Production of Food Aroma Compounds: Microbial and Enzymatic Methodologies

Posljednjih su godina sve veći zahtjevi za prirodnim proizvodima prehrambene industrije ohrabrili nevjerojatne pokušaje razvoja biotehnoloških procesa u proizvodnji aromatskih spojeva. Ovaj revijalni prikaz donosi nova dostignuća iz tog područja, osobito ističući mogućnosti primjene biljnih stanica i mikrobnih kultura te enzimske tehnologije u proizvodnji velikog broja aromatskih sastojaka hrane. Razmatra se i poboljšanje ekonomske isplativosti proizvodnje uzgojem mikroorganizama na čvrstoj podlozi.Over the past few years, the increasing demand for natural products in the food industry has encouraged remarkable efforts towards the development of biotechnological processes for the production of flavour compounds. The present paper reviews the recent major achievements reported in this field, with a special emphasis on the potential lying in plant cell, microbial cultures and enzyme technology for the production of a wide range of flavours. The use of solid-state fermentation as a means to improve economical feasibility of these processes is also considered

Heterogeneous Electro-Fenton as “Green” Technology for Pharmaceutical Removal: A Review

The presence of pharmaceutical products in the water cycle may cause harmful effects such as morphological, metabolic and sex alterations in aquatic organisms and the selection/development of organisms resistant to antimicrobial agents. The compounds’ stability and persistent character hinder their elimination by conventional physico-chemical and biological treatments and thus, the development of new water purification technologies has drawn great attention from academic and industrial researchers. Recently, the electro-Fenton process has been demonstrated to be a viable alternative for the removal of these hazardous, recalcitrant compounds. This process occurs under the action of a suitable catalyst, with the majority of current scientific research focused on heterogeneous systems. A significant area of research centres working on the development of an appropriate catalyst able to overcome the operating limitations associated with the homogeneous process is concerned with the short service life and difficulty in the separation/recovery of the catalyst from polluted water. This review highlights a present trend in the use of different materials as electro-Fenton catalysts for pharmaceutical compound removal from aquatic environments. The main challenges facing these technologies revolve around the enhancement of performance, stability for long-term use, life-cycle analysis considerations and cost-effectiveness. Although treatment efficiency has improved significantly, ongoing research efforts need to deliver economic viability at a larger scale due to the high operating costs, primarily related to energy consumption.Xunta de Galicia | Ref. ED481B-2018/096Ministerio de Economía y Competitividad | Ref. CTM2017-87326-

A grey box model of glucose fermentation and syntrophic oxidation in microbial fuel cells

In this work, the fermentative and oxidative processes taking place in a microbial fuel cell (MFC) fed with glucose were studied and modeled. The model accounting for the bioelectrochemical processes was based on ordinary, Monod-type differential equations. The model parameters were estimated using experimental results obtained from three H-type MFCs operated at open or closed circuits and fed with glucose or ethanol. The experimental results demonstrate that similar fermentation processes were carried out under open and closed circuit operation, with the most important fermentation products being ethanol (with a yield of 1.81 mol mol−1 glucose) and lactic acid (with a yield of 1.36 mol mol−1 glucose). A peak in the electricity generation was obtained when glucose and fermentation products coexisted in the liquid bulk. However, almost 90% of the electricity produced came from the oxidation of ethanol

Culture conditions and investigation of bioreactor configurations for lipase production by rhizopus oryzae

Lipolytic enzymes are the subject of great industrial and academic interest. For this reason, a detailed study of lipolytic enzyme production by the fungus Rhizopus oryzae is tackled, and several steps from plate to shake flasks and bioreactor cultures are investigated in order to propose an optimized strategy to perform the biological process. The suitability of several lipidic compounds and surfactants is assessed. Triton X-100 (5 g/L) gives the highest activities with a maximum value of 6320 U/L which is 10-fold the value attained in cultures without addition of lipidic compounds. As there are almost no studies on bench-scale bioreactors, two bioreactor configurations, stirred tank and air-lift, are investigated to determine the most suitable one to carry out the biological reaction. It is demonstrated that the lipolytic activity is strongly enhanced when a stirred-tank bioreactor is used with a maximum value of 3521 U/L within two days which is clearly higher than the values produced by other recently reported species.XUNTA de Galicia | Ref. PGIDIT06 PXIB314376P

Biodegradation and utilization of waste cooking oil by Yarrowia lipolytica CECT 1240

Biodegradation of waste cooking oil and its application as lipase production inducer in cultures of Yarrowia lipolytica CECT 1240 have been investigated, both in shake flasks and a bench-scale bioreactor. The ability of this strain to degrade the spent oil was evaluated by monitoring COD throughout the cultures, and a remarkable decrease was recorded (almost 90% decrease in oil COD after 3 days in bioreactor). Moreover, the addition of waste cooking oil to the medium led to a significant augmentation in extracellular lipase production by the yeast, compared to oil-free cultures. This confirms the suitability of the studied residue as an inducer of lipase biosynthesis, which is a very interesting fact, from an economic standpoint. These results were confirmed when a fed-batch strategy was proposed. Finally, some properties of the crude enzyme were studied, and compared to the enzymes obtained when non-used oil was added to the medium.Practical application: New strategies to valorize wastes from the food and agro industries are attracting a great scientific interest due to the important advantages offered from an economic and environmental point of view. For this reason, the yeast Yarrowia lipolytica CECT 1240 is proposed for degrading waste cooking oils. This approach entails also another benefit in terms of lipolytic enzyme synthesis, since the addition of used up oils has a lipase inducer effect. The enormous interest in lipases is reflected in the number of applications that they present. The process was successfully carried out both in shake flasks and a bench-scale bioreactor, allowing producing high levels of lipolytic activity at the same time that the COD was diminished up to nearly 90%Xunta de Galicia | Ref. PGIDIT06PXIB314376P