Influence of extrusion on the feed value of flax seeds

Relevance. The wide use of extrusion for processing plant raw materials is explained by the possibility of improving the structure and increasing the availability of macronutrients of the target product. Extrusion of oilseeds is complicated by the negative effect of high lipid content on the ongoing physicochemical processes and, as a consequence, a decrease in the quality of extrudates. Along with their high lipid content, oilseeds such as flaxseed contain significant amounts of protein, soluble (mucilage) and insoluble (cellulose, lignin) fibers, which can also affect the technological properties of extrudates. As a high-energy and protein component, flax seeds are used in the feed industry. Increasing the nutritional value of flax seeds and their safety will expand the range of biologically active additives for the production of feed. The purpose of this work is to study the effect of extrusion on the feed value of flax seeds.Methods. For the research we used unmilled oil flax seeds produced in 2020. Flax seeds were processed by wet extrusion: the raw material was preliminarily moistened to 17% at 80 °C; extrusion process parameters — 120 °С, pressure 40 atm., duration 30 sec. Extruded flax seeds were obtained on a pilot plant of OOO “Fid-Group” (Belgorod region). Studies of extruded flax seeds were carried out on the basis of the laboratory for processing bast crops of the Federal Scientific Center for Fiber Crops (Tver).Results. A comparative analysis of the results showed a positive effect of short-term barothermal treatment, such as extrusion, on the chemical composition of flax seeds and their feed parameters. It has been shown that: the content of crude protein in extruded flax seeds increased by 3.97%, the water-soluble fraction increased by 66.18%, which indicates an increase in the biological value of the extrudate; the mass fraction of crude fiber decreased by 1.18%, which indicates an improvement in the digestibility of the extruded product; the content of mineral nutritional value increased by 12.5%; when using barothermal treatment, the nutritional value of flax seeds increased by 2.46%, metabolic energy increased by 2.19% and digestible protein increased by 4.08%; the level of indicators of the lipid complex, acid number and peroxide number, decreased by 40 and 39% respectively, which indicates a decrease in the activity of enzymes that cause hydrolytic and oxidative deterioration of the extrudate.

Kinetics of Anaerobic Digestion of Dairy Fat Waste with Saponification Pre-Treatment

Anaerobic digestion has been an attractive field of research in the era of energy crisis. Biogas, which is the product of anaerobic digestion, provides alternative energy, while at the same time it also prevents pollution due to organic waste accumulation. Among various organic wastes, dairy fat waste is a potential substrate for anaerobic digestion. Fat waste has high theoretical biogas potential because of its high lipid content. However, anaerobic digestion of organic waste with high lipid content is quite challenging. The main obstacle in anaerobic digestion of fat waste is its tendency to form insoluble floating layer on top of the liquid phase. This phenomenon hinders the access of hydrolytic bacteria to the substrate. Saponification is one of the methods to increase the solubility of the floating layer and hence to improve the availability of substrate for the bacteria. Saponification changes the lipid content into soap which has both polar and non-polar functional groups and the polar side will increase the solubility of the substrate in water. This study evaluated the effect of different dosage of base added as the reactant during saponification pre-treatment on the productivity of anaerobic digestion of dairy fat waste. The kinetics of the anaerobic digestion process was analyzed by mean of mathematical model. The variations of the alkaline dosages studied for saponification pre-treatment were 0.04 mol base/g sCOD; 0.02 mol base/g sCOD; and no pre-treatment for control reactor. This study proved that saponification increased the solubility of dairy fat waste. This result was confirmed by the hydrolysis constant value (kH) of 0.00782/day for reactor with saponification, which was twenty times of magnitude higher than the kH value of 0.00032/day in the reactor without saponification. However, the exposure to high pH during the saponification pre-treatment might somewhat inhibit indigenous acidogenic bacteria in the waste which results in lower methane yield in the reactors with saponification to be compared to the control reactor. A B S T R A KPeruraian anaerobik merupakan salah satu bidang riset yang sangat menarik perhatian dalam era krisis energi. Biogas tidak hanya menyediakan energi alternatif, tetapi juga dapat mencegah pencemaran akibat limbah organik. Limbah lemak susu adalah substrat yang potensial untuk proses peruraian anaerobik karena memiliki potensi biogas teoritis yang tinggi akibat kandungan lemaknya yang tinggi. Namun, peruraian anaerobik dari limbah organik dengan kandungan lemak yang tinggi memiliki tantangan tersendiri. Hambatan utama dalam peruraian anaerobik dari limbah lemak susu adalah kecenderungan untuk membentuk lapisan padatan yang tidak larut dan mengapung di bagian atas fase cair. Fenomena ini menghambat akses bakteri hidrolisis terhadap substrat. Saponifikasi adalah salah satu cara untuk meningkatkan kelarutan lapisan padatan tersebut, sehingga meningkatkan ketersediaan substrat untuk bakteri. Saponifikasi akan mengubah kandungan lemak menjadi sabun yang memiliki gugus fungsi polar maupun non-polar. Gugus fungsi yang bersifat polar akan meningkatkan kelarutan substrat dalam air. Studi ini mengevaluasi pengaruh dari berbagai dosis larutan basa yang ditambahkan sebagai reaktan selama perlakuan awal saponifikasi terhadap peruraian anaerobik limbah lemak susu. Kinetika proses peruraian anaerobik dianalisis dengan menggunakan model matematika. Variasi dosis yang diamati pengaruhnya untuk perlakuan awal saponifikasi adalah 0,04 mol basa/g sCOD; 0,02 mol basa/g sCOD; dan nol (tanpa perlakuan awal saponifikasi). Dari penelitian ini, terbukti bahwa saponifikasi berhasil meningkatkan kelarutan limbah lemak susu dan juga ditunjukkan oleh nilai konstanta hidrolisis (kH) 0,00782/hari lebih tinggi dua puluh kali lipat dibandingkan dengan nilai kH 0,00032/hari pada reaktor tanpa saponifikasi. Akan tetapi, penelitian ini juga mengindikasikan bahwa bakteri asidogenik bawaan substrat terhambat kinerjanya oleh paparan pH yang tinggi selama perlakuan awal saponifikasi berlangsung sehingga hasil gas metan yang diperoleh lebih rendah daripada reaktor kontrol.

THE HARVESTING OF HIGH LIPID CONTENT MICROALGAE BIOMASS THROUGH A FLOCCULATION STRATEGY

Different flocculants were evaluated for the flocculation of microalgae biomass of Acutodesmus obliquus. Flocculation was tested with FeCl3 and NaOH at different concentrations and compared to a sample centrifuged at 7000 rpm. The evaluated parameters were absorbance (540 nm) in the clarified medium, and lipids concentration. For FeCl3 (0.2 mmol L-1) as flocculant, efficiency was 96.8%, and with NaOH (8 mmol L-1) 93.5%. Centrifugation efficiency was lower than with either flocculants: 91.7%. However, NaOH flocculation reduced lipid content, which did not occur with FeCl3. Flocculation efficiency was affected by salt concentration, reducing efficiency by 79% due to increased nutrient concentration (9 mL L-1).