 80 °C for 1 min. The structure and performance of the different packages were then evaluated. The materials did not show changes in chemical groups nor thermal properties. However, the simulant-packaging-processing interaction resulted in changes in crystallinity, morphology, mechanical and barrier properties (water and oxygen), especially for metallized films in contact with acidic food simulants. The results indicate that although OH resulted in changes in packaging materials, these materials can be used under the conditions applied in this study.

Food-Package-Processing relationships in emerging technologies: Ultrasound effects on polyamide multilayer packaging in contact with different food simulants.

In this study, the effect of ultrasound processing on the properties of two packages widely used in food products was evaluated: polyamide (PA) and polyethylene (PE) multilayer packaging. Packages composed of PE/PA/PE (Film A) and PE/PA/PE/PA/PE (Film B) were filled with aqueous and fatty food simulants and treated in an ultrasound water bath (frequency 25 kHz, volumetric power of 9.74 W/L, temperature of 25 °C, and time of 30 and 60 min). Materials were evaluated in term of structure and performance properties. Ultrasound did not or induced small changes in chemical groups, crystallinity, melting temperature, and tensile strength of the films. Film A showed a reduction in heat sealing tensile strength of 25% in the machine direction and 22% in the transverse direction. Film B showed a 20% increase of water vapor transmission rate after ultrasound processing. Although ultrasound had little impact on the properties of the evaluated materials, these modifications do not compromise the use of these packages for applications in ultrasound-processed foods. Therefore, the results indicate that ultrasound can be used as a food processing technology in multilayer PA and PE packaging.

Use of physical processes to maximize goat milk cream hydrolysis: Impact on structure and enzymatic hydrolysis.

This study evaluated the use of ultrasound (US), high-shear dispersion (HSD), stirring (ST), and low or high pressure homogenization (LPH or HPH) technologies to modify the goat milk cream (GMC) structure, focusing on improving the enzymatic hydrolysis of its lipids. The GMC structure was evaluated, as well as its creaming and emulsion stability index (ESI). The processed GMC was hydrolyzed by lipase at 50 °C for 300 min, and the fatty acids concentration (FAC) was evaluated over the reaction. ST, HPH, and HSD showed âˆ¼ 90% lower emulsion destabilization, 10 times higher ESI, and smaller fat globule size than unprocessed GMC. The pretreatments increased the hydrolysis rate up to 2.4 times and the final FAC up to 8.7 times. ST (4 min), HPH (40 MPa) and HSD (5 min/ 25,000 rpm) showed the best results, which were correlated with the changes in the GMC structure. The results suggest that the physical treatments impacted the substrate structure, favoring enzyme activity and accelerating the hydrolysis degree. Therefore, the application of physical processes can be an interesting strategy to enhance the hydrolysis of GMC, aiming to produce compounds of industrial interest.

Evaluation of ozone technology as an alternative for degradation of free gossypol in cottonseed meal: a prospective study.

Free gossypol is a toxic compound which naturally occurs in cottonseed and its derivates, affecting animal and possibly human health. Consequently, alternatives for gossypol destruction must be evaluated. This work evaluated the emerging technology of ozone processing for free gossypol destruction in cottonseed meal. Ozonation was carried out in the actual cottonseed meal and also a model system, designed to describe the involved mode of action. The model system consisted of glass pearls beads covered with free gossypol. Ozonation was performed in two ways: as a static process, i.e., without homogenising the sample after placing them in the reactor, and also homogenising it. Ozone degraded free gossypol in all the systems, but reaching different levels. Free gossypol reduction was higher in the model system than the cottonseed meal, and higher in the homogenised processing than the static one: cottonseed meal in homogenised (56%) and static (25%); model system homogenised (98%) and static (80%). The obtained differences suggest a problem of gas penetration in the solid particles, the effect of unexposed surfaces due to contact areas, and the reaction with other organic molecules further than the target. Ozonation is a promising technique for gossypol degradation in cottonseed meal, but additional strategies are needed to optimise the ozonation process and evaluate toxicological aspects.

Enhancing carrot convective drying by combining ethanol and ultrasound as pre-treatments: Effect on product structure, quality, energy consumption, drying and rehydration kinetics.

Ultrasound was combined with ethanol to improve different aspects of carrot convective drying, evaluating both processing and product quality. The ultrasound in water treatment resulted in cellular swelling and small impact on texture. Differently, the ultrasound in ethanol and ethanol treatments modified both carrot microstructure (cell wall modifications of parenchymatic tissue) and macrostructure (shrinkage and resistance to perforation). Pre-treatments with ultrasound in ethanol and ethanol improved the drying kinetics, reducing the processing time (~50%) and the energy consumption (42-62%). These pre-treatments also enhanced rehydration, whose initial rate and water retention were higher than the control. In addition, the carotenoid content was preserved after drying, for all the treatments. Any impact on shrinkage was observed. A mechanistic discussion, based on structural modification (microstructure and macrostructure) and physical properties of water and ethanol, was provided. As conclusion, this work not only described positive aspects of combining the technologies of ultrasound and ethanol as pre-treatments to convective drying, but also proposed mechanisms to explain the phenomena.

Dual-process of starch modification: Combining ozone and dry heating treatments to modify cassava starch structure and functionality.

This work evaluated for the first time the effect of dual modification of cassava starch by using ozone (O3) and dry heating treatment (DHT). The dual modification was capable to promote fissures on the surface of the starch granule (DHT + O3), affected the starch amorphous domains, presented greater degree of starch oxidation (DHT + O3) and different profiles of starch molecular size distribution. These modifications resulted in starches with different properties. Moreover, the sequence of treatments was decisive for the hydrogel properties: while DHT + O3 resulted in formation of stronger gels, O3 + DHT resulted in weaker gels. In conclusion, this proposed dual modification was capable to produce specific modified starch when compared with the isolated treatments, also expanding the potential of cassava starch applications.

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.

Structural changes caused by ultrasound pretreatment: Direct and indirect demonstration in potato cylinders.

This work aimed to demonstrate the internal and external structural changes in potato cylinders caused by different times of ultrasound pretreatment. In addition, the structural changes were associated with the viscoelasticity and mass transfer. For which, potato cylinders were immersed in distilled water and pretreated with and without ultrasound (ultrasonic bath of 91 W/L and 25 kHz) up to 120 min. Then, the microstructure was evaluated by stereoscopic observation as a direct method, and by viscoelasticity and mass transfer evaluation (pigment diffusion and drying) as indirect methods. Both external and internal structure of the material were evaluated. As results, it was demonstrated the formation of microchannels inside the potato tissue as well as the surface erosion caused by ultrasound, especially after 60 min of pretreatment. Further, it was observed that the product viscoelasticity is affected by the ultrasound pretreatment reducing the elasticity. In addition, the mass transfer on the cylinders was improved by ultrasound pretreatment. The pigment transfer was enhanced, demonstrating the acoustic erosion at the sample border. Furthermore, the drying process was accelerated by ultrasound, demonstrating the reduction of the internal resistance to water transfer. Finally, it was observed that high structural changes on the potato cylinders can bring some disadvantages such as changes on the color and severe shrinkage. This work concluded that the structural changes caused by ultrasound can be evidenced directly and indirectly. Furthermore, different structural changes took place, on both inside and outside of the vegetable sample. However, despite ultrasound improves further process, especially those that involve mass transfer, the parameters time and ultrasonic power must be optimized to obtain desirable results without reducing the product quality.

Combining Ionizing Irradiation and Ultrasound Technologies: Effect on Beans Hydration and Germination.

The present work studied, for the first time, the effect of two technologies on the hydration and germination process of beans: ionizing irradiation and ultrasound. In addition, this work proposed a possible biological effect of ultrasound to describe its effect on grain hydration. Carioca beans were irradiated at doses of 2.3 and 3.8 kGy using γ-rays, establishing different metabolic activities for the beans. Then, they were hydrated with and without the ultrasound technology (91 W/L and 25 kHz) at 25 °C. Both the hydration and germination kinetics were evaluated considering the application of both technologies alone and in combination. As results, irradiation did not significantly affect (P > 0.05) the hydration rate, the equilibrium moisture, or the lag phase time, but ultrasound affected them, reducing 50% of the processing time. On the other hand, only the equilibrium moisture was slightly reduced by the interactive effect of irradiation and ultrasound technology, which was discussed based on different metabolism levels. Furthermore, the germination process of carioca bean was hindered by both the studied variables, reducing its germination capacity to 0% in some cases. Therefore, by studying the effect of ultrasound on beans with different active metabolism (due to different irradiation doses), it was suggested that both physical and biological mechanisms are involved during hydration process and that both can be affected by ultrasound. Further, irradiation could be used on carioca beans with objectives such as avoid germination, insects, and microorganism's growth, without an important effect on the hydration kinetics. PRACTICAL APPLICATION: Ultrasound technology has demonstrated to accelerate the soaking process of several legume grains. However, sometimes, grains are irradiated for disinfestation purpose to improve their shelf life. Indeed, irradiation can change the grain properties as the cooking time, hydration time, and germination capacity. Therefore, this work verified if irradiation changes the desirable effect of ultrasound on grain processing: soaking and germination. Moreover, this work novelty is also based on describing the phenomena: by proposing a possible biological effect, further approaches to improve the grain processing can be achieved.

Properties and possible applications of ozone-modified potato starch.

In this work, different properties of potato starch modified by ozone oxidation were evaluated and described aiming to represent different possibilities of industrial application. The most promising results were observed regarding the pasting properties and the gel texture of the starch samples ozonated for 15 and 30 min. These samples presented a higher apparent viscosity and a higher gel strength when gelatinized at 65 and 70 °C, if compared to the native sample. Furthermore, the 15 and 30-min samples retained more water at mild temperatures (~60 °C) than the other samples. These results could be related to the less compact structure of the oxidized starches after the ozone processing due to the cleavage of their glycosidic bonds and the presence of electronegative groups. Not only do these characteristics facilitate the water absorption and gelatinization of the samples at mild temperatures, they also favour the granular disruption at higher temperatures (above 85 °C). The data reported in this work broadens the understanding of the ozone-modification process, as well as suggesting possibilities of industrial applications using ozonated potato starch.

Irradiation of mung beans (Vigna radiata): A prospective study correlating the properties of starch and grains.

In this work, the effect of Gamma-irradiation was evaluated on the characteristics of mung bean (Vigna radiata) grains and starches, considering doses up to 5 kGy. For this purpose, the starch structure and properties were evaluated, as well as the grains' hydration, germination and cooking. The irradiation process was able to change the characteristics of both mung bean starches and grains. The starch structure was partially changed, presenting smaller molecules and small changes in the granule morphology. No alterations were observed in the starch X-ray diffraction pattern, while lower pH was achieved. Considering the starch properties, it was observed lower water retention ability at 75 °C, lower apparent viscosity, higher paste clarity and, in general, harder and less viscous gels. The ionizing radiation accelerated the hydration, reduced the germination capacity and improved cooking time of the mung bean grains. The results proved the efficacy of using ionizing radiation, at the doses applied in this work, to desirably modify the mung bean starch and grains.

Ozone technology as an alternative to fermentative processes to improve the oven-expansion properties of cassava starch.

Cassava starch has a remarkable importance in the food industry and it can be used either as ingredient or additive. The sour cassava starch is a product with a good oven-expansion capacity and several applications, being especially important as an alternative for gluten-based products. However, it is obtained through natural fermentation followed by solar drying, which hinders its production and application. In this context, this work proposed the ozone processing as an alternative to obtain cassava starch with good oven-expansion property. The effect of ozonation on starch granular and molecular structure was evaluated, as well as on the main starch properties. The ozone processing reduced the starch molecular size, also forming carbonyl and carboxyl groups. The structural changes led to pastes with higher clarity, better oven expansion and softer texture. The improvement in starch properties and technological aspects were related with the molecular changes. In conclusion, ozone oxidation was proved to be a viable and easier alternative for the conventional process.

Combining ozone and ultrasound technologies to modify maize starch.

In this work, maize starch was modified using ultrasound (US) and ozone (O3) treatments, each one alone and also in combination. The starch molecular structure, granule characteristics and properties were evaluated. The US treatment alone did not show influence on the starch physical characteristics. On the other hand, the O3 treatment, alone or in combination with US, led to significant changes on starch molecules by increasing carbonyl and carboxyl groups and the apparent amylose content, while decreasing pH and the starch molecular size distribution. The granules' particle size distribution (PSD), their morphology and crystallinity were not affected by any of the treatments. Regarding the starch properties, water absorption index (WAI), water solubility index (WSI), pasting properties and gel strength were clearly more affected by the ozone treatment as compared with the ultrasound treatment. However, the paste clarity was significant higher when the combined treatments were applied, especially when US was used before O3. These results are prompting the hypothesis that the US treatment improved the subsequent action of O3.

Ozonation of cassava starch to produce biodegradable films.

In this study, biodegradable films were produced from cassava starch modified by ozone at different levels. The films were produced by casting technique using native and ozonated cassava starch, glycerol as the plasticizer, and water as the solvent. Films were characterized in term of their mechanical, barrier and functional properties, morphology, crystallinity, colour, and opacity. The morphology of the ozonated films was more homogeneous in comparison to the films produced with the non-modified starch and enhanced properties were achieved. Films produced with ozonated cassava starch presented higher tensile strength, Young's modulus and lower elongation. The water vapour permeation and the oxygen permeation were increased by increasing the ozonation time. Moreover, ozone processing resulted in films with a more hydrophilic surface and lower solubility after 24 h. Possible explanations and applications were discussed. In conclusion, the ozone processing showed to be a good alternative for starch based packaging production.

The ultrasound assisted hydration as an opportunity to incorporate nutrients into grains.

Hydration is an important but long step in processing beans. Consequently, any ways of taking advantage of this processing time are desirable. One possibility is to fortify the beans during the hydration process, especially with water-soluble nutrients. This work studied the incorporation of iron into beans during hydration with and without ultrasound, describing the kinetics of water and iron uptake, the entrance pathway and its effect on germination and the cooking process. For that, carioca beans were soaked in ferrous sulfate solution (0.271% w/v) with and without ultrasound (91 W/L; 25 kHz) at 25 °C. It was demonstrated that iron could be incorporated during the hydration process, describing a similar kinetics behavior to the water uptake. In addition, ultrasound accelerated this process, achieving 60.1 mg Fe/100 g w.b. after 510 min of process, in contrast to 34.4 mg Fe/100 g w.b. when the beans were hydrated without ultrasound. Finally, by hydrating the beans with ferrous sulfate, the cooking process was accelerated, which is desirable. However, the capacity for germination of the beans was reduced. In conclusion, the hydration process time can be used to fortify the beans with iron (and, possibly, other water-soluble nutrients). Nevertheless, future studies must be performed to determine if the incorporated iron is bioavailable and bioaccessible, as well as how relevant this approach is as a nutritional policy.