Influence of grinding and pelleting parameters on granulation and physical characteristics of pelleted animal feed

U savremenom uzgoju živine i svinja smeše se retko koriste u praškastom obliku već se uglavnom peletiraju nakon umešavanja pojedinačnih sastojaka. Pri peletiranju dolazi do narušavanja granulacije smeše, odnosno do gotovo potpunog eliminisanja krupnih čestica, kao i do nastajanja velike količine najsitnijih čestica. U okviru istraživanja u ovoj doktorskoj disertaciji ispitivan je uticaj promene odabranih parametara mlevenja i peletiranja na granulaciju čestica od kojih su pelete sačinjene. Cilj je bio da se utvrdi kombinacija parametara koja doprinosi povećanju sadržaja krupnih čestica, što je značajno u ishrani živine, odnosno da se utvrdi kombinacija parametara koja će u što većoj meri uvećati sadržaj čestica srednje veličine i umanjiti udeo najsitnijih čestica, što je značajno u ishrani svinja. Pri tome je određivan i kvalitet peleta, koji ne sme biti značajnije narušen, kao i potrošnja energije pelet prese za koju je poželjno da je što niža. Nezavisni parametri peletiranja bili su granulacija kukuruznog mliva, rastojanje (zazor) između valjaka i matrice pelet prese, debljina matrice pelet prese i sadržaj vode materijala koji se vodi na peletiranje. Istraživanje je podeljeno u dve faze, gde je u prvoj za usitnjavanje primenjen mlin čekićar, a u drugoj mlin sa valjcima. Na oba uređaja prizvedene su po tri granulacije mliva, pri čemu se granulacija ukrupnjava od najsitnijeg mliva dobijenog na mlinu čekićaru do najkrupnijeg mliva dobijenog na mlinu sa valjcima. U prvoj fazi tri granulacije mliva dobijene na mlinu čekićaru su peletirane u kombinaciji sa tri zazora valjci-matrica (0,30; 1,15 i 2,00 mm) i tri sadržaja vode materijala (14,5%, 16,0% i 17,5%), a u drugoj fazi tri granulacije mliva dobijene na mlinu sa valjcima peletirane su u kombinaciji sa tri debljine matrice (24, 30 i 36 mm) i tri sadržaja vode materijala (14,5%, 16,0% i 17,5%). Dakle, u obe faze su varirana tri parametra na tri nivoa pri čemu je primenjen Box-Behnken eksperimentalni dizajn. Zavisno promenljive karakteristike (odzivi) bili su temperatura matrice pelet prese, specifična potrošnja energije pelet prese, udeo prašine u peletama, stepen želatinizacije skroba, tvrdoća, stepen otiranja i nasipna masa peleta, kao i granulacija materijala nakon peletiranja. Za svaki od pomenutih odziva definisan je polinom (model) drugog reda. Dobijeni modeli upotrebljeni su za optimizaciju procesa peletiranja sa ciljem da se postigne željena granulacija peletiranog materijala, uz što bolji kvalitet peleta i uz što manju potrošnju energije. U istraživanju je utvrđeno da mliva sa približno istom vrednošću geometrijskog srednjeg prečnika, dobijena na mlinu čekićaru i mlinu sa valjcima, imaju značajno različitu raspodelu veličine čestica. Na mlinu čekićaru dobija se šira raspodela, sa većim sadržajem najkrupnijih i najsitnijih čestica, u poređenju sa mlinom sa valjcima. Za proizvodnju mliva približno istog geometrijskog srednjeg prečnika, a pogotovo mliva sa relativno sličnom raspodelom veličine čestica, potrošnja energije kod mlina sa valjcima značajno je manja u poređenju sa mlinom čekićarom.                                                                                                                           Potvrđeno je da peletiranje uzrokuje veliki intenzitet usitnjavanja čestica bez obzira na primenjene parametre. Međutim, određene kombinacije parametara mogu doprineti značajnijem očuvanju krupnih čestica. Parametar peletiranja koji najviše doprinosi povećanju udela krupnih čestica u peletama je granulacija mliva koje se upućuje na peletiranje. Što je krupnija granulacija, udeo krupnih čestica u peletama će biti veći. Rezultati optimizacije procesa peletiranja u prvoj fazi ukazuju da je u pogledu proizvodnje peletirane hrane za živinu, kada je poželjno očuvanje određene količine krupnih čestica, potrebno primeniti krupno mlevenje na mlinu čekićaru, uz podešavanje zazora između valjaka i matrice od 2 mm i uz sadržaj vode materijala od 17,5%. U drugoj fazi optimizacijom je utvrđeno da je potrebno koristiti debljinu matrice od 30 mm, najkrupniju granulaciju mliva na mlinu sa valjcima i vlagu od 17,5%. Pri proizvodnji peletirane hrane za živnu povoljnije je koristiti mlin čekićar, s obzirom da je utvrđeno da su čestice mliva dobijenog na čekićaru otpornije na usitnjavanje tokom peletiranja od čestica dobijenih na mlinu sa valjcima što omogućuje očuvanje većeg broja krupnih čestica tokom peletiranja. Povećanje širine zazora valjci-matrica nije poželjno prilikom peletiranja hrane za svinje jer se povećava intenzitet usitnjavanja čestica, a time i udeo najsitnije frakcije čestica. Sličano je i sa povećanjem debljine matrice. U prvoj fazi istraživanja, rezultati optimizacije pokazuju da je u cilju povećanja udela frakcija čestica srednje veličine (630 – 1600 μm), kao i smanjenja sadržaja najsitnijih čestica (< 125 μm), potrebno primeniti najsitnije mlevenje na mlinu čekićaru, najveći sadržaj vode materijala (17,5%), dok zazor između valjaka i matrice treba podestiti da bude nešto veći od 0,30 mm. I u drugoj fazi istraživanja optimizacija je ukazala da je najveći udeo čestica srednje veličine (630 – 1600 μm), kao i najmanji udeo čestica < 125 μm, ostvaren pri peletiranju najsitnijeg mliva dobijenog na mlinu sa valjcima. Pri tome sadržaj vode je potrebno podesiti na 17,5%, dok debljina matrice treba biti oko 28 mm. Pri predloženim optimalnim parametrima peletiranja ostvaren je zadovoljavajući kvalitet peleta, a potrošnja energije pelet prese bila je na prihvatljivom nivou.In modern poultry and swine breeding, animal feed is rarely used in powder form but mainly pelleted after mixing of different ingredients. During pelleting process, granulation of the feed is compromised, i.e. coarse particles are almost completely destroyed and the content of fine particles is strongly increased. This doctoral thesis investigated the impact of changes in selected grinding and pelleting parameters on granulation of particles after pelleting. The goal was to achieve the quantity of coarse particles in pellets to be as high as possible, which is important in poultry nutrition. Another goal was to determine the combination of parameters that will increase, as much as possible, the content of particles medium in size and reduce the share of the smallest particles, which is important in swine nutrition. At the same time quality of the pellets must not be significantly degraded and energy consumption of pellet press should be as low as possible. Independent pelleting parameters were corn granulation after grinding, the distance (gap) between the rollers and the die of pellet presses (roller-die gap), the thickness of the pellet press die (die thickness) and the water content of pelleted material. The study was divided in two stages. In the first stage the corn was ground using a hammer mill and in the second stage, roller mill was used. Three different granulations were produced on both mills. Coarseness of the ground material increased from the finest material produced using the hammer mill to the coarsest material obtained at the roller mill. In the first stage, three different granulations produced at the hammer mill were pelleted in combination with three different roller-die gaps (0.30, 1.15 and 2.00 mm) and three different water contents of material (14.5%, 16.0% and 17.5%). In the second stage three different granulations produced at the roller mill were pelleted in combination with three different die thicknesses (24, 30 and 36 mm) and three different water content of material (14.5%, 16.0% and 17.5%). Thus, three parameters were varied at three levels in both stages and experiments were designed according to Box-Behnken design. Depended variables (responses) were: temperature of the pellet press die, specific energy consumption of pellet press, dust content in pellets, degree of starch gelatinization,  particle size of the material after pelleting. For each of the responses, a second order polynomial model was defined and used for optimization of the pelleting process. It was determined that particle size distribution of material with similar geometric mean diameter, obtained with hammer mill and roller mill, is significantly different from each other. Hammer mill produced higher quantity of the coarsest and the finest particles comparing to roller mill. Energy consumption of roller mill for grinding to similar particle size distribution or similar geometric mean diameter is lower compared to hammer mill. Even though it was determined that secondary grinding of particles during pelleting is inevitable, certain combinations of pelleting parameters may contribute to significant preservation of large particles and to reduction of quantity of small particles. Results of optimization in the first stage indicated that for the production of pelleted poultry feed, when certain amount of coarse particles should be preserved, it is necessary to apply coarse grinding on hammer mill, with the roller-die gap of 2 mm and with material water content of 17.5%. In the second stage it was determined that it is necessary to use die with thickness of 30 mm, coarsest granulation at the roller mill and material water content of 17.5%. In the production of pelleted poultry feed it is better to use a hammer mill since it was found that the particles obtained on hammer mill are more resistant to secondary grinding than the particles obtained with the roller mill. Roller-die gap increase is not desirable during pelleting of swine feed because it increases secondary grinding, and thus the proportion of the smallest particles. Similar effect has an increase of the die thickness. In the first stage of the study, the results of the optimization showed that the largest quantity of medium-sized particles (630 – 1600 μm), and the lowest quantity of the smallest particles (< 125 μm), were achieved with the finest grinding on the hammer mill. At the same time water content of 17.5% should be applied, while the roller-die gap should be close to 0.30 mm. In the second stage of the study, the largest quantity of medium-sized particles, and the lowest quantity of the smallest particles, was achieved with the finest grinding on the roller mill. According to the optimization results, the water content should be set to 17.5%, while die thickness should approx. 28 mm. With the proposed optimal parameters, satisfactory pellet quality was achieved, and energy consumption of the pellet presses was at an acceptable level

Quality of Pelleted Olive Cake for Energy Generation

Olive cake is by-product of olive oil production. This material cannot be stored in original condition for a long time because it has high water content and relatively high portion of oil that causes rapid deterioration. Thus it is necessary to investigate possible methods of remediation of such by-product, where utilization for energy generation presents a useful option. Several studies have been conducted on energy generation from olive cake, however not one that includes pelleting as a pre-treatment. Therefore, the aim of this paper was to determine the chemical composition of different cultivars of olive cake, to produce pellets, and determine their basic quality parameters. The pellets obtained from olive cake had mainly satisfactory results regarding their quality in comparison to standards for fuel pellets. It should be kept in mind that these standards are manly for wood pellets, and therefore some lower criteria could be applied for olive cake and such biomass. The highest amount of residual oil and the lowest amount of protein was found in cultivar ‘Buža’ and produced pellets had the smallest abrasion index (8.15%). Other cultivars had lower oil and higher protein content, and abrasion index higher than 10%. For these cultivars preparation of material (conditioning and/or binder adding) prior to pelleting is necessary. Higher heating value (HHV) and lower heating value (LHV) were not significantly influenced by different chemical composition of cultivars, thus attention should be paid on their influence on pelleting process

DEM analysis of the granular flow in the static mixers

Statičke mešalice se koriste za mešanje pre glavnog procesa mešanja, čime se značajno smanje vreme mešanja i potrošnja energije. U ovom radu, prikazana je upotreba metode diskretnih elemenata (engl. Discrete Element Method - DEM) na modelovanje mešanja granula u različitim konfiguracijama statičkih mešača (korišćene su različite Komax i Ross konfiguracije za mešanje). Za modelovanje protoka fluida primenjena je metoda numeričke mehanike fluida (engl. Computational Fluid Dynamic - CFD), korišćenjem Ojlerovog dvofaznog modela. Povezivanjem rezultata ove dve metode dobija se pouzdan, dovoljno tačan i adekvatan model koji daje rezultate koji odgovaraju eksperimentalnim merenjima. Statičke mešalice se široko koriste u industiji prerade hrane, farmaceutskoj ili hemijskoj industriji. Ovaj tip mešalice se koristi uglavnom kao predmešač, pre glavnog mešanja, pri čemu se značajno smanjuje vreme mešanja i štedi energija. Za potrebe ovog rada, napravljene su statičke mešalice tipa Ross i Komax od providnog pleksiglasa, dizajnirane u CAD paketu, napravljene korišćenjem CNC glodalice. Pošto su napravljeni elementi bili prozirni, praćenje procesa mešanja granula je bilo i vizuelno. Praćene su i analizirane trajektorije, brzine i ubrzanja čestica, u cilju procene kvaliteta procesa mešanja. Glavni cilj ovog članka je da određivanje ponašanja granula koje se gravitaciono transportuju u različitim konfiguracijama mešalica i odabir najbolje konfiguracije mešalice, uzimajući u obzir ukupnu trajektoriju granule, broj elemenata za mešanje i kvalitet dobijene smeše. Rezultati numeričke simulacije statičkih mešalica upoređeni su sa eksperimentalnim rezultatima, a kvalitet mešanja ispitivan je kriterijumom relativne standardne devijacije. Uticaji tipa mešalice i broja elemenata za mešanje na proces mešanja su proučavani analizom varijanse (ANOVA).Static mixer is used for premixing action before the main mixing process, for significant reduction of mixing time and energy consumption. In this article, the novel numerical approach called Discrete Element Method is used for modeling of granular flow in multiple static mixer applications, while the Computational Fluid Dynamic method was chosen for fluid flow modeling. The main aim of this article is to predict the behaviour of granules being gravitationally transported in different mixer configuration and to choose the best configuration of the mixer taking into account the total particle path, the number of mixing elements and the quality of the obtained mixture. The results of the numerical simulations in the static mixers were compared to experimental results, the mixing quality is examined by relative standard deviation criterion. The effects of the mixer type and the number of mixing elements on mixing process were studied using analysis of variance (ANOVA)

DEM analysis of the granular flow in the static mixers

Statičke mešalice se koriste za mešanje pre glavnog procesa mešanja, čime se značajno smanje vreme mešanja i potrošnja energije. U ovom radu, prikazana je upotreba metode diskretnih elemenata (engl. Discrete Element Method - DEM) na modelovanje mešanja granula u različitim konfiguracijama statičkih mešača (korišćene su različite Komax i Ross konfiguracije za mešanje). Za modelovanje protoka fluida primenjena je metoda numeričke mehanike fluida (engl. Computational Fluid Dynamic - CFD), korišćenjem Ojlerovog dvofaznog modela. Povezivanjem rezultata ove dve metode dobija se pouzdan, dovoljno tačan i adekvatan model koji daje rezultate koji odgovaraju eksperimentalnim merenjima. Statičke mešalice se široko koriste u industiji prerade hrane, farmaceutskoj ili hemijskoj industriji. Ovaj tip mešalice se koristi uglavnom kao predmešač, pre glavnog mešanja, pri čemu se značajno smanjuje vreme mešanja i štedi energija. Za potrebe ovog rada, napravljene su statičke mešalice tipa Ross i Komax od providnog pleksiglasa, dizajnirane u CAD paketu, napravljene korišćenjem CNC glodalice. Pošto su napravljeni elementi bili prozirni, praćenje procesa mešanja granula je bilo i vizuelno. Praćene su i analizirane trajektorije, brzine i ubrzanja čestica, u cilju procene kvaliteta procesa mešanja. Glavni cilj ovog članka je da određivanje ponašanja granula koje se gravitaciono transportuju u različitim konfiguracijama mešalica i odabir najbolje konfiguracije mešalice, uzimajući u obzir ukupnu trajektoriju granule, broj elemenata za mešanje i kvalitet dobijene smeše. Rezultati numeričke simulacije statičkih mešalica upoređeni su sa eksperimentalnim rezultatima, a kvalitet mešanja ispitivan je kriterijumom relativne standardne devijacije. Uticaji tipa mešalice i broja elemenata za mešanje na proces mešanja su proučavani analizom varijanse (ANOVA).Static mixer is used for premixing action before the main mixing process, for significant reduction of mixing time and energy consumption. In this article, the novel numerical approach called Discrete Element Method is used for modeling of granular flow in multiple static mixer applications, while the Computational Fluid Dynamic method was chosen for fluid flow modeling. The main aim of this article is to predict the behaviour of granules being gravitationally transported in different mixer configuration and to choose the best configuration of the mixer taking into account the total particle path, the number of mixing elements and the quality of the obtained mixture. The results of the numerical simulations in the static mixers were compared to experimental results, the mixing quality is examined by relative standard deviation criterion. The effects of the mixer type and the number of mixing elements on mixing process were studied using analysis of variance (ANOVA)

Uticaj Bonsilage Plus i Bonsilage Forte na smanjenje mikroflore tokom siliranja lucerke

Crops at ensiling contain both aerobic and anaerobic microorganisms and a range of bacteria and fungi that affect silage quality. Typical classes of microorganisms on plants prior to ensiling are aerobic bacteria, lactic acid bacteria (LAB), enterobacteria, yeasts, molds, clostridia, bacilli, acetic acid bacteria and propionic acid bacteria. The quality of silage depends on the competition between different groups of microorganisms. LAB, which are responsible for the silage fermentation process, usually dominate the silage microflora, but undesirable microorganisms, that occur at low levels on fresh plant material, may grow during the storage of silage and lead to anaerobic or aerobic spoilage. In this study, effects of silage inoculants on reduction of microflora during ensiling of alfalfa have been investigated. The results showed that the addition of commercial silage inoculants, Bonsilage Plus and Bonsilage Forte, had significant effect in reducing total number of aerobic bacteria, enterobacteria, yeasts, moulds and sulphite reducing clostridia during ensiling of alfalfa.Biljni materijal za siliranje sadrži aerobne i anaerobne mikroorganizme i niz bakterija i gljivica koji utiču na kvalitet silaže. Tipične klase mikro-organizama na biljkama pre siliranja su aerobne bakterije, bakterije mlečne kiseline (LAB), enterobakterije, kvasaca, plesni, klostridije, bakterije sirćetne kiseline i bakterije propionske kiseline. Kvalitet silaže zavisi od dominacije različitih grupa mikroorganizama. Bakterije mlečne kiseline, koje su odgovorne za proces fermentacije silaže, obično dominiraju mikroflorom silaže, ali broj neželjenih mikroorganizama, koji se javljaju u niskom nivou u svežoj biljnoj masi, može da raste tokom skladištenja silaže i dovede do njenog kvarenja. U ovom radu je ispitivan uticaj silažnih inokulanata na smanjenje mikroflore u toku siliranja lucerke. Rezultati su pokazali da je dodavanje komercijalnih inokulanata Bonsilage Plus i Bonsilage Forte, imalo značajan efekat na smanjenje ukupnog broja aerobnih bakterija, enterobakterija, kvasaca, plesni i klostridija tokom siliranja lucerke

A review of possibilities for control of Salmonella and other pathogenic bacteria in pig feed

Each category of pigs is susceptible to diseases caused by pathogenic bacteria, which negatively reflects on animal health, farm production results or meat quality. Animal feed is one of the potential reservoirs of pathogenic bacteria and infection source of domestic animals. Salmonella spp. is major microbiological hazard in animal feed. Thus, there is importance for implementation of strategies for preventing feed contamination with Salmonella, by minimizing dust, maximizing hygiene of space and processing equipment in feed mills and implementing control measures in each stage of feed production. Existing Salmonella feed contamination can be eliminated by conditioning and later different heat treatments (pelleting, extrusion, expansion) in production process while changing physical structure of the feed (coarsely or finely ground mash or pellets) can influence on conditions for Salmonella development in gastrointestinal tract of pigs. Contamination of feed by pathogenic bacteria and conditions for their development can be also controlled by addition of acidifiers, prebiotics, probiotics and, more recently, essential oils of plant origin, into feed. Various strategies for prevention of feed bacterial contamination, processes for feed decontamination, as well as possibilities for controlling pathogenic bacteria, especially Salmonella, in pig feed were presented and discussed in this article

A SIMPLE SYSTEM FOR STUDING THE FERMENTATION DYNAMICS OF SILAGES JEDNOSTAVAN SISTEM ZA ISPITIVANJE FERMENTACIONE DINAMIKE U SILAŽI

ABSTRAC

Fatty Acid Composition and β-Carotene Content in Egg Yolk of Laying Hens Fed with Linseed, Paprika and Marigold

Eggs enriched with n-3 fatty acids and natural pigments are desirable in human food chain due to numerous benefits for health. In this study, we investigated the effects of inclusion of co-extruded linseed and sunflower meal into laying hens’ diet and replacement of synthesized pigment with paprika and marigold flower as sources of natural pigments. Four hundred 18–wk-old Bovan laying hens divided in two groups (control and experiment) were fed for 12 weeks. Fatty acids and β-carotene were monitored every fourth week and successively analyzed. Significantly (p<0.05) increased content of α-linolenic acid in egg yolk in the experimental group in comparison to the control group was observed with addition of linseed, paprika and marigold in laying hens’ nutrition. Nearly the same tendency was observed in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content. Supplementation of the co-extruded linseed and sunflower meal into laying hens’ diet demonstrated significantly (p<0.05) lower n-6/n-3 FA ratio in experimental group compared to control group. The obtained results showed that the synthetic pigment added to laying hens’ diet provided better pigmentation of egg yolks after one and two months of the feeding trial than paprika and marigold flower. The concentration of β-carotene in egg yolks increased in experimental group after three months of the treatment, and that was the first time that concentrations of β-carotene did not significantly (p < 0.05) differ among control and experimental group, which shows that paprika and marigold flower as sources of natural pigments can successfully replace synthetic pigment. We shall continue research in this field with other supplemented mixtures, as there are indices for other potential feed enhancements among oily seeds and herbs

Optimization of the classification process in the zigzag air classifier for obtaining a high protein sunflower meal - Chemometric and CFD approach

In this study, sunflower meal is ground by a hammer mill after which air zigzag gravitational air classifier is used for separating sunflower hulls from the kernels in order to obtain protein rich fractions. Three hammer mill sieves with sieve openings diameter of 3, 2 and 1 mm were used, while three air flows (5, 8.7 and 12.5 m(3)/h) and three feed rates (30%, 60% an 90% of bowl feeder oscillation maximum rate) were varied during air classification process. For describing the effects of the test variables on the observed responses Principal Component Analysis, Standard Score analysis and Response Surface Methodology were used. Beside experimental investigations, CFD model was used for numerical optimization of sunflower meal air classification process. Air classification of hammer milled sunflower meal resulted in coarse fractions enriched in protein content. The decrease in sieve openings diameter of the hammer mill sieve increased protein content in coarse fractions of sunflower meal obtained at same air flow, and at the same time decreased matching fraction yield. Increase in air flow lead to the increase in protein content along the same hammer mill sieve. Standard score analysis showed that optimum values for protein content and ratio of coarse and fine fractions have been obtained by using a sieve with 1 mm opening diameter, air flow of 12.5 m(3)/h and 60% of the maximum feeder rate. Fraction ratio and protein content were mostly affected by the linear term of air flow and the sieve openings diameter of the hammer mill sieve in the Second Order Polynomial model. The main focus of CFD analysis was on the particle simulation and the evaluation of the separation efficiency of the zigzag classifier. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved