Best practices in heterotrophic high-cell-density microalgal processes: achievements, potential and possible limitations

Microalgae of numerous heterotrophic genera (obligate or facultative) exhibit considerable metabolic versatility and flexibility but are currently underexploited in the biotechnological manufacturing of known plant-derived compounds, novel high-value biomolecules or enriched biomass. Highly efficient production of microalgal biomass without the need for light is now feasible in inexpensive, well-defined mineral medium, typically supplemented with glucose. Cell densities of more than 100 g l−1 cell dry weight have been achieved with Chlorella, Crypthecodinium and Galdieria species while controlling the addition of organic sources of carbon and energy in fedbatch mode. The ability of microalgae to adapt their metabolism to varying culture conditions provides opportunities to modify, control and thereby maximise the formation of targeted compounds with non-recombinant microalgae. This review outlines the critical aspects of cultivation technology and current best practices in the heterotrophic high-cell-density cultivation of microalgae. The primary topics include (1) the characteristics of microalgae that make them suitable for heterotrophic cultivation, (2) the appropriate chemical composition of mineral growth media, (3) the different strategies for fedbatch cultivations and (4) the principles behind the customisation of biomass composition. The review confirms that, although fundamental knowledge is now available, the development of efficient, economically feasible large-scale bioprocesses remains an obstacle to the commercialisation of this promising technology

ACTA CHROMATOGRAPHICA

The amounts of three flavonoids, quercetin, kaempferol, and myricetin, in tomatoes (Solanum lycopersicum L.) and tomato-based products produced in Turkey has been determined by reversed phase high-performance liquid chromatography (RPHPLC) with UV detection. The HPLC profiles of five types of tomato, one commercial composite tomato juice, and three types of tomato paste, were obtained after acid hydrolysis and extraction. The presence of the flavonol aglycons was confirmed by gas chromatography with mass spectrometric detection (GC-MS). Tomatoes and tomato-based products contained primarily quercetin, kaempferol, and the minor flavonol myricetin. The total flavonol aglycon content of different varieties of tomato varied from 3.1 to 10.0 mg kg(-1) of fresh weight. Tomato juice and tomato salsa were rich in total flavonols, containing 19.8 mg L-1 and 10.5-13.2 mg kg(-1), respectively. The method enabled accurate and reproducible quantitative analysis of these flavonols in tomatoes and tomato-based products

JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

The contents of potentially toxic elements lead and cadmium and the essential element copper in various milk and dairy products consumed in Turkey were determined by differential pulse polarography (DPP), primarily to assess whether the intakes comply with recommended desired concentrations for essential and permissible levels for toxic elements. A simple and rapid DPP method has been developed for the simultaneous determination of cadmium, lead, and copper in samples. Using the differential pulse mode, half-wave peak potentials as E-1/2 were -0.58, -0.40, and -0.07 V for cadmium (Cd), lead (Pb), and copper (Cu), respectively. Marketed formulations of dairy products have been analyzed by calibration and standard addition methods. Recovery experiments were found to be quantitative. The linear domain ranges were 0.00-674.28 mug/L for Cd (R-2 = 0.9999), 0.19-2.94 mg/L (p < 0.01) for Pb (R-2 = 0.9997), and 0.41 -133.46 mug/L for Cu (p < 0.01) (R-2 = 0.9999). The studies have shown that the method is a rapid, reproducible, and accurate determination of these elements in milk and dairy products and can be used in the analysis of marketed formulations in the milk and dairy industry

V INTERNATIONAL SYMPOSIUM ON PISTACHIOS AND ALMONDS

Nuts contain bioactive constituents that elicit cardio-protective and anticancer effective containing phenolic compounds, healthy lipids, tocopherols, sterols and squalene. This study was undertaken to identify some bioactive constituent levels of almonds (Prunus amygdalus L.) consumed in Datca, Aegean Area, Turkey markets and pistachio (Pistacia vera L.) nuts consumed in Aegean Area, Southeastern Anatolia, Turkey markets. Total lipids, fatty acid (FAs) profiles, tocopherols, sterols and oil stability were determined on the oil extracted from the fresh nuts. Lipid content of the nuts varied between 41.2-59.8% (p<0.05) and the peroxide values (PV) of the fresh oils were 0.13-3.48 meq O-2/kg oil (p<0.05). Mean monounsaturated fatty acid (MUFA) contents of almonds and pistachios were found 70.46 +/- 0.67 and 62.36 +/- 0.61 as % of total lipid, respectively. The major MUFA was oleic acid (C18:1) (42.3-69.8%) while linoleic acid (C18: 2) (21.76-32.13%) was the most prevalent polyunsaturated fatty acid in almonds and pistachios. The PUFA levels ranged from 21.07-32.61 % (p<0.05). Unsaturated FAs / saturated FAs ratio was detected as 10.9 and 9.94 for almonds and pistachios, respectively. The major tocopherol was alfa-tocopherol in almonds (36.8 +/- 4.7 mg/100 g oil) whereas gamma tocopherol level was major in pistachios (37.3 +/- 3.4 mg/100 g oil) (p<0.05). The major sterol was identified as beta-sitosterol and its content was avg. 2155.2 +/- 11.3 mg/g oil in almonds while that of content was 4706.5 +/- 73.2 mg/g oil in pistachios (p<0.05). Total phenolics (TPs) of almonds with skin, TPs of almonds without skin and TPs of pistachios were avg. 313.6 +/- 1.28; avg. 57.44 +/- 1.1; avg. 922.6 +/- 2.8 as mg of gallic acid equivalent (GAE)/100 g, respectively. All data obtained from almond and pistachios was evaluated by multivariate analysis using SPSS (ver.13.0) statistical package program. Almond and pistachios were differantiated with good separation based on the functional lipids, lipid constituents and total phenolic contents via Principal Component Analysis (PCA). In this context, almonds and pistachios can be consumed as good energy snacks in daily nutrition and the multivariate techniques can differentiate these nuts based on their oxidative stability, lipid profiles and total phenolics

JOURNAL OF FOOD SCIENCE

Nutritional composition was determined for Spirulina platensis, Chlorella vulgaris, and Isochrisis galbana cultures. Data include the proximate composition, energy value, mineral elements, and fatty acid composition. Sixteen strains of these microalgae were obtained as a percentage of total fat. Total PUFA, SFA contents, n-3/n-6 ratios, and eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) ratios were obtained. Protein content was high in Spirulina samples, whereas Isochrisis had the highest ash content. Spirulina is a rich source of gamma-linolenic acid (GLA); Chlorella was an important source of PUFAs. Spirulina is a rich source of K, Chlorella is rich in P, and Isochrisis is a good source of Ca and Mg. Se content of Isochrisis is higher than in the other microalgae

JOURNAL OF FOOD SCIENCE AND TECHNOLOGY-MYSORE

The proximate composition, amino acid contents and fatty acid (FA) profiles of flours prepared from 14 sesame (Sesamum indicum L.) seed grown in Turkey were determined. Sesame seed flours (SSF) contained high value of crude protein in the range of 19.12 to 25.35% (p<0.01). Digestible protein concentration was also high (16.88-25.35%) (p<0.01). Ether extracts were 51.05-60.81% (p<0.01). The moisture contents were in the range of 3.10-4.60 (p<0.01) and the ash contents ranged from 2.88 to 5.28% (p<0.01) while crude fiber ranged between 3.86 and 5.16% (p<0.01). Total carbohydrate varied from 5.24 to 9.84% (p<0.01). Reducing sugars were 3.96-6.87% (p<0.01). Essential amino acid contents of SSF were of high levels. SSF are good sources of methionine (3.18-3.62 g/16 g N), lysine (2.23-4.62 g/16 g N), cysteine (2.93-3.88 g/16 g N) (p<0.01).Fatty acids, (C14:0, C16:0, C16:1n-7, C18:0, C18:1n-9, C18:2n-6, C18:3n-3 C20:0, C20:1) of these flours were obtained in percentage of total fat (0<0.01). Linoleic acid was the major unsaturated fatty acid (41.65-44.97%) and polyunsaturated fatty acid (PUFA) contents were high (p<0.01). The SSF are functional foods for nutrition and utilization