Toxicological analysis of metals content in agro-food wastes as possible supplement in animal feed.

The agro-food surplus is considered the most abundant renewable resource, interesting for the economic and environmental impact, with a possible employment in different productive fields such as supplement in animal feed. For a safe and effective enhancement of agro-food wastes it is needed a toxicological analysis before of their employment, to avoid potential risks to animals, humans and environment. The purpose of this study was to evaluate the metals content (Cu, Fe, Zn, Mg, Na, K, Ca, Mn, Se, Zn, Co, Ni, V, Sb, Mo, Cr and Pb, Cd, As, Ba), in agro-food wastes through ICP-MS analysis. The results obtained showed the presence of metals analysed with a significant content of essential micro and macro-elements; with regard to toxic metals, only strawberries and fennel samples showed Pb levels above the MRL. These data confirm, from the toxicological point of view, a possible and safe reuse of the most of all agro-food wastes, as raw material at low cost and rich of essential nutrients and particularly as supplement in animal feed.

Valorization of agro-food wastes: Ease of concomitant-enzymes production with application in food and biofuel industries.

The novel and greener approach toward the co-production of hydrolytic enzymes in a single-cultivation medium with inexpensive substrates can bring down the production costs. Likewise, the natural and industrial organic biomass/solid are all nutritionally rich substrates waiting for free use in industries such as food, biofuel, etc. Valorization must broaden its applications in industries and households with a step towards a sustainable environment. The biofuel approach can be projected as one of the most promising deputations to meet future energy demands, in reduction of the environmental pollution due to excessive fossil fuel consumption. The present review highlights the multifaceted stature of microbial enzymes in this direction and possible implications mainly in the food industry and biofuel with the global impact of similar bio-based industries. In this review, design scale-up, fermentation cost, energy needs,and agro-food waste management have been meticulously delineated.

Yarrowia lipolytica as a biorefinery platform for effluents and solid wastes valorization - challenges and opportunities.

Due to its physiological and enzymatic features, Yarrowia lipolytica produces several valuable compounds from a wide range of substrates. Appointed by some authors as an industrial workhorse, Y. lipolytica has an extraordinary ability to use unrefined and complex low-cost substrates as carbon and nitrogen sources, aiding to reduce the waste surplus and to produce added-value compounds in a cost-effective way. Dozens of review papers regarding Y. lipolytica have been published till now, proving the interest that this yeast arouses in the scientific community. However, most of them are focused on metabolic pathways involved in substrates assimilation and product formation, or the development of synthetic biology tools in order to obtain engineered strains for biotechnological applications. This paper provides an exhaustive and up-to-date revision on the application of Y. lipolytica to valorize liquid effluents and solid wastes and its role in developing cleaner biotechnological approaches, aiming to boost the circular economy. Firstly, a general overview about Y. lipolytica is introduced, describing its intrinsic features and biotechnological applications. Then, an extensive survey of the literature regarding the assimilation of oily wastes (waste cooking oils, oil cakes and olive mill wastewaters), animal fat wastes, hydrocarbons-rich effluents, crude glycerol and agro-food wastes by Y. lipolytica strains will be discussed. This is the first article that brings together the environmental issue of all such residues and their valorization as feedstock for valuable compounds production by Y. lipolytica. Finally, it will demonstrate the potential of this non-conventional yeast to be used as a biorefinery platform.

Nanotechnologies: An Innovative Tool to Release Natural Extracts with Antimicrobial Properties.

Site-Specific release of active molecules with antimicrobial activity spurred the interest in the development of innovative polymeric nanocarriers. In the preparation of polymeric devices, nanotechnologies usually overcome the inconvenience frequently related to other synthetic strategies. High performing nanocarriers were synthesized using a wide range of starting polymer structures, with tailored features and great chemical versatility. Over the last decade, many antimicrobial substances originating from plants, herbs, and agro-food waste by-products were deeply investigated, significantly catching the interest of the scientific community. In this review, the most innovative strategies to synthesize nanodevices able to release antimicrobial natural extracts were discussed. In this regard, the properties and structure of the starting polymers, either synthetic or natural, as well as the antimicrobial activity of the biomolecules were deeply investigated, outlining the right combination able to inhibit pathogens in specific biological compartments.

Laccases in Food Industry: Bioprocessing, Potential Industrial and Biotechnological Applications.

Laccase is a multi-copper oxidase that catalyzes the oxidation of one electron of a wide range of phenolic compounds. The enzyme is considered eco-friendly because it requires molecular oxygen as co-substrate for the catalysis and it yields water as the sole by-product. Laccase is commonly produced by fungi but also by some bacteria, insects and plants. Due it is capable of using a wide variety of phenolic and non-phenolic substrates, laccase has potential applications in the food, pharmaceutical and environmental industries; in addition, it has been used since many years in the bleaching of paper pulp. Fungal laccases are mainly extracellular enzyme that can be recovered from the residual compost of industrial production of edible mushrooms as Agaricus bisporus and Pleurotus ostreatus. It has also been isolated from microorganisms present in wastewater. The great potential of laccase lies in its ability to oxidize lignin, one component of lignocellulosic materials, this feature can be widely exploited on the pretreatment for agro-food wastes valorization. Laccase is one of the enzymes that fits very well in the circular economy concept, this concept has more benefits over linear economy; based on "reduce-reuse-recycle" theory. Currently, biorefinery processes are booming due to the need to generate clean biofuels that do not come from oil. In that sense, laccase is capable of degrading lignocellulosic materials that serve as raw material in these processes, so the enzyme's potential is evident. This review will critically describe the production sources of laccase as by-product from food industry, bioprocessing of food industry by-products using laccase, and its application in food industry.

Vegetable wastes derived polysaccharides as natural eco-friendly plasticizers of sodium alginate.

In this paper, lemon and fennel wastes were recovered and used as secondary-raw polysaccharide sources. These polysaccharides were exploited as natural plasticizers of sodium alginate (A) based films, in order to improve sodium alginate performances, limited by its fragility, extending its potential application in a cost effective and eco-friendly way. Different green processes, such as maceration (MAC), ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), were carried out for obtaining high yield of lemon and fennel polysaccharides (LP and FP). Actually, HPAE-PAD and TLC analyses evidenced the presence of xyslose, galactose, glucose and rhamnose monomers and galacturonic acid, typical of polysaccharides like pectin and xyloglucan chains. These findings were confirmed by NMR and FTIR spectroscopic analyses. Moreovers, gel filtration chromatography assessed the high molecular weight of recovered polysaccharides, particularly of FP waste fraction. The extracted polysaccharides were used as eco-friendly and cost-effective plasticizers of sodium alginate films (AFP and ALP). DSC analysis evidenced a significant decreasing of glass transition temperature of the polymer, tensile tests showed an enlightened rising of elongation at break and TGA analysis showed a faster degradation kinetics of AFP and ALP films, as expected in a plasticized system.

Analysis of glycosylated flavonoids extracted from sweet-cherry stems, as antibacterial agents against pathogenic Escherichia coli isolates.

The aim of this study was to evaluate the bioactivity of flavonoids extracted from sweet-cherry stems which are often used by a traditional system of medicine to treat gastro-intestinal and urinary tract infections but lacking any consistent scientific evidence; moreover the information about the class of phenolics, their content and the potential bioactivity of such material is very scarce. Thus, in this context, we have set a research study in which we evaluated the profile and content of phenolics extracted from sweet-cherry stems through a conventional (70ºC and 20 min) and ultrasound assisted extraction (40 kHz, room temperature and 20 min). The extracts were phytochemically characterized by using an HPLC-DAD-UV/VIS system and assayed by an in vitro minimum inhibitory concentration (MIC) bioassay against Escherichia coli isolates. Simultaneously, the total antioxidant activities were measured using the 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate (ABTS•+) radical cation assay. Our results indicate that sweet-cherry stems have a high content of sakuranetin, ferulic acid, p-coumaric acid, p-coumaroylquinic acid, chlorogenic acid and its isomer neochlorogenic acid. Their average levels were highly affected by the extraction method used (p<0.001). The same trend was observed for total antioxidant activity and MIC values. The extracts produced with ultrasounds presented both, a higher total antioxidant activity and a lower minimum inhibitory concentration. Statistical analyses of our results showed a significant correlation (p<0.01) of total antioxidant activity and minimum inhibitory concentration with phenolics present in the extracts studied. Thus, we can conclude that cherry stems can be further exploited to purify compounds and produce coproducts with enhanced biologically added value for pharmaceutical industry.

Effects of an acid/alkaline treatment on the release of antioxidants and cellulose from different agro-food wastes.

The present investigation was aimed to evaluate the release of both antioxidants and cellulosic fibre from different agro-food wastes. Cost-effective and easily available agro-food residues (brewers' spent grains, hazelnut shells, orange peels and wheat straw) were selected and submitted to a double-step acid/alkaline fractionation process. The obtained acid and alkaline liquors were analysed for total phenols content and antioxidant capacity. The final fibre residue was analysed for the cellulose, lignin and hemicellulose content. The total phenols content and antioxidant capacity of the acid liquors were higher than the alkaline hydrolysates. Orange peels and wheat straw gave, respectively, the highest (19.70±0.68mg/gdm) and the lowest (4.70±0.29mg/gdm) total phenols release. Correlation between antioxidant capacity of the liquors and their origin depended on the analytical assay used to evaluate it. All the acid liquors were also rich in sugar degradation products (mainly furfural). HPLC analysis revealed that the most abundant phenolic compound in the acid liquors was vanillin for brewers' spent grains, hazelnut shells and wheat straw, and p-hydroxybenzoic acid for orange peels. Wheat straw served as the best raw material for cellulose isolation, providing a final residue with a high cellulose content (84%) which corresponded to 45% of the original cellulose. The applied process removed more than 90% of the hemicellulose fraction in all the samples, while delignification degree ranged from 67% (in hazelnut shells), to 93% (in brewers' spent grains). It was not possible to select a unique raw material for the release of highest levels of both total phenols and cellulose.