Table 2.
Complete overview of the designed model including the description of the dependent variables and the model equations
| Calculation | Description | Dependent variable | Model equation | ||
|---|---|---|---|---|---|
|
Subscenario 1. Cross‐contamination of bread |
1. A. Probability of one CFU being transferred from raw chicken meat to bread | 1.1. Probability of one CFU being transferred from raw chicken meat to bread (pC_B) (via hands, cutting board, and knife) | pC_B | Eq. 1 | pC_B = (tC_H * tH_B) + (tC_CB * tCB_CB * tCB_B) + (tC_K * tK_B) |
| 1.2. Probability of one CFU being transferred from raw chicken meat to bread (pC_B_p) (via hands, cutting board and knife), including type of handling into account. | pC_B_p | Eq. 2 | pC_B_p = ((tC_H * tH_B) + (((tC_CB * pCB) + (tC_CB * tCB_CB * pRCB)) * tCB_B) + (tC_K * tK_B)) * pCF | ||
| 1.3. Probability of one CFU being transferred from raw chicken meat to bread (via hands, cutting board, and knife), including the prevalence of MRSA at retail in raw chicken meat. | PC_B | Eq. 3 | PC_B = (pC_B_p * P_C) | ||
| 1. B. Number of cells transferred from raw chicken meat to bread | 1.4. Number of CFU being transferred per cm2 to bread from contaminated hands (N_H), cutting board (N_CB), rinsed cutting board (N_RCB), and knife (N_K). | N_H | Eq. 4 | N_H = binom (N_C, (tC_H * tH_B)) | |
| N_CB | Eq. 5 | N_CB = binom (N_C, (tC_CB * tCB_B)) | |||
| N_RCB | Eq. 6 | N_RCB = binom (N_CB, (tCB_CB)) | |||
| N_K | Eq. 7 | N_K = binom (N_C, (tC_K * tK_B)) | |||
| 1.5. Number of CFU being transferred per portion of bread (N_B) from contaminated hands (N_Hs), cutting board (N_CBs), rinsed cutting board (N_RCBs), and knife (N_Ks), considering the surface of the bread in contact with hands (SB_H), cutting board (SB_CB), rinsed cutting board (SB_RCB), and knife (SB_K) during food preparation. | N_B | Eq. 8 | N_B = (N_Hs + ( N_CBs *pCB) + ( N_RCBs *pRCB) + N_Ks ) * pCF | ||
| N_Hs | Eq. 9 | N_Hs = N_H * SB_H | |||
| N_CBs | Eq. 10 | N_CBs = N_CB * SB_CB | |||
| N_RCBs | Eq. 11 | N_RCBs = N_RCB * SB_CB | |||
| N_Ks | Eq. 12 | N_Ks = N_K * SB_K | |||
| Subscenario 2. Recontamination of grilled chicken | 2. A. Probability of one cell being transferred from raw chicken meat to grilled chicken | 2.1. Probability of one CFU being transferred from raw chicken meat to grilled chicken (pC_GC) considering the chicken meat at 90°C (pC_C90) and 60°C (pC_C60), via dish and barbecue tong. | pC_GC | Eq. 13 | pC_GC = ( pC_C90 + pC_C60 ) |
| pC_C90 | Eq. 14 | pC_C90 = (tC_D * tD_D * tD_C90) + (tC_T * tT_C90) | |||
| pC_C60 | Eq. 15 | pC_C60 = (tC_D * tD_D * tD_C60) + (tC_T * tT_C60) | |||
| 2.2. Probability of one CFU being transferred from raw chicken meat to grilled chicken (pC_GC_p) (via dish and barbecue tong), including type of handling into account and considering the chicken meat at 90°C (pC_C90_p) and 60°C (pC_C60_p). | pC_GC_p | Eq. 16 | pC_GC_p = ((pC_C90_p * pC90) + (pC_C60_p * pC60)) * pMF | ||
| pC_C90_p | Eq. 17 | pC_C90_p = (((tC_D * pD) + (tC_D * tD_D * pRD)) * tD_C90) + (tC_T * tT_C90) | |||
| pC_C60_p | Eq. 18 | pC_C60_p = (((tC_D * pD) + (tC_D * tD_D * pRD)) * tD_C60) + (tC_T * tT_C60) | |||
| 2.3. Probability of one CFU being transferred from raw chicken meat to grilled chicken (PC_GC) (via dish and barbecue tong), including the prevalence of MRSA at retail in raw chicken meat. | PC_GC | Eq. 19 | PC_GC = (pC_GC_p * P_C) | ||
| 2B. Number of cells transferred from raw chicken meat to grilled chicken | 2.4. Number of CFU being transferred per cm2 to grilled chicken (90°C and 60°C) from contaminated dish (NC_D), rinsed dish (NC_RD), and barbecue tong (NC_T_up, NC_T_down). | NC90_D | Eq. 20 | NC90_D = binom((N_C − N_CB), (tC_D * tD_C90)) | |
| NC90_RD | Eq. 21 | NC90_RD = binom( (NC90_D, tD_D) | |||
|
NC90_T_up NC90_T_down |
Eq. 22 | NC90_T_up = binom ((N_C − N_H), (tC_T * tT_C90)) | |||
| Eq. 23 | NC90_T_down = binom ((N_C − (N_CB + NC90_D)), (tC_T * tT_C90)) | ||||
| NC60_D | Eq. 24 | NC60_D = binom( (N_C − N_CB), (tC_D * tD_C60)) | |||
| NC60_RD | Eq. 25 | NC60_RD = binom( (NC60_D, tD_D) | |||
|
NC60_T_up NC60_T_down |
Eq. 26 | NC60_T_up = binom ((N_C − N_H), (tC_T * tT_C60)) | |||
| Eq. 27 | NC60_T_down = binom ((N_C − (N_CB + NC60_D)), (tC_T * tT_C60)) | ||||
| N_GC | Eq. 28 | N_GC = (( N_C90s * pC90) + ( N_C60s * pC60)) * pMF | |||
| N_C90s | Eq. 29 | N_C90s = ( NC90_Ds * pD) + ( NC90_RDs * pRD) + NC90_Ts_up + NC90_Ts_down | |||
| 2.5. Number of CFU being transferred per portion of grilled chicken (N_GC) (considering the hot grilled chicken (N_C90s) and the cooled grilled chicken (N_C60s)) from contaminated dish (NC_Ds), rinsed dish (NC_RDs), barbecue tong (NC_Ts_up, NC_Ts_down), including the surface of the grilled chicken in contact with the dish and rinsed dish (SGC_D) and barbecue tong (SGC_T_up, SGC_T_down) during food preparation. | NC90_Ds | Eq. 30 | NC90_Ds = NC90_D * SGC_D | ||
| NC90_RDs | Eq. 31 | NC90_RDs = NC90_RD * SGC_D | |||
| NC90_Ts_up | Eq. 32 | NC90_Ts_up = NC90_T_up *SGC_T | |||
| NC90_Ts_down | Eq. 33 | NC90_Ts_down = NC90_T_down * SGC_T | |||
| N_C60s | Eq. 34 | N_C60s = ( NC60_Ds * pD) + ( NC60_RDs * pRD) + NC60_Ts_up + NC60_Ts_down | |||
| NC60_Ds | Eq. 35 | NC60_Ds = NC60_D * SGC_D | |||
| NC60_RDs | Eq. 36 | NC60_RDs = NC60_RD * SGC_D | |||
| NC60_Ts_up | Eq. 37 | NC60_Ts_up = NC60_T_up * SGC_T | |||
| NC60_Ts_down | Eq. 38 | NC60_Ts_down = NC60_T _down * SGC_T | |||
| Subscenario 3. Consumer exposure | 3A. Probability of one cell being transferred from raw chicken meat to the final serving | 3.1. Probability of one CFU being transferred from raw chicken meat to the final serving considering the prevalence of MRSA at retail in raw chicken meat. | P_Ex | Eq. 39 | P_E = pC_B_p * pC_GC_p * P_C |
| 3B. Number of cells transferred from raw chicken meat to the final serving | 3.2. Number of CFU being transferred from the contaminated raw chicken meat to the final serving consisting in a slice of bread and in a piece of grilled chicken. | N_Ex | Eq. 40 | N_Ex = N_B + N_GC |
Abbreviations: tX_Y, transfer coefficient from X to Y; tX_X, persistence coefficient in X; N_X, number of bacteria in X; P_X, prevalence/probability of bacteria in X; C, raw chicken meat; H, hands; D, dish; B, bread; CB, cutting board; K, knife; T, barbecue tong; C90, grilled chicken at 90°C; C60, grilled chicken at 60°C; pCF, probability of cutting the raw chicken first; pMF, probability that the raw chicken meat is manipulated first; pRCB, probability of rinsing the cutting board; pRD, probability of rinsing the dish; pC90, probability that the grilled chicken remains warm at 90°C; pC60, probability of the grilled chicken to cool down to 60°C. The values of the parameters highlighted in bold have been calculated with specific equations.