Incorporation of natural antioxidants from rice straw into renewable starch films.

Abstract This study showed that rice straw waste is a valuable source for the extraction of water-soluble phenolic compounds that can be successfully incorporated into bioactive starch-based films. The major phenolic compounds in the extract were identified as ferulic, p-coumaric and protocatechuic acid using UHPLC-MS. Homogeneous films with antioxidant properties were produced by melt blending and compression molding and the changes in the physico-chemical properties were evaluated. The produced antioxidant starch films were slightly reddish-colored and exhibited good in-vitro antiradical scavenging activity against DPPH*. The addition of the antioxidant extract improved the oxygen barrier properties without negatively affecting the thermal and the water vapor barrier properties. However, antioxidant starch films turned more brittle with increasing amount of the antioxidant extract, which was probably due to interactions of phenolic compounds with the starch chains. The film forming process induced chain scission of starch molecules in all films, shown in a decrease in molecular weight of native starch from 9.1 × 106 Da to values as low as 1.0–3.5 × 106 Da. This study aids a circular economy by recycling rice straw for the production of bioactive food packaging

Effect of essential oils on properties of film forming emulsions and films based on HPMC and chitosan

[EN] Film-forming dispersions (FFD) and films, prepared by incorporating different concentrations of bergamot (BO), lemon (LO) and tea tree (TTO) essential oils into hydroxyproplymethylcellulose (HPMC) and chitosan (CH) were obtained and their physico-chemical properties were characterised. Results showed that the increment of essential oil (EO) content promoted significant changes in the size and surface charge of the FFD particles. As regards the film properties, the higher the EO content, the lower the water vapour permeability and the moisture sorption capacity. In general, the addition of EO into the HPMC or CH matrix leads to a significant decrease in gloss, transparency, tensile strength and elastic modulus of the composite films. Discriminant analyses of obtained data revealed that the polymer type was the main factor which defined the FFD and composite film behaviour. For a given polymer, although both the nature and concentration of the EO influenced FFD behaviour, the concentration played a more important role. In film properties, the discriminant analyses did not reveal different groups associated to the different nature or concentration of the essential oils, although composite films with BO appeared to differ slightly from the rest. (C) 2011 Elsevier Ltd. All rights reserved.The authors acknowledge the financial support provided by Ministerio de Educacion y Ciencia (Project AGL2007-65503). Author L. Sanchez-Gonzalez thanks Ministerio de Educacion y Ciencia (Spain) for a FPU Grant (AP2006-026)Sánchez González, L.; Chiralt, A.; González Martínez, MC.; Cháfer Nácher, MT. (2011). Effect of essential oils on properties of film forming emulsions and films based on HPMC and chitosan. Journal of Food Engineering. 105(2):246-253. https://doi.org/10.1016/j.jfoodeng.2011.02.028S246253105

Effect of hydroxypropylmethylcellulose and chitosan coatings with and without bergamot essential oil on quality and safety of cold-stored grapes

[EN] Biodegradable coatings based on hydroxypropylmethylcellulose (HPMC) or chitosan (CH) with and without bergamot essential oil were applied to table grapes, cv. Muscatel, in order to find environmentally friendly, healthy treatments with which to better preserve fresh fruit quality and safety during postharvest cold storage. Physicochemical properties (weight loss, °Brix, total phenols, antioxidant activity, colour and texture), respiration rates and microbial counts of samples were determined throughout cold storage. The coatings had a significant effect on the development of quality variables, with the additional effect of essential oil addition as a function of the polysaccharide matrix being especially notable. Although incorporation of essential oil resulted in smaller weight losses and a greater antimicrobial effect, it also led to browner samples when using CH. Chitosan coatings containing bergamot oil were more effective than pure CH and HPMC coatings at inhibiting respiration rates. All the coatings improved the mechanical resistance of the samples at the end of storage. The most recommended coating for Muscatel table grapes is CH containing bergamot oil since, despite only contributing slightly to the sample colour, this showed the highest antimicrobial activity and the greatest control of respiration rates with a reasonably good control of water loss during storage. © 2010 Elsevier B.V.The authors acknowledge the financial support provided by Ministerio de Educacion y Ciencia (Project AGL2007-65503).Sánchez González, L.; Pastor Navarro, C.; Vargas, M.; Chiralt, A.; González Martínez, MC.; Cháfer Nácher, MT. (2011). Effect of hydroxypropylmethylcellulose and chitosan coatings with and without bergamot essential oil on quality and safety of cold-stored grapes. Postharvest Biology and Technology. 60(1):57-63. https://doi.org/10.1016/j.postharvbio.2010.11.004S576360

Antioxidant starch-based films with encapsulated eugenol. Application to sunflower oil preservation

[EN] Starch films containing eugenol, which was added to the film-forming dispersion in free form or encapsulated with different wall materials (whey protein or lecithin), were obtained by casting. The physical and the antioxidant properties of the films, the release kinetics of eugenol in different food simulants and their performance at preventing sunflower oil oxidation during storage were evaluated. Encapsulated eugenol modified the film microstructure, yielding less stretchable films with reduced water affinity, transparency and oxygen permeability as compared to films formulated with non-encapsulated eugenol. The addition of eugenol microcapsules containing oleic acid promoted the eugenol retention in the starch matrix during film formation and thus, these films exhibited the greatest antioxidant activity. Films developed with encapsulated eugenol powder containing lecithin and oleic acid were highly effective at preventing sunflower oil oxidation even throughout 53 days of storage at 30¿°C, maintaining low and almost constant values of peroxide index, conjugated dienes and trienes in comparison with the control samples.The authors acknowledge the financial support provided by the Spanish Ministerio de Educacion y Ciencia (Projects AGL2013-42989-R and AGL2016-76699-R). Author Emma Talon thanks the Universitat Politecnica de Valencia for a FPI Grant (99/2011). The authors also thank the services rendered by the Electron Microscopy Service of the UPV.Talón-Argente, E.; Vargas, M.; Chiralt, A.; González Martínez, MC. (2019). Antioxidant starch-based films with encapsulated eugenol. Application to sunflower oil preservation. LWT - Food Science and Technology. 113:1-10. https://doi.org/10.1016/j.lwt.2019.108290S11011

Carvacrol encapsulation in starch or PCL based matrices by electrospinning

[EN] Carvacrol (CA) was encapsulated in polar (corn starch-Sodium caseinate, CS:NaCas) or non-polar (poly-¿-caprolactone, PCL) matrices by electrospinning (ES). Electrospunable formulations were prepared with CS:NaCas (9:1 w/w ratio), at 2, 4 and 6 wt % in water, or PCL at 5, 10 and 15 wt% in glacial acetic acid using different CA ratios (0, 5, 10 and 15 wt% with respect to the polymer). The liquid formulations were characterized for electrical conductivity, rheological behaviour and surface tension, and ES process conditions were established. The electrospun structures were analysed as to their nanostructure and CA retention. Geometry of the nanostructures obtained from the PCL systems was nanofibrillar with some beads, whereas it is particles that are mainly deposited for starch systems. PCL systems yielded better CA encapsulation efficiency (EE) than the polar ones, where greater variability was observed. The best EE (around 80%) was obtained for 15% PCL regardless of the CA ratio.The authors would like to thank the Ministerio de Economia y Competitividad of Spain, for funding this study as part of projects AGL2013-42989-R and AGL2016-76699-R and predoctoral research grant # BES-2014-068100.Tampau, A.; González Martínez, MC.; Chiralt, A. (2017). Carvacrol encapsulation in starch or PCL based matrices by electrospinning. Journal of Food Engineering. 214:245-256. https://doi.org/10.1016/j.jfoodeng.2017.07.005S24525621

Liposomal Encapsulation of Carvacrol to Obtain Active Poly (Vinyl Alcohol) Films

Lecithins of different origins and compositions were used for the liposomal encapsulation of carvacrol within the framework of the development of active films for food packaging. Liposomes were incorporated into aqueous polymeric solutions from fully (F) and partially (P) hydrolysed Poly (vinyl alcohol) (PVA) to obtain the films by casting. The particle size distribution and ζ-potential of the liposomal suspensions, as well as their stability over time, were evaluated. Liposomal stability during film formation was analysed through the carvacrol retention in the dried film and the film microstructure. Subtle variations in the size distributions of liposomes from different lecithins were observed. However, the absolute values of the ζ-potential were higher (−52, −57 mV) for soy lecithin (SL) liposomes, followed by those of soy lecithin enriched with phosphatidylcholine (SL-PC) (−43, −50 mV) and sunflower lecithin (SFL) (−33, −38 mV). No significant changes in the liposomal properties were observed during the study period. Lyotropic mesomorphism of lipid associations and carvacrol leakage occurred to differing extents during the film drying step, depending on the membrane lipid composition and surface charge. Liposomes obtained with SL-PC were the most effective at maintaining the stability of carvacrol emulsion during film formation, which led to the greatest carvacrol retention in the films, whereas SFL gave rise to the least stable system and the highest carvacrol losses. P-PVA was less sensitive to the emulsion destabilisation due to its greater bonding capacity with carvacrol. Therefore, P-PVA with carvacrol-loaded SL-PC liposomes has great potential to produce active films for food packaging applications

Improving the Scientific Literacy of Food Engineering Students in Electrohydrodynamic Processing by Means of Zein Solutions

Electrohydrodynamic processing (EHDP) has revolutionized nanotechnology since it is a simple method for developing microstructures and nanostructures from a wide range of polymer solutions using the application of high voltages. However, EHDP has scarcely been introduced into food engineering courses at any educational level, whereas it is fundamental for professionals in the discipline. The present educational article aims to introduce, for the first time, the basis of the EHDP technology and its management to students in postgraduate courses for food emulsion and related disciplines. To this end, the document reports the step-by-step preparation of zein solutions in aqueous ethanol with varying weight protein contents and the characterization of such solutions in terms of their density, viscosity, surface tension, and conductivity. Then, the methodology also describes the processability of the resultant zein solutions using EHDP. Process parameters, including applied voltage, flow-rate, and tip-to-collector distance, were studied to optimize proper deposition of zein materials in the form of a wide range of morphologies, from nanobeads to microfibers. The attained results were related to the zein solution properties and processing conditions, which can help to understand the effect of these parameters and exemplify the potential of this technology to develop novel ultrathin food hydrocolloid structures. Finally, the application of this methodology was assessed through online surveys taken during food engineering courses and findings indicate that postgraduate students appreciate the exposure provided by the experimental activities, particularly to achieve familiarity with food hydrocolloid solutions and scientific literacy in the EHDP technology

Probiotic fermented almond “milk” as an alternative to cow-milk yoghurt

Probiotics in almond-based matrices were considered as a means of obtaining fermented products which would cover both the current demand for health-promoting foods and for alternatives to standard yoghurts. Firstly, the combined effect of high pressure homogenisation (HPH) and heat treatment on the physical stability of almond “milk” was studied. The beverage was homogenised by applying 62, 103 and 172 MPa (MF1, MF2 and MF3 respectively); MF3 was also combined with two different heat treatments (85 ºC-30 min (LH) and 121 ºC-15 min (HH)). Both microstructure and colloidal stability were analysed in all the processed samples to select the most suitable treatment with which to obtain a stable product. The selected almond milk was then fermented with probiotic Lactobacillus reuteri and Streptococcus thermophilus and the final product was characterised throughout cold storage time (28 days) as to pH, acidity, serum retention and starter viability. A sensory evaluation and probiotic survival to in vitro digestion was also conducted. The results showed that the physical and structural almond-milk properties were affected by both HPH and heat treatments, obtaining the greatest stability in MF3-LH samples. The fermented milk permitted probiotic survivals above the level suggested as minimum for ensuring health benefits during the entire controlled time and, hence, can be considered as a functional food. No differences in the sensory acceptability of the product were found between 1 and 28 storage days. Therefore, a new, functional, fermented product was developed, which was suitable for targeted groups, such as the lactose-intolerant and cow-milk-protein allergic populations.</p

Vegetable milks and their fermented derivative products

The so-called vegetable milks are in the spotlight thanks to their lactose-free, animal protein-free and cholesterol-free features which fit well with the current demand for healthy food products. Nevertheless, and with the exception of soya, little information is available about these types of milks and their derivatives. The aims of this review, therefore, are to: highlight the main nutritional benefits of the nut and cereal vegetable milks available on the market, fermented or not; describe the basic processing steps involved in their manufacturing process; and analyze the major problems affecting their overall quality, together with the current feasible solutions. On the basis of the information gathered, vegetable milks and their derivatives have excellent nutritional properties which provide them a high potential and positive market expectation. Nevertheless, optimal processing conditions for each raw material or the application of new technologies have to be researched in order to improve the quality of the products. Hence, further studies need to be developed to ensure the physical stability of the products throughout their whole shelf-life. These studies would also allow for a reduction in the amount of additives (hydrocolloids and/or emulsifiers) and thus reduce the cost of the products. In the particular case of fermented products, the use of starters which are able to both improve the quality (by synthesizing enhanced flavors and providing optimal textures) and exert health benefits for consumers (i.e. probiotics) is the main challenge to be faced in future studies.</p

Application of Ultrasound Pre-Treatment for Enhancing Extraction of Bioactive Compounds from Rice Straw

The extraction of water-soluble bioactive compounds using different green methods is an eco-friendly alternative for valorizing agricultural wastes such as rice straw (RS). In this study, aqueous extracts of RS (particles &lt; 500 &micro;m) were obtained using ultrasound (US), reflux heating (HT), stirring (ST) and a combination of US and ST (USST) or HT (USHT). The extraction kinetics was well fitted to a pseudo-second order model. As regards phenolic compound yield, the US method (342 mg gallic acid (GAE). 100 g&minus;1 RS) was more effective than the ST treatment (256 mg GAE&middot;100 g&minus;1 RS), reaching an asymptotic value after 30 min of process. When combined with HT (USHT), the US pre-treatment led to the highest extraction of phenolic compounds from RS (486 mg GAE&middot;100 g&minus;1 RS) while the extract exhibited the greatest antioxidant activity. Furthermore, the USHT extract reduced the initial counts of Listeria innocua by 1.7 logarithmic cycles. Therefore, the thermal aqueous extraction of RS applying the 30 min US pre-treatment, represents a green and efficient approach to obtain bioactive extracts for food applications