User's Guide of the Inter-Batch Physico-Chemical Variability Calculator

Transcription

1 User's Guide of the Inter-Btch Physico-Chemicl Vribility Clcultor Scope The Inter-Btch Physico-Chemicl Vribility (IBPCV) Clcultor enbles to test if the beteenbtch vribility of the physico-chemicl chrcteristics of food ( nd ) hs significnt impct on the mximum groth rte of bcteri. This clcultor is design to be used in the groth re of the studied bcteri. This groth re is restricted by the crdinl vlues of the bcteri (min - mx nd min - mx). The use of this clcultor, previously requires to hve vilble dt ( nd vlues) to chrcterize the btches. Use of the IBPCV clcultor 1. Input dt relted to the food, the bcteri nd the temperture of the test (blue zones) 1.1 Food dt The first column nmed "Btch" refers to the number of btches tht could be tested. To ssess the beteen-btches vribility, it is recommended to chrcterize t lest btches. As reminder rning ppers in red ("it is recommended to compre t lest btches") if dt from only 2 btches re filled in. The mximum number of btches to be tested by the IBPCV is 2 btches. The food needs to be chrcterized by to physico-chemicl prmeters: nd. To estimte the chrcteristics of btch it is necessry to mesure these prmeters on more thn one smple (idelly more thn 1 smples). Ech btch is therefore chrcterized by men vlues for nd. So, in column "" nd "Mesured ", enter the men initil vlues for nd of the food. These initil vlues noted "vlues t D" correspond to vlues mesured the dy of the mnufcture of the food.

2 It is recommended to use men vlues ith only one deciml nd men vlues ith to decimls. To void using the IBPCV clcultor ith or men vlues loer thn the crdinl vlues of the studied bcteri, to rning ere included (" men min" nd " men min"). Regrding the ter ctivity () no dt is vilble but the initil NCl nd initil moisture contents hve been mesured, the men vlues of these to prmeters cn be filled in column "NCl" nd "moisture". The IBPCV clcultor ill clculte n vlue ccording to the formul of Resnik nd Chirife (1988), given in the EURL Lm technicl guidnce document: = x WPS.1226 x WPS 2 ith WPS content (in g/1ml) = NCl content (in g per 1g) moisture content (in ml per 1g) x 1. Be creful, this formul cn be used for food product here NCl is the min component responsible for the of the food. The lst column lbeled "" gives the initil men vlue of the product (mesured or clculted dt) tht is used for the inter-btch vribility clcultion. For the clcultions, the system prioritizes the mesured vlues rther thn the clculted. 1.2 Dt bout crdinl vlues of the bcteri Input the crdinl vlues (Xmin - X - Xmx) for temperture, nd of the considered bcteri. You my refer to dt proposed in tble 1 (ANSES reference) belo. It is recommended to use temperture vlue s hole number, ith one deciml nd vlue ith to decimls.

3 Tble1: Crdinl vlues for temperture, nd of the food pthogenic bcteri. T min T T mx min mx min mx ( C) ( C) ( C) L. monocytogenes Slmonell spp S. ureus E. coli 157/H / Bcillus cereus / vegettive cells 4 (1 for emetic strins) / Cl. perfringens / / Cl. botulinum/ (proteolytic A nd B) Cl. botulinum/ (non proteolytic B) / / Cl. botulinum/(e) / 1. Storge temperture dt Input the temperture t hich the chllenge test is plnned to be performed. The input vlue is hole number nd lys inferior to the T of the studied microorgnism. A rning ppers if the storge temperture of the test is belo Tmin or over T of the studied bcteri.

4 2. Anser of the clcultor (in red) From the physico-chemicl input dt chrcterizing the product, from the crdinl vlues of the bcteri nd the storge temperture of the chllenge test, the IBPCV clcultor ill conclude on the impct of the vribility of nd on the groth rte of bcteri in the tested condition of the chllenge test. The nser is either "The impct of the vribility of nd is significnt in the tested temperture conditions" or "The impct of the vribility of nd is not significnt in the tested temperture conditions." It is importnt to underline tht hen or vlues of the tested product re close to the groth/no groth boundries of the bcteri, slight chnges in or vlues could hve significnt effect on the groth rte of the bcteri, leding to the conclusion "The impct of the vribility of nd is significnt in the tested temperture conditions". References ANSES, Dt sheets on foodborne microbiologicl hzrds EURL Lm Technicl guidnce document for conducting shelf-life studies on Listeri monocytogenes in redy-to-et-foods, EURL for Listeri monocytogenes, (214) NF V1-9 (mi 214), Lignes directrices pour l rélistion de tests de croissnce microbiologiques. Regultion (EC) 27/25 on microbiologicl criteri for foodstuffs (25) OJ L , p. 1 Resnik SL, Chirife J Proposed theoreticl ter ctivity vlues t vrious tempertures for selected solutions to be used s reference sources in the rnge of microbil groth. J. Food Prot. 51:419 42

5 Annex Clcultion æ Clculte: j T = T -T ö ç èt -T min ø T ( C) being the temperture used for the chllenge test (T T), Tmin ( C) nd T ( C) being respectively minimum groth temperture nd imum groth temperture of the studied bcteri. If <, clculte: ( ) æ - - 2s ö ç j,s = ç - è min ø nd,i 2s min 2s 2s being the beteen-btch men of the food, s being the beteen-btch stndrd devition for the of the food, min nd being respectively minimum nd imum for groth of the studied bcteri. If, clculte: 2s,s nd,i 2s mx mx 2s 2s mx being the mximl for groth of the studied bcteri.

6 If, clculte: ( ) æ j = - - 2s ö ç,s ç - è min ø nd,i 2s min 2s 2s being the men beteen-btch men of the food, s being the beteen-btch stndrd devition for the of the food, min nd being respectively minimum nd imum for groth of the studied bcteri. If, clculte: 2s nd,i 2s,s mx mx 2s 2s mx being the mximl for groth of the studied bcteri. Clculte the to prmeters: y s = j T 2(1-j,s,s ) + j,s,s ) + j,s,s ) nd, y i = j T 2(1-j,i,i ) + j,i,i ) + j,i,i ) Then clculte: Dj = j,s +j,s -j,i -j,i nd Dy = y s -y i The physico-chemicl inter-btch vribility of the food hs relevnt impct on the groth of the studied strin if t lest one of the prmeters Dj or Dy is over.2.