key: cord-1053983-6l9q8b4y
authors: Ovca, Andrej; Škufca, Tina; Jevšnik, Mojca
title: Temperatures and storage conditions in domestic refrigerators - Slovenian scenario
date: 2020-10-19
journal: Food Control
DOI: 10.1016/j.foodcont.2020.107715
sha: b882a486c6dcb09b3e18b69b7e833e17fe12fa9e
doc_id: 1053983
cord_uid: 6l9q8b4y

Cold chain maintaining is least stable at its end, where domestic storage often represents one of the most critical links because of storage time and inappropriate temperatures, increasing the risk of food-borne outbreaks in domestic households. Considering the timetemperature profile of refrigerators as a food safety indicator, the purpose of this study is to gain insight into refrigeration temperatures in parallel with refrigerator and household characteristics that could potentially influence the refrigeration temperatures. During a 24 h period in 15-min intervals, internal temperature of the test product, refrigerator air and ambient air temperatures were measured with one penetration and two air probes coupled with a data logger. The internal temperature of the test product was measured with pre-prepared “Karlsruhe Test Material”, which had thermal properties similar to those of lean beef. Refrigerator and household characteristics were collected with a predefined observational sheet and short, structured questionnaire. In total, 50 households and their refrigerators were included. Gaps related to the cold storage and cross-contamination were observed. Temperature displays were present in 16% while control thermometers were not observed at all; 20% of the refrigerators enabled 24 h average internal temperature lower than 4 °C, 30% between 4 and 6 °C and 50% over 6 °C. Refrigerator age, type and load were observed but had no significant impact, which suggests thermostat setting as a key factor influencing refrigerator temperatures. Food distribution inside refrigerators was related to the refrigerator load with significant risk for cross-contamination in overpacked refrigerators. High temperatures combined with a non-systematic distribution of food in the refrigerator, expired dates of durability, and non-systematic cleaning strategies allow favourable preconditions for food infections occurring at the end of the food supply chain. Tailored acceleration of existing food safety messages could and should help consumers to minimise food safety risks, improve food quality, and reduce food wastage.

(Jevšnik et al., 2013), are operating above the recommended temperatures and support 25 suboptimum but still significant growth of mesophilic organisms, such as Salmonella spp. 26 Food safety and the quality of refrigerated food depend on the good performance of 27 the refrigerator and are closely linked to temperature distribution and airflow inside the visit, the researcher first explained to the responsible household member the planned 73 activities and what information would be provided afterwards as feedback. After an 74 explanation of all activities, the responsible household member was asked once again 75 regarding consent and, if they agreed, the researcher asked for access to the refrigerator. If 76 there was more than one refrigerator, the responsible household member was asked to 77 provide access to the main refrigerator used by household members. After the 78 measurements, the responsible household member was informed about the status of their 79 refrigerator and received oral recommendations from the researcher for the improvements 80 in refrigerator temperature settings and / or storage conditions. However, participants were 81 also informed about the possibility of refusing participation or changing their mind at any 82 time during the measurements, without any consequences. All the data were collected with 83 consent. 84 85 2.1 Temperature measurements 86 The internal temperature of the test product (ITTP) was measured in the pre-87 prepared "Karlsruhe Test Material" with a weight of 254 g. Karlsruhe Test Material, 88 previously validated by Anderson and Singh (2005) (Creswell, 2007) . The number of household members and demographic data (area of residence, 122 gender, age, education) about the household person who mostly buys food were gathered 123 with the help of a short structured questionnaire developed by the authors for this research. 124 After a prior explanation by the researcher, the members of the household, recorded their 125 activity every time they opened the refrigerator door during the measurement period on the 126 separate pre-prepared record sheet. The overall arithmetic means of ITTP, RAT and AAT mean temperatures were 5.95°C (SD = 141 2.24), 5.91°C (SD = 2.23) and 21.21°C (SD = 2.34) respectively. 20% of the refrigerators 142 enabled average ITTP lower than 4°C, 30% between 4 and 6°C and 50% over 6°C (Tab. 1). 143 Detailed analysis of RAT 24-h measurement profiles showed that only 4% of refrigerators 144 J o u r n a l P r e -p r o o f were operating below 4.0°C, while 24% of refrigerators were above 6.0°C during the entire 145 monitoring period. However, a detailed view on ITTP 24-h measurement profiles revealed 146 that in 10% of refrigerators the test product was kept at a temperature below 4.0°C during 147 the entire monitoring period, while in 38% of the refrigerators, it was above 6.0°C. 148 The three time-temperature profiles of refrigerators presented in Fig. 1 Fig. 1) . Similarly, ITTP and RAT thermal 152 change with cyclic pattern was typical for 86% of all measurements. Among the rest, an 153 atypical and less pronounced pattern was observed. Although a strong association between 154 average ITTP and RAT (r = .930, p < .001) was observed, a detailed view on 24h profile 155 revealed that RAT change rate during 24h was much more intense compared to ITTP (Fig. 1) . 156 In the case with the lowest average ITTP, the ON and OFF lapse time rate was much more in Overall, 34% of refrigerators were less or equal to 4 years old, 22% between 5 and 9 168 years, 28% between 10 and 14 years, and 16% more than 15 years old. Although the ratio 169 between newer and older refrigerators was in favour of the first related to average ITTP 170 (Tab. 1), there was no significant difference (p = .213) between average ITTP in newer (less 171 or equal to 9 years) refrigerators (5.6°C, SD = 2.1) compared to refrigerators older than 10 172 years (6.4°C, SD = 2.4). A similar situation was observed for RAT. 90% of all refrigerators had 173 solid glass shelves. 22% were equipped with a fan, more often newer refrigerators (p = .014). 174 Although average ITTP was lower inside the refrigerators with a fan (5.4°C, SD = 2.0) 175 compared to those without (6.1°C, SD = 2.3) the difference was not significant (p = .379). 176 Only a few (16.0%) of the refrigerators were equipped with temperature displays, while 177 none was equipped with a control thermometer inside the refrigerator. 178 The most common type of refrigerator observed in our study was one without a 179 freezer compartment (46%) followed by a double-door refrigerator combined with a freezer Only in three (6%) refrigerators were materials of wire shelves surfaces not completely 216 intact, but this did not represent a significant health risk. The average number of household members was 3.0 (SD = 1.2) in rural and 2.8 (SD = 220 1.2) in urban (p = .487) areas. Among household members who mostly buy the food, 74% 221 were women, 48% were above 50 years old, and 42% had completed higher or tertiary 222 education. Although household members who mostly buy food were on average younger 223 and more highly educated in urban area, there was no significant difference between both 224 sub-samples considering age (p = .258) and education status (p = .152). 225 The average ITTP was lower in households with women (5.6°C, SD=2.2) than in 226 households where men (6.9, SD=2.2) were responsible as the person who mostly buys food refrigerators without a freezer compartment were most frequently present in our study. 311 Also, the lowest average ITTP was measured among these types of refrigerators, which 312 might be related more to the fact that this type was the most abundant among refrigerators 313 with an age of less or equal to four years. previously by Ovca and Jevšnik (2009a) . They also reported that consumers buy high-risk 334 food items (e.g., fresh meat) mostly for daily use, which could also explain the absence of 335 high-risk food items in refrigerators of the current study. 336 Although pre-packed food items are labelled with durability dates (in addition to 337 required storage temperature), we determined that expired durability date was not related 

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• Gaps related to the cold storage and cross-contamination were observed • One third of refrigerators provided recommended temperatures • Temperature displays present in 16% while control thermometers not observed at all