Jelena Pejin

PROGRESS IN THE PRODUCTION OF BIOETHANOL ON STARCH-BASED FEEDSTOCKS*

Bioethanol produced from renewable biomass, such as sugar, starch, or lignocellulosic materials, is one of the alternative energy resources, which is both renewable and environmentally friendly. Although, the priority in global future ethanol production is put on lignocellulosic processing, which is considered as one of the most promising second-generation biofuel technologies, the utilization of lignocellulosic material for fuel ethanol is still under improvement. Sugar-based (molasses, sugar cane, sugar beet) and starch-based (corn, wheat, triticale, potato, rice, etc.) feedstock are still currently predominant at the industrial level and they are, so far, economically favorable compared to lingocelluloses. Currently, approx. 80 % of total world ethanol production is obtained from the fermentation of simple sugars by yeast. In Serbia, one of the most suitable and available agricultural raw material for the industrial ethanol production are cereals such as corn, wheat and triticale. In addition, surpluses of this feedstock are being produced in our country constantly. In this paper, a brief review of the state of the art in bioethanol production and biomass availability is given, pointing out the progress possibilities on starch-based production. The progress possibilities are discussed in the domain of feedstock choice and pretreatment, optimization of fermentation, process integration and utilization of the process byproducts.

Lactic acid production on liquid distillery stillage by Lactobacillus rhamnosus immobilized onto zeolite.

In this study, lactic acid and biomass production on liquid distillery stillage from bioethanol production with Lactobacillus rhamnosus ATCC 7469 was studied. The cells were immobilized onto zeolite, a microporous aluminosilicate mineral and the lactic acid production with free and immobilized cells was compared. The immobilization allowed simple cell separation from the fermentation media and their reuse in repeated batch cycles. A number of viable cells of over 10(10) CFU g(-1) of zeolite was achieved at the end of fourth fermentation cycle. A maximal process productivity of 1.69 g L(-1), maximal lactic acid concentration of 42.19 g L(-1) and average yield coefficient of 0.96 g g(-1) were achieved in repeated batch fermentation on the liquid stillage without mineral or nitrogen supplementation.

The bioethanol production with the thin stillage recirculation.

In this paper, the bioethanol production with the thin stillage recirculation in mashing was investigated. The mashing was performed with recirculation of: 0, 10, 20 and 30 % of the thin stillage. The thin stillage recirculation was repeated six times. In the experiment without the thin stillage, the recirculation bioethanol yield (compared to the theoretical yield) was 97.96 %, which implicates that the experiment conditions were chosen and performed well. With the addition of the thin stillage, the bioethanol yield increased and was above 100 %. Higher bioethanol yield than 100 % can be explained by the fact that the thin stillage contains carbohydrates, amino acids and yeast cells degradation products. The bioethanol yield increased with the increased number of thin stillage recirculation cycles. Dry matter content in fermenting slurry increased with the increased thin stillage quantity and the number of the thin stillage recirculation cycles (8.04 % for the first and 9.40 % for the sixth cycle). Dry matter content in thin stillage increased with the increased thin stillage quantity and the number of thin stillage recirculation cycles. Based on the obtained results it can be concluded that thin stillage recirculation increased the bioethanol yield. The highest bioethanol yields were obtained with recirculation of 10% thin stillage.

Effect of different fermentation parameters on L-lactic acid production from liquid distillery stillage

Expansion of lactic acid applications, predominantly for the preparation of biodegradable polymers increased the research interest for new, economically favourable production processes. Liquid stillage from bioethanol production can be an inexpensive, valuable source of nutrients for growth of lactic acid bacteria. Utilisation of residual biomass with spent fermentation media as a functional animal feed can greatly influence the process value and its ecological aspect. In this paper, the kinetics of lactic acid and biomass production on liquid stillage by Lactobacillus rhamnosus ATCC 7469 was studied. In addition, the impact of temperature, inoculum concentration, shaking and pH control by addition of CaCO(3) was evaluated. Maximal lactic acid yield of 73.4%, as well as high biomass production (3×10(8) CFU ml(-1)) were achieved under selected conditions (41°C, 5% (v/v) of inoculum, 1% (w/v) of CaCO(3), initial pH of 6.5 and shaking rate of 90 rpm). These results were achieved without supplementation of the stillage with nitrogen or mineral sources.

Antifungal activity of oregano (Origanum vulgare L.) extract on the growth of Fusarium and Penicillium species isolated from food

The effect of the oregano extract (Origanum vulgare L.) on the growth of Fusarium and Penicillium species isolated from cakes and ready-for-use fresh salads from different kinds of vegetables was investigated. The contents of the active component of extract were identified by GC-MS and they include: carvacrol (34.2%), carvone (18.5%), p-cimene (8.05%), thymol (3.74%). The oregano extract showed the ability to reduce mould growth at all applied concentrations. Stronger inhibitory effect on the growth of Penicillium species, contrary to Fusarium, was determined. At extract concentration of 2.50 mL/100 mL, growth of P. aurantiogriseum, P. glabrum and P. brevicompactum was completely inhibited during 14 days of incubation. At the same concentration, growth of Fusarium proliferatum was inhibited by 81.71%, F. oxysporum by 85.84%, F. verticillioides by 86.50%, P. chrysogenum by 86.2% and F. subglutinans by 88.85%.

CONVENTIONAL AND ALTERNATIVE PRINCIPLES FOR STABILIZATION OF PROTEIN AND POLYPHENOL FRACTIONS IN BEER

Beer haze is primarily formed through complexation of protein and polyphenolic beer ingredients. The problem of reducing susceptibility of beer haze formation can be done either by lowering protein and/or polyphenol levels, or by minimizing the molecular size of protein/polyphenols. In experimental part of this work the shelf life of unstabilized beer is being compared with beer stabilized with various standard products, such as PVPP and silica gel. Furthermore, the trials have been made to prove the functionality of a new product consisting of carrageenan and cross-linked PVPP. The method used to determine shelf life was haze forcing test (0/60°C). Extract, alcohol, bitterness, foam, haze, color and pH were also monitored. The test results showed expectedly that combined treatment of beer ensures the highest level of product stability. Through selective stripping of polyphenols and protein fractions it is possible to improve shelf life of beer to a significant extent.

Antifungal activity of the basil (Ocimmum basilicum L.) extract on Penicillium aurantiogriseum, P. glabrum, P. chrysogenum, and P. brevicompactum

This study was aimed at investigating the antifungal potential of basil (Ocimmum basilicum L.) extract against toxin-producing Penicillium spp. (P. aurantiogriseum, P. glabrum, P. chrysogenum, and P. brevicompactum) isolated from food. The basil extract composition was determined by the GC-MS method. The major component identified in the extract was estragole (86.72%). The determination of the antifungal activity of basil extract on Penicillium spp. was performed using the agar plate method. Basil extract reduced the growth of Penicillium spp. at all applied concentration levels (0.16, 0.35, 0.70, and 1.50 mL/100mL) with the colony growth inhibition from 3.6 (for P. glabrum) to 100% (for P. chrysogenum). The highest sensitivity showed P. chrysogenum, where the growth was completely inhibited at the basil extract concentration of 1.50 mL/100mL. The growth of other Penicillium spp. was partially inhibited with the colony growth inhibition of 63.4 % (P. brevicompactum), 67.5% (P. aurantiogriseum), and 71.7% (P. glabrum). Higher concentrations (0.70 and 1.50 mL/100mL) reduced the growth of the aerial mycelium of all tested Penicillium species. In addition, at the same extract concentrations, the examination of microscopic preparation showed the deformation of hyphae with the frequent occurrence of fragmentations and thickenings, occurrence of irregular vesicle, frequently without metulae and phialides, enlarged metulae. The results obtained in this investigation point to the possibility of using basil extract for the antifungal food protection.

New trends and challenges in lactic acid production on renewable biomass.

Lactic acid is a relatively cheap chemical with a wide range of applications: as a preservative and acidifying agent in food and dairy industry, a monomer for biodegradable poly-lactide polymers (PLA) in pharmaceutical industry, precursor and chemical feedstock for chemical, textile and leather industries. Traditional raw materials for fermentative production of lactic acid, refined sugars, are now being replaced with starch from corn, rice and other crops for industrial production, with a tendency for utilization of agro industrial wastes. Processes based on renewable waste sources have ecological (zero CO2 emission, eco-friendly by-products) and economical (cheap raw materials, reduction of storage costs) advantages. An intensive research interest has been recently devoted to develop and improve the lactic acid production on more complex industrial by-products, like thin stillage from bioethanol production, corncobs, paper waste, straw etc. Complex and variable chemical composition and purity of these raw materials and high nutritional requirements of Lare the main obstacles in these production processes. Media supplementation to improve the fermentation is an important factor, especially from an economic point of view. Today, a particular challenge is to increase the productivity of lactic acid production on complex renewable biomass. Several strategies are currently being explored for this purpose such as process integration, use of Lwith amylolytic activity, employment of mixed cultures of Land/or utilization of genetically engineered microorganisms. Modern techniques of genetic engineering enable construction of microorganisms with desired characteristics and implementation of single step processes without or with minimal pre-treatment. In addition, new bioreactor constructions (such as membrane bioreactors), utilization of immobilized systems are also being explored. Electrodialysis, bipolar membrane separation process, enhanced filtration techniques etc. can provide some progress in purification technologies, although it is still remaining the most expensive phase in the lactic acid production. A new approach of parallel production of lactic bacteria biomass with probiotic activity and lactic acid could provide additional benefit and profit rise in the production process.

The influence of technological parameters on malt quality produced from different triticale varieties.

The analysis of eight different triticale varieties, from selective experiments, crop 2007, from Rimski Sancevi (Serbia) location was performed. On the basis of results obtained from triticale and produced triticale malt analysis as well as during micromalting, technological quality of investigated triticale varieties was evaluated. The aim of the work was to determine if the gibberellic acid added during the germination phase had a positive influence on the degradation of triticale grain during micromalting. Based on the obtained results it was concluded that triticale variety has the most important influence on the quality of produced triticale malt.

Effect of yeast storage temperature and flour composition on fermentative activities of Baker's yeast.

Bakers yeast is a set of living cells of Saccharomyces cerevisiae. It contains around 70-72% of water, 42-45% of proteins, around 40% of carbohydrates, around 7.5% of lipids (based on dry matter), and vitamin B-complex. On the basis of yeast cell analysis it can be concluded that yeast is a complex biological system which changes in time. The intensity of the changes depends on temperature. Yeast sample was stored at 4°C i 24°C for 12 days. During storage at 4°C, the content of total carbohydrates decreased from 48.81% to 37.50% (dry matter), whereas carbohydrate loss ranged from 40.81% to 29.28% at 24°C. The content of trehalose was 12.33% in the yeast sample stored at 4°C and 0.24% at 24°C. Loss of fermentative activity was 81.76% in the sample stored at 24°C for 12 days. The composition of five samples of 1st category flour was investigated. It was found that flours containing more reducing sugars and maltose enable higher fermentation activities. The flours with higher ash content (in the range 0.5-0.94%) had higher contents of phytic acid. Higher ash and phytic contents in flour increased the yeast fermentative efficiency. In bakery industry, a range of ingredients has been applied to improve the products quality such as surface active substances (emulsifiers), enzymes, sugars and fats. In the paper, the effect of some ingredients added to dough (margarine, saccharose, sodium chloride and malted barley) on the yeast fermentative activity was studied. The mentioned ingredients were added to dough at different doses: 0.5, 1.0, 1.5 and 2.0%, flour basis. It was found that the investigated ingredients affected the fermentative activity of yeast and improved the bread quality.