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Volatile fatty acids (VFAs), which can be generated by acidogenesis of organic wastes, are important building blocks for chemicals production, and are intermediates in many bioprocesses such as microbial lipids production. Important factors affecting the bioconversion of VFAs (acetate, propionate and butyrate) by Yarrowia lipolytica W29 and NCYC 2904 for growth and lipids accumulation were studied. Yarrowia lipolytica grew efficiently in VFAs-based media, but lipids production was enhanced by the addition of co-substrates (glucose or glycerol) in batch cultures. A two-stage batch culture growth phase on glucose, followed by VFAs addition improved lipids accumulation. Lipids concentrations of 2.3?g·L-1 and 3.5?g·L-1 were obtained with this mode of operation, with addition of 18?g·L-1 VFAs, for Y. lipolytica W29 and NCYC 2904, respectively. For the first time, it was demonstrated that oxygen mass transfer is a crucial factor for lipids production by Y. lipolytica from VFAs. Intracellular lipids produced by Y. lipolytica strains were mainly composed by oleic and linoleic acids, similar to common vegetable oils, making these lipids suitable for biodiesel production. Moreover, margaric acid, which may improve biodiesel properties, was only detected in propionate medium. The strategies studied herein will contribute to the feasibility of using VFAs as low-cost feedstock for microbial lipids production by Y. lipolytica strains., This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the project TUBITAK 2014 (TUBITAK/0009/2014), the strategic funding of UIDB/04469/2020 unit and Doctoral grants (SFRH/BD/144188/2019; SFRH/BD/129592/2017)., info:eu-repo/semantics/publishedVersion

Consumers are more demanding, better educated in terms of food quality and nutritional aspects, and forcing producers along with regulatory agencies to search for alternative processing technologies. Some of these technologies like high pressure, pulsed electrical fields, supercritical CO 2 , ultrasound, ozone, or plasma treatment are at industrially use, pilot scale, or even at the edge of application, but the most successful ones at the moment, with already a wide variety of commercial products, are high hydrostatic pressure and pulsed electrical fields. These technologies offer better products, both “natural” in terms of fresh-like flavor and ingredients and safe with extended shelf-life. This tendency leads to the need for a global regulation system that ensures quality of food regardless of country of origin and, at the same time, without compromising safety. In addition to this system, there should be governing bodies that regulate and monitor the enforcement of these food-processing regulations, to avoid regulations that often only apply to countries belonging to specific organizations. Together with food legislation concerns, sustainable food manufacturing and related efficient energy use have also became priorities of the food industries. While conventional preservation processes (e.g., canning, freezing, drying) mainly use thermal energy, more complex processes use mechanical, electromagnetic, electrical, and other forms of energy, which can reduce the energy consumption. Indeed the efficient use of resources in food industry is a critical element for the future generations for sustainable food processing, but the impact of energy requirements in emerging technologies has not been a matter of intense discussion. The objective of this chapter is to provide a concise overview of environmental footprint of emerging technologies, namely high-pressure processing and pulsed electric fields, and their current related food legislation status in various countries.

Yarrowia lipolytica, an oleaginous yeast, is an adequate cell factory platform to convert low-value hydrophobic substrates into microbial oils and other important metabolites. The ability of Y. lipolytica W29 to produce microbial oils and other compounds (lipase and citric acid) from waste cooking oils (WCO) and animal fat (lard) was evaluated and the effect of several factors were assessed by an experimental design. OTR and pH was by far the most influential parameters for microbial oils production by Y. lipolytica W29 from lard and from WCO, respectively. Regardless of hydrophobic substrate used, the yeast oil content obtained (58% from lard and 53% from WCO) was one of the higher ever reported for a non-genetically modified Y. lipolytica strain. The unsaturated-to-saturated fatty acids ratio of these microbial oils is higher than in initial substrate, which indicates that they can be interesting as a potential source to food supplements. Besides intracellular lipids accumulation, a simultaneous production of lipase (from WCO) and citric acid and lipase (from lard) was observed, demonstrating that a biorefinery approach may be designed based on fat raw materials, allowing at the same time the reduction of fatty wastes surplus., info:eu-repo/semantics/publishedVersion

Natural aroma additives request increases every year due to consumer demand, thus the biotechnological production of such compounds have gained increased importance. γ-Decalactone is a peach-like aroma widely used in many industrial applications (food, cosmetics, detergents, etc.). -Decalactone production by Yarrowia lipolytica from castor oil (CO) has been studied by many authors in order to improve strains by genetic engineering, as well as to optimize cultures performance by selecting bioreactor operating conditions. In this work, the use of co-cultures (mixed cultures) of two mutant strains derived from Y. lipolytica wild-type W29, MTLY40-2P strain overexpressing POX2 gene and JMY3010 that overexpresses LIP2 gene, was evaluated and compared with pure cultures of each strain. For batch co-culture (mixed culture of both strains) higher -decalactone concentration (1844 ± 46 mg L1) and productivity (80 ± 5 mg L1 h1) were obtained, when compared with pure cultures of each strain. The lipase production by JMY310 strain accelerates the CO hydrolysis and the use of MTLY40-2P strain, minimize -decalactone re-consumption. The optimization of the co-culture performance was further performed at different cellular and CO concentrations in order to maximize aroma productivity., info:eu-repo/semantics/publishedVersion

Yarrowia lipolytica, a strictly aerobic yeast, can produce several added-value products from different carbon sources, including some agro-industrial wastes. Citric acid, extensively used in many industries, can be produced by Y. lipolytica from crude glycerol. Being this an aerobic bioprocess, the oxygen concentration is a key factor in the citric acid production. Thus, a main challenge on bioreactor selection and operation is to provide an adequate oxygen mass transfer rate (OTR) from the inlet gas into the culture medium. Citric acid production by Y. lipolytica from glycerol was accessed using three different bioreactors: a pressurized, an airlift bioreactor and a stirred tank reactor (STR). Increased OTR's were obtained by raising the total air pressure in the pressurized bioreactor, increasing the specific air flow rate in the airlift bioreactor and varying the aeration and agitation rate in the STR bioreactor. An improvement of 40% in citric acid concentration was obtained raising the air pressure up to 2 bar in the pressurized bioreactor, whereas in the airlift bioreactor, a 30% improvement was attained by 50% increase of specific air flow rate and an increase of 7.7-fold was observed raising OTR from 52 to 408 mg L1 h1 using the STR., info:eu-repo/semantics/publishedVersion

Novel processing technologies have been gaining interest among food researchers due to their lower impact on nutritional and sensory properties of the products compared to the conventional thermal techniques. In this chapter some of the most well-studied (eg, high-pressure processing, pulsed electric fields, ohmic heating, microwave, and ultrasound) emerging technologies are briefly reviewed. Most of these technologies have found niche applications in the food industry, replacing or complementing conventional preservation technologies. Thereby, data on commercialization, energy, and microbial safety are presented and discussed with an ultimate goal to explore strategies for their implementation in the food industry. Novel thermal and nonthermal technologies have shown clear environmental benefits by improving the overall energy efficiency of the process and reducing the use of nonrenewable resources. Lastly, studies with specific examples of the implementation of these novel processing technologies in food industry are described, focusing on the application of high-pressure processing and pulsed electric fields to orange juice, milk, and oysters. Higher implementation costs were observed for the emerging processing technologies compared to the conventional processing technologies, which can be explained by the fact that the industrial application of these novel technologies is still under development. In the future the costs are expected to reduce with further technology advances and their increasing implementation in the industry.