Research program
EGG PRODUCTION CHAIN: FROM HEN WELFARE TO QUALITY AND SAFETY OF EGGS AND DERIVED FOOD PRODUCTS
University Co-ordinator
Università degli Studi di BOLOGNA -
SCIENZE DEGLI ALIMENTI - BOLOGNA(BO)
Research Unit Leader
Maria CABONI
Description
The Operative Unit activity will be developed on AGR20 and AGR15 field that will be indicated as action A and B, respectively. There are proposed the egg production and quality evaluation under biological and conventional system; the technological performances and food quality will be evaluated on food chain.Action A: the experiment will be carried out in six different farms located in the centre-north of Italy: three organic farms (according to the Regulation 1804/99) and three intensive conventional farms keeping hens in cages (Control). Both organic and conventional production farms will be chosen according to the same product target, i.e. table eggs rather than egg products. The trial will last 12 months, corresponding to an entire production cycle. Environmental condition of poultry house, productive traits, egg quality and hygiene will be controlled.Environmental evaluations.At 24, 48 and 72 weeks of hen age, dust will be tested and swab of poultry house surfaces will be collected to determine the microbial contamination: 6 pools of 10 different swabs each will be taken from wall, 6 from floor, 6 from cages and 2 samples of dust will be collected close to fans. Each sample will be tested for the Total Microbial Count (TMC), for Enterobacteriaceae, for isolation and identification of Salmonella sp. and in particular Salmonella enteritidis.Productive performances: Hen production (egg number and weight, number of cracked, damaged and dirty eggs, feed consumption) will be evaluated and feed efficiency will be calculated. Morbidity and mortality of hens will be also recorded.Egg qualityAt 24, 48 and 72 weeks of hen age, 100 eggs/farm (600 eggs per each sampling) will be singularly weighted, albumen height will be measured and Haugh index calculated. Eggshell, after oven drying, and yolk will be weighted and by difference albumen weight will be calculated as well as yolk/albumen ratio. In the same eggs the yolk colour will be evaluated according to the CIE L*a*b* system using a Minolta Chromameter (Tallarico et al., 2002). On 10 pools of yolk per farm, fatty acid composition and cholesterol content will be determined by gaschromatography, following the methods reported by Meluzzi et al. (1993, 1997) and calculated the n6/n3 PUFA ratio. Yolk total lipids will be evaluated following the modified Folch method (Folch et al. 1957).Organoleptic traits of boiled or scrambled eggs will be tested using eggs stored for 14 days at room temperature. For each panel test session, 30 untrained panellists, recruited at the Course of Food Science of the UniBO, will be asked to give a preference by using a 7 point hedonic scale (Lawless and Heymann, 1998). Functional properties such as foaming ability and stability of albumen, emulsifying capacity and emulsion stability of yolk will be tested by using eggs stored for 14 days at room temperature. Moreover firmness of vitelline membrane, an important trait responsible of the yolk integrity, will be also measured through a texture analyzer HD 500. In relation to the different intake of antioxidants of birds kept in organic or conventional farms, a particular attention will be paid to the evaluation of lipid oxidation stability of fresh eggs and eggs stored for 14 days at room temperature through the induced TBARS test (Kornburst and Mavis, 1980). Considering that the two rearing systems are quite different in relation either to the use or no-use of medicaments or to the presence of conditioning system, or to the stocking density, or to the effectiveness of pathogen control, particularly those coming from wild animals, the microbial contamination of eggs should be different and related to the rearing system. Therefore the microbial contamination of eggshell of fresh eggs and of edible part of stored eggs will be evaluated. At 24, 48 and 72 weeks of hen age, 50 eggs per farm, divided into 5 pools of 10 eggs each (300 for each sampling) will be tested, by using the washing technique, for the Total Microbial Count and for isolation and identification of Salmonella sp. and in particular Salmonella enteritidis. Moreover to isolate and identify Salmonella sp. in liquid egg of eggs stored at room temperature eggs 2 pools per farm of 10 eggs each (120 eggs for each sampling) will be used. For all microbiological analysis the international standard methods will be used.The hens of both rearing systems (organic and conventional) will be used for physiological evaluation that will be carried out by the research unit of the University of Padova.Since the UO aims to evaluate the entire egg deposition cycle (12 months) and the trial will be carried out in field conditions by involving poultry farms, there are several difficulties in scheduling the sampling time. Therefore the 6 experimental units (3 organic farms and 3 conventional farms) will not start the deposition cycle at the same time. The activity of the first phase (12 months) will be: selection of farms with appropriate deposition cycles, sampling of eggs laid by 24 wk old hens, egg analysis and environmental assay. In the second phase of research (12 months) the remaining samplings and analysis (48 and 72 weeks) will be completed. Moreover the statistical analysis of data will be done.The aim of action B is to identify markers that can permits the classification of dried egg pasta and egg made biscuits, related to the type of raw material (organic and conventional eggs) and processing technology. In particular, this unit will carry out the determinations of the lipid fraction and lipid fraction modifications in each type of considered products: fresh, pasteurized and pasteurized spray dried eggs and egg based products. The operative conditions to obtain pasteurised and pasteurised spray dried eggs on laboratory system will be carried out at the first.Operative Unit UNICB will carry out pasta and biscuits making trials using pasteurized and pasteurized spray dried eggs as ingredients. The first two product can be used according to the pasta production Regulation, whereas the third product is not allowed by this Regulation (DPR 187/2001), but pasta production with egg powder will be performed so as to identify markers that can evidence the presence of this illegal ingredient. In particular, this unit will carried out the following determinations of fatty acids, with respect for peroxide value –trans fatty acids, monoglyceride and diglyceride composition, cholesterol and cholesterol oxidation products, phospholipids and phospholipids reaction products (Utzman, 2000)Depending of the evaluation of organic and conventional production there will be found two types of eggs that are characteristic of each group. Pasteurized and pasteurised spray dry eggs will be obtained and will be tested for pasta and biscuits making; also these trials will be performed by Unit UNICB. Evaluation of the final product (dried egg pasta and biscuits). The effect of pasta processing and drying and biscuit cooking on the quality of the final product will be evaluated , in particular will be assessed the modifications that occur on the lipid fraction. Attention will be focused on the neoformation of some compounds: increase of fatty acids, -trans fatty acids, monoglycerides and diglycerides, cholesterol oxidation products and the degradation of naturally present compounds, such as phospholipids. In addition, the same parameters will be evaluate to determinate the dried egg pasta and biscuits shelf –life, nutritional quality and food safety depending on egg type used. The analytical method request to carried out the planed determinations are relatively complex and both their setting-up than validation are capacity of the Operative Unit. Solid phase extraction (SPE) and thin layer chromatography will be used to fractionate the lipid extract, in some case, after hydrolysis. Capillary columns coated with different stationary phases and film thickness will be used to carried out the following gas chromatographic analysis of fatty acids, monoglycerides and diglycerides, sterols and cholesterol oxidation products. To increase the volatility on each class of compounds a suitable derivatization will be performed. Mass spectrometry permits the structural analysis of the analytes and this technique is request to avoid misidentification, particularly in the case of the cholesterol oxidation products to whom concentration is ranging about ppm. Dry egg pasta, in fact, contains phytosterols - from semolina and a little amount from eggs- which have gas chromatographic retention time similar to these of cholesterol oxidation products. High performance liquid chromatography (HPLC) will be used to carried out phospholipids analysis with a binary gradient. The phospholipid detection, lacking specific chromophore groups, will be made with evaporative light scattering detector (ELSD). It is possible to put on line, before ELSD, UV detector to evidenciate oxidative molecular modification.Phospholipids detection will be carried out also using mass spectrometry that allow also the detection of aminophospholipids linked lo the Maillard reaction products.The statistical elaboration of the data obtained from the Units will be carried out to evaluate by using chemometric techniques. The aim of the elaboration is to discriminate the product obtained using the different raw materials. Objectives of the project:1. To evaluate the productive performance of laying hens kept in different rearing systems (organic method and conventional system in cages);2. To evaluate the effect of rearing system on microbial contamination of poultry house; 3. To evaluate the effect of rearing system on yolk colour of organic and ordinary eggs;4. To evaluate the fatty acid composition, total lipids and cholesterol content of organic and ordinary eggs;5. To evaluate the oxidation stability of lipids of organic and ordinary eggs either fresh or stored;6. To define the organoleptic traits of boiled or scrambled eggs produced either in organic or conventional farms;7. To evaluate the effect of rearing system on microbial contamination of organic and conventional eggs.8. To evaluate how the technology affect the food produced using organic or conventional eggs9. To evaluate the quality of lipidic fraction extracted from food having organic or conventional eggs as ingredient on food chain that comprise technological steps (pasteurisation, spray dry, cooking) and storage.Cited literatureFolch J., M. Lees, and G. H. Sloane-Stanley, 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226: 497-507.Kornburst D. J. and Mavis R. D., 1980. Lipids 15: 315-322.Lawless H.T. and Heymann H., 1998. "Sensory Evaluation of Food". Chapman and Hall (eds.) New York, NY.Meluzzi A., Giordani G., Urrai G.F., Sirri F., Cristofori C., 1993 - Cholesterol level and fatty acid composition of commercial eggs produced in Italy. - Proc. 11th European Symposium on the Quality of Poultry Meat 2: 427-432, Tours, France, 4-8 Octobre.Meluzzi A., Tallarico N., Sirri F., Cristofori C., Giordani G. 1997 – Fortification of hen eggs with n-3 polyunsaturated fatty acids. VII Europ. Symp. on the Quality of Eggs and Egg Products. Poznan (Poland), September 21-26. Pp. 270-277.Tallarico N., Sirri F., Meluzzi A., Pittia P., Parpinello G.P., and Franchini A. (2002) – Effect of dietary vegetable lipids on functional and sensory properties of chicken eggs. Ital. J. Food Sci., 14: 159-166.Utzmann, C.M.; Lederer, M.O. (2000)Identification and quantification of aminophospholipids-linked Maillard compounds in model systems and egg yolk products, J. Agric. Food Chem., 48: 1000-1008.E. Boselli, M.F. Caboni, N.G. Frega e G. Lercker. (2004)Cholesterol oxidation in pasta produced with eggs of different origin. European Food Res.& Technol. In pressE. Boselli, M. Bonoli, M.F. Caboni e G. Lercker. (2002)Determination of cholesterol oxidation products in the supercritical carbon dioxide extract of egg yolk powder: comparison with conventional liquid solvent methods. European Food Res.& Technol. 215, 72-75 E. Boselli e M.F. Caboni;(2000)Supercritical carbon dioxide extraction of phospholipids from dried egg yolk without organic modifier. Journal of Supercritical Fluids, 19, 45-50
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