Valorisation of side streams from wheat milling and confectionery industries for consolidated production and extraction of microbial lipids

Crude enzymes produced via solid state fermentation (SSF) using wheat milling by-products have been employed for both fermentation media production using flour-rich waste (FRW) streams and lysis of Rhodosporidium toruloides yeast cells. Filter sterilization of crude hydrolysates was more beneficial than heat sterilization regarding yeast growth and microbial oil production. The initial carbon to free amino nitrogen ratio of crude hydrolysates was optimized (80.2 g/g) in fed-batch cultures of R. toruloides leading to a total dry weight of 61.2 g/L with microbial oil content of 61.8 % (w/w). Employing a feeding strategy where the glucose concentration was maintained in the range of 12.2 – 17.6 g/L led to the highest productivity (0.32 g/L∙h). The crude enzymes produced by SSF were utilised for yeast cell treatment leading to simultaneous release of around 80% of total lipids in the broth and production of a hydrolysate suitable as yeast extract replacement

Rhodosporidium toruloides cultivated in NaCl-enriched glucose-based media: adaptation dynamics and lipid production

In the present report and for the first time in the international literature, the impact of the addition of NaCl upon growth and lipid production on the oleaginous yeast Rhodosporidium toruloides was studied. Moreover, equally for first time, lipid production by R. toruloides was performed under non-aseptic conditions. Therefore, the potentiality of R. toruloides DSM 4444 to produce lipid in media containing several initial concentrations of NaCl with glucose employed as carbon source was studied. Preliminary batch-flask trials with increasing amounts of NaCl revealed the tolerance of the strain against NaCl content up to 6.0% (w/v). However, 4.0% (w/v) of NaCl stimulated lipid accumulation for this strain, by enhancing lipid production up to 71.3% (w/w) per dry cell weight. The same amount of NaCl was employed in pasteurized batch-flask cultures in order to investigate the role of the salt as bacterial inhibiting agent. The combination of NaCl and high glucose concentrations was found to satisfactorily suppress bacterial contamination of R. toruloides cultures under these conditions. Batch-bioreactor trials of the yeast in the same media with high glucose content (up to 150 g/L) resulted in satisfactory substrate assimilation, with almost linear kinetic profile for lipid production, regardless of the initial glucose concentration imposed. Finally, fed-batch bioreactor cultures led to the production of 37.2 g/L of biomass, accompanied by 64.5% (w/w) of lipid yield. Lipid yield per unit of glucose consumed received the very satisfactory value of 0.21 g/g, a value amongst the highest ones in the literature. The yeast lipid produced contained mainly oleic acid and to lesser extent palmitic and stearic acids, thus constituting a perfect starting material for “second generation” biodiese

Extraction of Phenolic Compounds from Palm Oil Processing Residues and Their Application as Antioxidants

Nusproizvodi proizvodnje palminog ulja, i to pogača od palminih sjemenki, palmina vlakna, ljuske palminih sjemenki i prazni grozdovi palminog ploda, upotrijebljeni su za ekstrakciju polifenolnih spojeva. Među tim nusproizvodima je pogača od palminih sjemenki sadržavala najviše ukupnih fenolnih spojeva, i to 5,19 mg u g suhe tvari, izraženih kao ekvivalent galne kiseline, dok je najmanje imao prazni grozd palminog ploda, i to 1,79 mg/g. Radi optimiranja ekstrakcije fenola ispitani su sljedeći parametri: vrijeme ekstrakcije i omjer tekuće i krute tvari. Najveći ukupni udjel fenola od 5,35 mg/g pri omjeru tekuće i krute tvari od 40:1 tijekom ekstrakcije od 20 min imala je pogača od palminih sjemenki. Pomoću HPLC-DAD metode određeni su glavni fenolni spojevi iz nusprodukata proizvodnje palminog ulja. Pogača od palminih sjemenki sadržavala je najviše pirogalola, te 4-hidroksibenzojeve, galne i ferulinske kiseline. Prazni grozdovi palminog ploda i palmina vlakna bili su bogati hidroksibenzojevom kiselinom, dok je pirogalol bio dominantan sastojak ekstrakta ljuski palminih sjemenki. Svi su ekstrakti imali oksidacijsku aktivnost, koja je potvrđena DPPH analizom, te ispitana dodatkom ekstrakta suncokretovom ulju radi produljenja roka trajanja. Dodatkom 0,8 % ekstrakta pogače od palminih sjemenki povećalo se indukcijsko vrijeme suncokretovog ulja za više od 50 %. Rezultati istraživanja potvrđuju da je pogača od palminih sjemenki nusproizvod s dodanom vrijednošću koji se može upotrijebiti kao antioksidans u prehrambenoj industriji.The side streams derived from the palm oil production process, namely palm kernel cake, palm pressed fibre, palm kernel shells and empty fruit bunches, were evaluated as sources of phenolic compounds. Among these streams, kernel cake had the highest total phenolic content (in mg of gallic acid equivalents (GAE) per g of dry sample) with a value of 5.19, whereas the empty fruit bunches had the lowest value (1.79). The extraction time and liquid-to-solid ratio were investigated to optimize the phenolic extraction. Kernel cake exhibited the highest total phenolic content (5.35 mg/g) with a liquid-to-solid ratio of 40:1 during 20 min of extraction. The main phenolic compounds of the extracts deriving from all byproduct streams were also identified and quantified with HPLC-DAD. Pyrogallol, 4-hydroxybenzoic acid, gallic acid and ferulic acid were the main compounds found in kernel cake extracts. Empty fruit bunch and pressed fibre extracts were also rich in 4-hydroxybenzoic acid, while pyrogallol was the predominant compound in kernel shell extracts. All extracts showed antioxidant activity as it was indicated from the results of DPPH analysis and subsequently tested in sunflower oil aiming to prolong its shelf life. The addition of 0.8 % kernel cake extract increased the induction time of sunflower oil more than 50 %. According to the results obtained in this study, kernel cake extracts could be considered as a value-added co-product with a potential application as antioxidants in the food industry

Compost stream as a potential biomass for humic acid production: Focus on compost seasonal and geographical variability

Compost is a voluminous stream rich in humic and fulvic acids, which may be recovered as high-added value compounds. These soluble bio-based lignin-like polymeric substances (SBO) can be extracted through a completely green process developed at pilot scale, whose main core is the hydrolytic route in aqueous solutions at relatively mild temperature (< 140 °C) at ACEA Pinerolese Industriale premises. Due to their chemical-physical properties, the SBO compounds can be used with advantage for myriads of industrial applications, from the formulation of detergents to the production of agriculture biostimulants, answering the increasing demand for bio-compound utilization. In view of LIFECAB project (LIFE16 ENV/IT/000179), the characterization of starting materials and the derived compost has been performed over four seasons and over three European countries (Italy, Greece ad Cyprus). In view of establishing a relationship between SBO molecules and compost properties, this work is a challenging opportunity for assessing the compost variability and its temporal evolution during the composting process. Analyses of pH, salinity, total carbon, total nitrogen and C/N ratio, critically assessed by means of a statistical approach, provide important information about compost composition according to the season and to the local environmental conditions

Synthesis and Characterization of Bacterial Cellulose from Citrus-Based Sustainable Resources

Citrus juices from whole oranges and grapefruits (discarded from open market) and aqueous extracts from citrus processing waste (mainly peels) were used for bacterial cellulose production by Komagataeibacter sucrofermentans DSM 15973. Grapefruit and orange juices yielded higher bacterial cellulose concentration (6.7 and 6.1 g/L, respectively) than lemon, grapefruit, and orange peels aqueous extracts (5.2, 5.0, and 2.9 g/L, respectively). Compared to the cellulosic fraction isolated from depectinated orange peel, bacterial cellulose produced from orange peel aqueous extract presented improved water-holding capacity (26.5 g water/g, 3-fold higher), degree of polymerization (up to 6-fold higher), and crystallinity index (35-86% depending on the method used). The presence of absorption bands at 3240 and 3270 cm-1 in the IR spectrum of bacterial cellulose indicated that the bacterial strain K. sucrofermentans synthesizes both Iα and Iβ cellulose types, whereas the signals in the 13C NMR spectrum demonstrated that Iα cellulose is the dominant type

Effect of pearling on dry processing of oats

An innovative oat dry processing, integrating pearling, dry milling and sifting, has been developed. The benefits of applying pearling included the production of bran-rich fractions enriched in specific bran layers and their corresponding chemical constituents, removal of trichomes and harmful surface-borne compounds such as aluminium, and microbial decontamination of pearled oat groats. The surface-borne trichomes of an Expression oat cultivar contained at least 126 ppm aluminium and were inhabited by at least three strains of bacteria up to a population of 380 000 colony forming units per gram of trichomes. A pearling process of 5 s depilated all trichomes, resulting in the complete removal of aluminium and bacteria from pearled oat groats. Chemical analysis of the bran-rich fractions (referred to as pearlings) revealed irregular distributions of minerals and protein, while moisture and starch contents increased with the amount of pearlings removed. Phosphorus analysis in the pearlings indicated that a pearling time interval from 20 to 50 s generated a fraction enriched in aleurone material to a level of 24%

Dry processing of oats – Application of dry milling

A dry milling strategy has been developed for separating oats into bran-rich and starch-rich fractions. For the first time, this process combined the benefits of oat pearling with the efficiency of break and reduction milling and sifting to allow production of flour and bran fractions from an oat cultivar of high lipid content. The bran-rich fraction complies with the separation ratio and chemical composition of the AACC’s definition for oat bran. Oat cultivars with a lipid content below 10% (db) can be dry milled by the process developed in this study. The roll disposition, roll gap and the speed differential of the corrugated and smooth rolls together with the aperture size of the sieves for flour separation were the important parameters that determined the milling and separation efficiency of this oat dry milling process. Critical settings of these parameters included a roll disposition of dull to dull, a roll gap of not larger than 0.1 mm, and a sieve aperture size of 212 μm for flour separation. A pearling step as short as 5 s prior to roller milling effectively removed all the trichomes from the surface of two cultivars of naked oats. This would significantly reduce the health hazards arising from trichomes during oat dry processing

Effect of pearling on dry processing of oats

An innovative oat dry processing, integrating pearling, dry milling and sifting, has been developed. The benefits of applying pearling included the production of bran-rich fractions enriched in specific bran layers and their corresponding chemical constituents, removal of trichomes and harmful surface-borne compounds such as aluminium, and microbial decontamination of pearled oat groats. The surface-borne trichomes of an Expression oat cultivar contained at least 126 ppm aluminium and were inhabited by at least three strains of bacteria up to a population of 380 000 colony forming units per gram of trichomes. A pearling process of 5 s depilated all trichomes, resulting in the complete removal of aluminium and bacteria from pearled oat groats. Chemical analysis of the bran-rich fractions (referred to as pearlings) revealed irregular distributions of minerals and protein, while moisture and starch contents increased with the amount of pearlings removed. Phosphorus analysis in the pearlings indicated that a pearling time interval from 20 to 50 s generated a fraction enriched in aleurone material to a level of 24%