Effect of ultrasounds and high pressure homogenization on the extraction of antioxidant polyphenols from lettuce waste

The possibility to exploit ultrasound (US) and high pressure homogenization (HPH) to obtain ethanolic antioxidant extracts from lettuce waste was studied. The application of US (400\u202fW, 24\u202fkHz) for 120\u202fs led to polyphenol extraction yield (81\u202f\u3bcg/mL) and antioxidant activity (101\u202f\u3bcg\u202fTE/mL) significantly higher than those obtained by traditional solid-liquid extraction at 50\u202f\ub0C for 15\u202fmin. Despite the intense cell rupture effect, the application of HPH pre-treatments resulted in 25% lower phenolic yields as compared to US solely, possibly due to the 40% activation of polyphenoloxidase (PPO) upon HPH treatment. Industrial relevance The waste generated by fresh-cut processing of lettuce poses environmental and economic issues to companies, leading to the need for alternative strategies for its management. US can be successfully exploited as time-saving extraction procedure for obtaining antioxidant extracts from lettuce waste

Structure of oleogels from \u3ba-carrageenan templates as affected by supercritical-CO2-drying, freeze-drying and lettuce-filler addition

Templates intended for food-grade oleogel production were produced by supercritical-CO2-drying and freezedrying of \u3ba-carrageenan hydrogels (0.4 g/100 g). Supercritical-CO2-drying produced hard (61 N firmness) and shrunk oleogels, which presented 80% oil content and no oil release. Freeze-drying allowed obtaining soft (2 N) oleogels, with 97% oil content but presenting a high oil release (49%). Lettuce homogenate, used as water phase of the hydrogel, acted as inactive filler agent of template network. It allowed reducing shrinkage and firmness (10 N) of supercritical-CO2-dried oleogels, which presented 94% oil content and 5% oil release. In the case of freeze-dried templates, lettuce-filler increased firmness (4 N) but reduced oil release (34%). SEM image analysis highlighted that the physical properties of \u3ba-carrageenan oleogels can be explained based on the effect of drying technique and lettuce-filler addition on the porous microstructure of the dried templates

Innovative bioaerogel-like materials from fresh-cut salad waste via supercritical-CO2-drying

Fresh-cut salad waste was dried by means of supercritical carbon dioxide technology using ethanol as co-solvent. The obtained material was characterized by a white color and a brittle texture. Microscopic images revealed an aerated structure, with well-evident intra and inter-cellular spaces. Based on the high internal surface (> 100m2/g), the extremely low density ( 80%), supercritical-dried salad waste can be regarded as a bioaerogel-like material. One gram of this material absorbed 33 and 19 g of water and oil respectively. Industrial application: Fresh-cut processing of salad generates large amounts of solid waste which is not suitable for conversion into biogas or fertilizers. This waste poses management issues for producers and represents an environmental burden. Fresh-cut salad waste could be valorized to produce bioaerogel-like materials with enhanced solvent uptake ability, to be exploited as food ingredients, packaging, absorbents or innovative carriers for both lipophilic and hydrophilic compounds

Controlling aerogel surface porosity to enhance functionality in foods

Aerogels based on biopolymers, such as proteins, are food-grade materials characterized by distinctive physical properties, which make them intriguing candidates for the development of new ingredients with unique functionalities. The aerogel typical aerated structure can be exploited to deliver health-protecting bioactives or reduce food calories by increasing air content. However, aerogel porosity is easily lost upon contact with liquid food ingredients (water and oil). This issue might be overcome by closing the pores at the aerogel surface. In this work, processing and formulation strategies were applied to increase the structural stability of whey protein aerogels obtained by traditional ethanol exchange and supercritical-CO2-drying. Aerogels characterized by different levels of surface collapse were obtained by subjecting alcolgels to a controlled ethanol evaporation procedure prior to supercritical-CO2-drying. Alternatively, aerogels were coated with hydrophilic (alginate, agar) or hydrophobic (ethylcellulose) polymers. Aerogel microstructure was studied by SEM. Water and oil absorption kinetics were then measured. Ethanol evaporation time, polymer concentration and gelation rate were identified as key parameters affecting aerogel surface structure, allowing to significantly decrease water and oil absorption kinetics in the aerogels. This study suggests that aerogel structure-driven functionalities could be maintained in complex food formulations by controlling aerogel surface porosity

Effect of expiry date communication on acceptability and waste of fresh-cut lettuce during storage at different temperatures

The effect of expiry date communication on acceptability and wasting risk of fresh-cut lettuce was investigated. Fresh-cut lettuce was packed in plastic pouches reporting or not the expiry date on the label and stored at recommended (8 \ub0C) or abuse temperature (12 \ub0C) for increasing time up to 21 days. Lettuce was assessed during storage for colour, total viable count, consumer rejection and wasting risk. Independently on storage temperature, the presence of the expiry date caused an increase of wasting risk. When lettuce was stored at 8 \ub0C, about 4% packages were estimated to be wasted within the expiry date (7 days). Even a lower amount of waste was estimated when expiry date was not reported. Within 7 days of storage at 12 \ub0C, 12% of the packages without expiry date was estimated to be wasted. This percentage increased to 27% when the expiry date was printed on the lettuce label. Results emphasise the dramatic effect of the presence of the expiry date on the consumer decision to waste food

Protein aerogels as functional ingredients able to replace fat and modulate lipid digestion

Introduction The direct relation between saturated fat consumption and chronic diseases such as cardiovascular diseases, diabetes type II and obesity is nowadays well-established. However, fat substitution in foods is not simple, due to the important structural and sensorial properties of solid fat, which are hardly replicated by liquid oil. Nevertheless, oil can be structured into semi-solid materials (oleogels) by different “oleogelation” strategies. Oleogels not only mimic the structural properties of fats, but have been also shown to be useful in the modulation of lipid digestion. The aerogel-template approach, is a recent oleogelation strategy, based on the ability of aerogels to absorb oil in their porous network. In particular, food-grade protein aerogel particles have shown the peculiar ability to structure huge oil amounts into plastic systems presenting the mechanical properties of traditional fats. The aim of the present study was to assess the effect of aerogel-template oleogelation on lipid digestibility and to investigate the possibility to use aerogel-templated oleogels in the preparation of low-saturated fat cocoa creams. Experimental Methods Whey protein (WP) aerogel particles were prepared by grinding a heat-set WP hydrogel (20% w/w, pH=5.7), which was then subjected to ethanol exchange and supercritical-CO2 drying (SCD). Oleogels were than obtained by absorption of sunflower oil (SO) into aerogel particles. Lipid digestibility of the oleogel containing 80% (w/w) SO and 20% WP aerogel (w/w) was assessed by in vitro digestion, according to the INFOGEST protocol. Lipid digestibility was expressed as free fatty acids (FFA %), assessed by pH-stat method, i.e., by measuring the volume of NaOH (0.25 M) required to maintain the pH at 8.00 during digestion occurring in the small intestine. The choice of using pH 8.00 instead of 7.00 was based on the technical specifications of the used lipase. The digestate samples were analyzed by using dynamic light scattering (DLS) and confocal microscopy. The WP aerogel particles were then used to prepare cocoa creams containing sunflower oil (SO), icing sugar and cocoa powder. Different oil amounts were tested (40-65% w/w), while maintaining constant the ratio among the dried ingredients (WP aerogel:sugar:cocoa =1.5:5:1). Additional control samples were prepared by using native WP. The obtained creams were analyzed for oil release and rheological properties and compared to cocoa spreads available on the market. Results and discussion WP aerogel particles were used to structure SO into an oleogel, whose digestibility was then assessed. The lipid digestibility of SO and of the oleogel resulted respectively of 70% and 80%. These results can be attributed to the ability of aerogel protein particles to improve the emulsification of oil in the intestinal digestive mixture, leading to an enhanced activity of lipolytic enzymes. DLS, in fact, evidenced that the lipidic micelles formed during intestinal digestion of the oleogel resulted significantly smaller than those formed during SO digestion. This is probably attributable to the surface activity of WP aerogels, which are able to cover and stabilize the oil droplets in the digestive mixture. The applicability of WP aerogel particles as key ingredients for the preparation of low-saturated fat cocoa creams was then demonstrated, combining WP aerogel particles with SO in presence of sugar and cocoa powder. Native WP did not show oil structuring ability, leading to liquid-like cocoa creams, showing an apparent viscosity lower than 2 Pa∙s (50 1/s) and evident oil release upon resting at room temperature. By contrast, aerogel particles produced thicker creams, showing no flow under gravity, a significantly higher viscosity (50 Pa∙s), and no oil release under standard storage conditions. This was attributed to the modifications undergone by WP during conversion into porous aerogel particles. The range of rheological properties covered by the WP aerogel cocoa creams resulted comparable with a wide variety of commercial products (e.g. sauces and batters). Conclusions This work demonstrates the potentialities of WP aerogel particles as oil structuring agents, exploitable in the formulation of healthier food products with a reduced amount of saturated fatty acids. Such formulation strategy would not compromise the lipolytic action during digestion, making aerogels suitable carriers of bioactive molecules in the gastrointestinal tract

Technological and consumer strategies to tackle food wasting

Around one-third of the globally produced food is annually discarded worldwide. This amount would be able to satisfy ten times the need of undernourished people. If nothing is done, the mass of discarded food could further rise, compromising the right to food of future generations. Almost all food discards are nowadays disposed of or used for energy recovery. Strategies for recovery of value-added compounds have also been proposed. However, more sustainable options are available. In this context, food science skills are required to develop novel approaches that could allow both reducing disposal of discards and preventing their generation. Effective technological strategies are expected to directly reduce food loss within the production chain but also to drive consumer towards more sustainable choices and behaviours. This review paper summarizes recent developments in possible technological and consumer strategies to tackle food wasting. To this aim, after defining, classifying and quantifying food discards, reasons and responsibilities of discard generation are analysed in the light of the current regulatory efforts. Based on this survey, an overview of possible interventions is provided, underlying their synergistic effects on waste reduction/prevention at industrial and domestic levels

Potentialities of plant protein aerogels as innovative food ingredients

Protein aerogels are attracting large attention in the food sector, since presenting appealing characteristics as innovative food ingredients. Being made by proteins, commonly used food ingredients, they are largely accepted by consumers. Moreover, the structure of protein aerogels can be fine-tuned by acting on multiple processing (e.g., drying technique) and formulation (e.g., protein type, pH) factors, thus allowing the engineering of systems with a wide range of tailor-made functionalities. As a result, protein aerogels have been proposed as advanced food ingredients to develop bioactive delivery systems in the gastrointestinal tract, and structure liquid oil into plastic materials able to replace saturated fats in foods. Surprisingly, to date, the potentialities of protein aerogels as innovative food ingredients have been only demonstrated for animal protein-based systems, mainly egg and milk proteins, and studies regarding the development of aerogels from plant proteins are very limited. Nevertheless, the current concern about the poor environmental sustainability of animal proteins and their production is boosting the so-defined “plant-protein transition”, which has been identified as a key strategy to increase of food sustainability. In this context, plant-protein-based aerogels could represent an influential opportunity to favor the inlet of aerogels in the food sector. Based on these considerations, the aim of the present work was to study the possibility of producing food-grade aerogels based on plant proteins (pea and soy) and to collect preliminary data on their compatibility with food systems. To this aim, soy and pea protein isolate (SPI, PPI) hydrogels (10-20% w/w, pH 4.5 or 7.0) were converted into aerogel particles by grinding followed by ethanol solvent exchange and supercritical-CO2-drying. The obtained aerogel particles were analyzed for physical properties (BET surface area, porosity, density), and ability to interact with water and oil, commonly used food solvents. To this aim, aerogel water solubility and water and oil holding capacity (WHC, OHC) were assessed and compared to those of SPI and PPI. Aerogelation of SPI and PPI allowed obtaining porous particles, with BET internal surface and porosity in the range 50-150 m2/g and 60-80% respectively. The lowest values were found, as expected, at pH 4.5, corresponding to the isoelectric point. As compared to SPI and PPI, which presented a water solubility higher than 80%, the corresponding aerogels showed a water solubility around 25%. Aerogelation also significantly increased the WHC and OHC as compared to the protein isolates. The results obtained in this study demonstrate the possibility to produce plant-protein-based aerogels in the form of porous powders. The high ability to absorb water and oil, which can be exploited in the formulation of complex foods requiring rheological modulation (e.g., creams, spreads, dressings), associated with the vegetable origin of the used proteins, can be regarded as key characteristics able to stimulate the interest of the food sector in innovative aerogel ingredients

Shelf-life Assessment of Food Undergoing Oxidation\u2013A Review

Oxidation is the most common event leading to the end of shelf life of microbiologically stable foods. Thus, a reliable shelf-life assessment is crucial to verify how long the product will last before it becomes oxidized to an unacceptable level to the consumers. Shelf-life assessment strategies of foods and beverages suffering oxidation are critically discussed focusing on definition of the acceptability limit, as well as the choice of the proper oxidative indicators, and methodologies for shelf-life testing. Testing methodologies for shelf-life determination under actual and accelerated storage conditions are considered, highlighting possible uncertainties, pitfalls, and future research needs. \ua9 2016, Copyright \ua9 Taylor & Francis Group, LLC