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Evaluation of Iberian pig carcasses based on NIR spectra of pork loins The software used for obtaining and chemometric analysis of the spectral data was WINISI II
Evaluation of Iberian pig carcasses,based on NIR spectra of pork loins. E De Pedro M J De La Haba N Nu ez J Garc a and A Garrido. Department of Animal Production Faculty of Agriculture and Forestry Engineering. University of Cordoba P O Box 3 048 14080 C rdoba Spain. Servicio Central de Apoyo a la Investigaci n University of Cordoba Spain. SUMMARY The objective of this paper is to develop multivariate models based on NIR spectral data from. Iberian pork loins to determine the quality of the carcass The official methods to evaluate carcass quality have. different limitations Thus it is necessary to find new methods to classify carcasses according to their feeding. regime Near Infrared Spectroscopy NIRS allows quick analysis to be obtained with low cost per sample high. accuracy and easy handling Loin samples were taken from Iberian pigs The feeding regime was exclusively. grass and acorn for 104 days B1 and 83 days B2 grass and acorns supplemented with a commercial. compound feed during the last 13 days R and only commercial compound feed C Lineal discriminant analysis. was used to obtain a multivariate model based on NIR spectra The model results show that all the samples from. group C were correctly classified, Keywords Iberian pork NIRS carcass classification multivariate model. RESUME Evaluation des carcasses de porc Ib rique bas e sur les spectres NIR des longes de porcs Ce travail. a pour objectif de d velopper des mod les bas s sur des donn es spectrales NIR de longe de porc Ib rique pour. d terminer la qualit des carcasses Les m thodes officielles pour valuer la qualit des carcasses ont certaines. limitations C est pourquoi il est n cessaire de chercher de nouvelles m thodes de classification des carcasses en. correspondance avec leur r gime alimentaire La Spectroscopie dans le Proche Infrarouge NIRS permet de r aliser. des analyses rapides avec un bas prix par chantillon avec pr cision et manipulation facile Les chantillons ont t. pris de la longe de porc Ib rique Le r gime alimentaire a t p turage et gland exclusivement 104 jours B1 83 jours. B2 p turage et gland compl t avec aliment compos commercial les 13 derniers jours R et seulement aliment. compos sp cial C Avec une analyse discriminante lin aire il a t obtenu un mod le multivari bas sur les. spectres NIR Les r sultats du mod le montrent que tous les chantillons du groupe C ont t correctement class s. Mots cl s Porc Ib rique NIRS carcasses mod le multivari. Introduction, The final fattening stage of Iberian pigs can be achieved in three possible ways just using the. natural resources from the dehesa supplementing these resources with commercial compound. feeds and just using commercial compound feeds Animals fattened in this way are classified using. the following commercial categories Bellota Recebo and Cebo respectively. Since pigs are monogastric and therefore the lipids in food are deposited in their tissues without. being modified the fat taken from animals fattened in each of the three aforementioned ways will differ. in its composition Furthermore since lipids are largely responsible for the flavour properties in meat. the qualities of each of these categories will be different Bellota products are the highest quality. which implies higher market prices, The difficulty in carrying out strict controls of the food ingested by animals in the countryside led to. the differentiation of different carcasses based on the main fatty acid values palmitic stearic oleic. and linoleic determined by gas chromatography of an average sample of subcutaneous adipose. tissue taken from a random selection of animals, The higher prices that products in the Bellota category command has led to the appearance of. commercial feed that when given to the animals gives a similar fatty acid deposit composition to that. of animals fattened with acorns However this similarity in fatty acids does not produce the same. sensorial quality as in bellota quality products,Options M diterran ennes Series A No 76 219. Our increasing concern regarding quality traceability and food safety means that the quality control. systems of these products need to be modernised and automated both at the level of the farms. industry and related services, As an alternative to traditional analysis methods new analytical technologies are emerging including. Near Infrared Spectroscopy NIRS In the Animal Production Department of ETSIAM Faculty of. Agriculture and Forestry Engineering in Cordoba several R D projects have been carried out. related to the study of factors that affect production quality of carcasses and products derived from. Iberian pigs using such technology, NIRS technology based on near infrared absorbance offers the possibility of fast analysis with. low cost per sample and also has other highly important features to respond to current requirements. both at an industry and consumer level such as accuracy versatility multiproduct and multiconstituent. easy handling and of course it is a non polluting technique Garrido et al 1996. This technology can perform both quantitative and qualitative analyses Currently we have great. expectations regarding the application of qualitative analysis thanks to the advances in instrumentation. computer development and improvements in the treatment of spectral data This analysis enables. large amounts of samples to be classified in a short period of time by generating classification. models using spectral information, Hence the objective of this paper is to develop a qualitative model based on spectral characteristics. in near infrared of Iberian pork loins for the classification of carcasses according to the animal s. feeding regime,Material and methods,Experimental material. Four batches of 40 Iberian pigs were used whose feeding regime in the final fattening stage is. shown in Table 1, Table 1 Feeding regime of the Iberian pigs during the final fattening stage. Batch Duration of fattening stage Feeding regime,B1 104 Only grass and acorns. B2 83 Only grass and acorns,R 72 7 days acorns 2 kg commercial feed. 16 days only acorns,35 days acorns 2 kg commercial feed. 14 days commercial feed ad limitum, C 115 Special commercial feed that simulates acorn quality. Once the animals had been slaughtered the loins were separated from the carcass and a sample. was taken 80 g from the anterior end of each of them so that only the Longissimus dorsi muscle. was included without any external or intermuscular fat. They were then packaged and refrigerated and transported to the Department of Animal Production. Laboratory where the spectra of each sample were obtained. Analysis equipment, The equipment used to obtain the spectra was a Foss NIRSystems 6500 SY I scanning monochromator. equipped with a spinning cup working in reflectance mode in the spectral range 400 2500 nm at. 220 Options M diterran ennes Series A No 76, intervals of 2 nm This equipment has standard circular capsules to analyse solid products reflectance. readings with a quartz glass window of 3 75 cm diameter. The software used for obtaining and chemometric analysis of the spectral data was WINISI II. version 1 04 Infrasoft International The instrumentation and NIRS software used are the property of. the Central Research Support Service SCAI of the University of Cordoba. Preparation of the sample and spectra collection, The samples were minced until a homogeneous paste was achieved Then the capsules were. filled avoiding the formation of air pores or the presence of connective tissue fibres in contact with the. glass Mart nez et al 1998 and then the spectra of each subsample were obtained. Qualitative analysis, In order to develop the discriminant model we used WINDISCRIM software which classifies the. samples according to how close they are to the model The models are determined by analysing the. main components in which the original variables are the absorbency values for each wave length of. the spectra In this paper we have followed recommendations of Downey 2000 which set the limit. for a sample s belonging to a determined category at 1 5. Batch quality criteria, According to the information collected from the countryside average weight gain of the animals. and type of food consumed the batches would be classified into Bellota batches B1 and B2. Recebo batch R and Cebo batch C, To classify the batches according to the Official Sales Contract OSC of Iberian pigs in force when. the tests were carried out BOE 2000 a sample of fat from each carcass at the slaughterhouse was. taken from the dorsal area in the animal rump, The content of palmitic acid C16 0 stearic acid C18 0 oleic acid C18 1 and linoleic acid. C18 2 was determined using NIR spectroscopy applying the methodology and prediction equations. developed by Garc a Olmo 2002,Results and discussion. Table 2 shows the average fat composition of each batch and the corresponding quality depending. on the levels established in the Official Sales Contract OSC BOE 2002 for the average subcutaneous. fat composition, Table 2 Average composition and standard deviation of the subcutaneous fat of the experimental. batches and their classification according to the OSC criteria. Batch Fatty acid Classification,Palmitic Stearic Oleic Linoleic. x sd x sd x sd x sd,B1 19 6 1 0 9 1 0 9 55 4 1 7 9 3 0 8 Bellota. B2 20 2 0 8 9 8 0 6 54 4 1 3 9 3 0 5 Recebo,R 22 1 0 9 11 1 0 8 50 5 1 4 9 5 0 6 Cebo. C 22 2 1 0 11 0 0 9 50 5 1 3 9 1 0 7 Cebo,Options M diterran ennes Series A No 76 221. As we can see in Table 2 only in the case of batches B1 and C would the classification based on. the field information agree with that based on the OSC analytical criteria In the case of batch B2 this. would be classified in the RECEBO category since it exceeded 9 8 by three decimals the limit. percentage of stearic acid established in the OSC 9 5 which is extremely strict. In the case of batch R which according to the field information should be in the RECEBO. category because of its use of acorn foraging and then commercial feed consumption the analytical. results clearly show a fatty acids profile characteristic of animals in the CEBO class This is probably. the consequence of low acorn consumption and significant contributions of commercial feed. It is important to highlight that the classification of the batches was carried out based on the. average composition Given the variability between the groups as the standard deviations in Table 2. show not all the animals would fit the profile of the category into which the batch has been classified. The high cost and time necessary to perform a gas chromatography analytical determination of the. samples on an individual basis makes this option unviable. With the spectral information of the loin samples a linear discriminant analysis model was obtained. The results are shown in Table 3, Table 3 Classification matrix of the model developed with the NIR spectral. information of the Iberian pork loins using linear discriminant analysis. Batch reference Number of samples classified in the batch. B1 37 0 3 0,B2 1 38 1 0,R 0 3 37 0,C 0 0 0 40, As we can see in Table 3 no samples from batches B1 B2 and R were classified in category C. Furthermore all the samples from batch C were correctly classified in their groups The erroneous. classification of some samples from batches B1 B2 and R into different batch categories could be. due to variation in the animals with regards their feeding behaviour This feeding behaviour would. cause animals to have a higher or lower consumption of acorns grass or commercial feed which. would be reflected in different fat characteristics and a certain similarity with specimens from other. batches However this would not imply an erroneous classification but rather recognition of the greater. or poorer quality of these specimens, However if we accept erroneously classified samples as an error in the model the accuracy. achieved by this methodology is high 95 bearing in mind that it has been applied to individual. samples and not to the batch as a whole, Therefore NIRS technology can be applied to the recognition of the individual quality of Iberian. pork loins Furthermore this technique is more accurate fast and economic than fat composition. analysis using gas chromatography,Aknowledgments, This study was supported by the grant 1FD97 1252 from de Spanish Ministry of Science and. Technology The autors thank the collaboration of E Di guez P Ca uelo L Sili M C Valdovinos and. J Rodriga ez and the facilities from S nchez Romero Carvajal S A. 222 Options M diterran ennes Series A No 76,References. BOE 2000 Orden de 19 de octubre de 2000 por la que se homologa el contrato tipo de compraventa. de cerdos Ib ricos cebados con destino a sacrificio y elaboraci n que regir hasta el 31 de agosto. de 2001 Bolet n Oficial del Estado de 258 de 27 de octubre de 2000. Downey G 2000 Discrimination et authentification des aliments et des ingr dients alimentaires par. spectroscopie dans l infrarouge proche et moyen In La spectroscopie infrarouge et ses applications. analytiques Bertrand D and Dufour E eds Editions TEC DOC Paris France pp 397 422. Garc a Olmo J 2002 Clasificaci n y autentificaci n de canales de cerdo Ib rico mediante espectroscop a. en el infrarrojo cercano NIRS PhD Thesis University of C rdoba Spain. Garrido A G mez A Guerrero J E and Fern ndez V 1996 NIRS Una tecnolog a de apoyo para. un servicio integral en Alimentaci n Animal In Avances en Alimentaci n y Nutrici n Animal De. Blas C Mateos G G and Rebollar P G eds FEDNA Madrid Spain pp 275 300. Mart nez M L Garrido A De Pedro E J and S nchez L 1998 Effect of sample heterogeneity on. MIR meat analysis the use of the RMS statistic Journal of Near Infrared Spectroscopy 6 313 320.