Streamlined analysis of lactose-free dairy products PDF20160204-573-1JYLU49

Title	Streamlined analysis of lactose-free dairy products
Author	Gertrud Morlock
Pages	9
File Size	2 MB
File Type	PDF20160204-573-1JYLU49
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Journal of ChromatographyA, 1324 (2014) 215– 223 Contentslists availableat ScienceDirect Journal of ChromatographyA j o u r na l hom e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h r o m a Streamlinedanalysisof lactose-freedairy products Gertrud E. Morlock , Lauritz P. Morlock, CarotLemo Chairof FoodScience, Instituteof NutritionalScience, JustusLiebigUniversityGiessen, Heinrich-Buf--ing 26-32,35392Giessen, Germany a r t i c l e i n f o Articlehistory: -eceived1 October2013 -eceivedin revisedform 19 November2013 Accepted20 November2013 Available online 26 November 2013 Keywords: Functionalfood Food safety Food quality control Milk products Carbohydrates Planar chromatography a b s t r a c t Functionalfoodfor lactose-intolerantconsumersandits globalprevalencehascreatedalargemarketfor commerciallyavailablelactose-freefood products.Thesimplestapproachfor detectionandquantitation of lactosein lactose-freedairy productswas developed.A one-stepsamplepreparationwas employed andtheresulting10%samplesolutionwas directlysubjectedto thechromatographicsystem.LODsdown to 0.04mg/Lwere obtainedfor dairyproductsby applicationvolumesup to 250 L on a rectangularstart zone,which is the lowest LODreportedin matrix so far.Thehighly matrix-robust,streamlinedapproach wasdemonstratedfor abroadrangeof dairyproducts,evenwith high fatandproteincontents.Themean recoveryratefor 11 typesof dairy productsspikedat the strictestlactosecontentdiscussed(0.01%) was 90.5±10.5% (n=11).Themeanrepeatabilityfor 11dairyproductsspikedatthe0.01% levelwas1.3±1.0% (n=11).It isthesimplestapproachwith regardto samplepreparationatlow runningcosts(0.3Euroor 0.4 USD/analysis)andfastanalysistime (3 min/analysis).It enabledanef cientproductscreening,andatthe sametime,the quantitationof lactosein relevantsamples.This streamlinedanalysisis highly attractive to the eld of food safetyand quality control of lactose-freedairy products,for which a limit valuefor lactoseis expectedsoon in the EU. This methodologicalconceptcanbe transferredto other challenging elds. © 2013 Elsevier B.V. All rights reserved. 1. Introduction ThetripleA in foodindustry,i.e.availability all over the world at any place and time, addedvalue (functionality), and afordability, is still the pacesetter[1]. Functional food for lactose-intolerant consumer and its global prevalence has created a large market for commercially available lactose-free food products. Lactose- intolerant individuals havea de ciencyof the enzymelactase,and thus, lactose is not completely catabolized into its monosaccha- ride units glucoseand galactose.Lactoseis the major disaccharide found in milk and milk products.The various animal milks contain mostly up to 5%lactose,but for examplehorseandassmilk contain evenup to 7%lactose[2].'Lactose-free' milk and milk productsare mostly producedby breakingdown lactoseinto glucoseand galac- toseby enzymatichydrolysis with ß-galactosidases(often labelled aslactaseon thefood).However,theresultingmilk productsmight contain varying amounts of residual lactose.Lactoseintolerance varieswidely amongindividuals with lactosemaldigestionandthe thresholdof lactoseis highly individual [3].Additionally, especially in the newborn screening, the analysis of galactoseis of inter- est as someindividuals sufer from the geneticmetabolicdisorder Correspondingauthor.Tel.: +496419939141;fax: +496419939149. E-mail addresses: [email protected] (G.E.Morlock), [email protected] (L.P.Morlock), c [email protected](C.Lemo). galactosemia. Suchindividuals donot toleratelactoseandaddition- ally galactose.For example,'lactose-free'milk beverages, in which lactose is enzymatically hydrolyzed to glucoseand galactoseand from which thelatteris not subsequentlyremoved,arenot suitable for patientswith galactosaemia. Hence, it is discussed in Europe, how the lactose content of lactose-free foodproductswill bede ned.Forexample,theworking group Issuesof Nutrition of the German Societyof Food Chemistry (LChG)has recommendedthree categoriesof food declaration[4], i.e.the low in lactoselevelfor food productsof 1%lactose,verylow in lactoselevel ( 0.1%) and lactose-free level ( 0.01% of lactoseand its degradationproducts).The latter is the strictestlevel beingdis- cussed,which permits that thesefood productscan safelybe used in thedieteticmanagementof patientsevenwith galactosaemia, as suchfood productsarealsoindicatedto be'free'of galactose.From the point of view of nutrition and of consumerswith diferent lac- tose thresholds, this 3-level categorizationis rational for nding adequatefood productson the market. However, the German milk industry has a diferent opinion about lactose-freefood products and proposes levels 0.1%[5], which equals to the verylow in lactoselevel discussedbefore and is allowed to containlactosedegradationproducts.Theproduction of lactose-reducedmilk by hydrolysis of lactoseis harmonizedand regulatedby EU law [6], whereasthe production of other lactose- reduced products adhere to national law, which regulatesthat a dairy is only allowed to add the ß-galactosidaseon the authority 0021-9673/$– seefront matter ©2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.chroma.2013.11.038...