The Effect of Storage Time in Influencing Pb Metal Content in Canned Food: A Review

The usage of cans as processed food packaging may cause toxicity in the form of metal contamination that is dangerous for the human body. Although canned food products spread in Indonesia have met SNI standards, metal contamination can occur or increase if the handling process is carried out incorrectly. The handling process of canned food that does not follow the standards made by Codex CAC/RCP 60-2005 on temperature exposure, storage time, and physical condition of cans is a factor influencing Pb metal contamination of canned food. Therefore, this study aims to summarize the effect of temperature exposure, length of storage, and physical damage of cans on Pb content in canned food. PRISMA guidelines were used as the method to find suitable sources for this systematic review. Relevant studies that were used are retrieved from several databases such as Science Direct, EBSCOhost, Taylor & Francis, and Wiley Online. The keywords used to identify the relevant studies were “metal contamination”, “heavy metal contamination”, “metal toxicity”, and “canned food”. The initial search in databases yielded 73 articles. After the screening process based on the criteria of the article, only 11 articles were used in the final systematic review. The result showed that storage time is most commonly related to the cause of increased Pb content in canned food compared to temperature exposure and physical condition. Therefore, the market must ensure that the handling process of canned food is carried out following Codex CAC/RCP 60-2005 to reduce the chance of increased Pb content in canned food products.


Introduction
Over time, the development of food packaging continues to progress to be more innovative and profitable.One of the food packaging that is currently used in the food industry is cans.Cans are commonly used for processed foods with high-water content, such as fruit or meat.Despite its many benefits, its use could cause toxicity to the human body in the form of metal contamination.In 2015, metal contamination in food caused more than 1 million cases of illness, 53,000 deaths, and 9 million cases of disability [1].The most common way metal contamination causes disease in the human body is through consuming foods with excess metal content.Food may contain metals through the migration of heavy metals from cans to food.Although there are safety standards regarding the metal content of food products, they may increase during the post-production process.While the quality of the company's products is guaranteed through the Quality Control (QC) and Quality Assurance (QA) departments, metal content can increase during the handling process carried out by modern and traditional markets.The handling process of canned food must be implemented according to the standards determined, namely the Code of Practice for the Prevention and Reduction of Inorganic Tin Contamination in Canned Foods (CAC/RCP 60-2005).The standard regulates temperature exposure, storage length, and the product's physical conditions that must be applied by modern and traditional markets [2].Incorrect temperature exposure, storage length, and the product's physical condition can increase the rate of heavy metal migration from the can into the food.
The factors of temperature exposure, storage length, and physical damage of cans are things that need to be considered to avoid increasing the content of heavy metals in canned food products.If these factors are not considered during the handling process, the transfer of heavy metals from cans can occur very quickly.Research by Moussawi et al. [3] showed that there was a drastic increase in Fe and Sn content when exposed to a temperature of 40°C.High temperatures lead to cans' corrosion, causing heavy metals to dissolve into food products.Perdana [4] conducted a study that showed an increase in Pb and Sn content in canned fruit juice due to long storage time.Storage time shows the contact time between the sample and the can.The longer the contact time between the sample and the can, the more migration of metals from the can to the food will be bigger.Besides Perdana [4], Aberoumand and Baesi [5] examined the effect of storage time on the Fe, Zn, Cu, and Hg content of canned tuna fillets.The longer the storage time, the Fe content will decrease, the Zn content will slightly increase and then decrease drastically, and the Cu and Hg content will show a drastic increase.According to Verissimo [6], the Fe content in fruit juice drinks using dented cans is much higher than in non-dented cans.The dent in the can damages the protective layer of the can, causing direct contact between the heavy metal and the product.
Previous studies have shown that exposure to temperature, storage time, and physical damage can significantly influence the metal contamination of canned food.Based on a scientific article by Moussawi et al. [3], the temperature that increases the corrosion of cans and the metal content of canned products is 10°C to 55°C.The limitation of Moussawi et al. research is unable to show the effect of temperature on Pb metal contamination in canned fruit.Perdana [4] showed the effect of storage time on Pb content in canned fruit.The limitation of the research conducted by Perdana is that there is no analysis of the effect of temperature and canned damage on Pb content.Aberoumand and Baesi [5] showed the effect of storage time on the content of Fe, Zn, Cu, Hg.The limitation of Aberoumand and Baesi's research is that there is no analysis of the effect of storage time on Pb content.Verissimo [6] compared the Fe content of canned fruit juice dented with those not dented.The results showed that the Fe content of canned fruit juice dented was higher than those not dented.Research conducted by Verissimo has limitations in not discussing the effect of dented cans on Pb content.
The previous research has identified the effects of various factors, such as temperature exposure, storage time, and physical damage on the increase of metal contamination in canned food.These influencing factors need to be avoided by modern and traditional markets to ensure consumer safety.The effect of temperature exposure, storage duration, and physical damage on metal contamination in canned food has been regulated by an internationally accepted standard, The Codex Alimentarius Commission.The Codex Alimentarius Commission established by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO), has developed several codes of practice to help ensure the safety and quality of food.CAC/RCP 60-2005 or Code of Practice for the Prevention and Reduction of Inorganic Tin Contamination in Canned Food is one such code that provides specific guidance on how to prevent metal contamination in canned food.This code offers valuable insights and instructions on how to protect canned food products from metal contamination caused by high temperatures, prolonged storage periods, and physical damage.By adhering to these guidelines, modern and traditional markets can ensure that their handling processes align with international standards and effectively minimize the risk of metal contamination.
Metal contamination in canned food products is highly dangerous to cause serious illness and death.Proper handling process procedures need to be considered to avoid metal contamination in canned food stored in modern and traditional markets.Handling process factors that affect the metal contamination content of canned food are temperature exposure, storage time, and the physical condition of cans.These influence factors have different results depending on the metal.The previous study only discusses the influence of temperature, storage time, and physical damage of cans on certain metals.There is no study summarizes the effect of temperature exposure, storage time, and physical damage on Pb metal contamination in canned food.Therefore, this study aims to summarize the effect of temperature exposure, length of storage, and physical damage of cans on Pb content in canned food.It aims to determine the influence of factors that need to be avoided and maintained on Pb metal contamination in canned food sold in modern and traditional markets.

Methods
The data search process follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol as shown in Fig. 1.The databases use published studies from Science Direct, EBSCOhost, Taylor & Francis, and Wiley Online.The keywords are "metal contamination", "heavy metal contamination", "metal toxicity", "canned food", kontaminasi logam, kandungan logam, and makanan kaleng.The data sample will be selected based on the characteristics of canned meat, canned fish, and canned fruit from modern and traditional market.The source will also be selected based on the characteristics of written in Indonesian, written in English, published in Indonesian or International journals, research articles, or journals made maximum in 2013.The sources found will be screened based on objective sources related to this research objectives article.Then, some information will be extracted, including exposure to temperature, storage time, dented cans, samples from modern or traditional markets, and Pb content.

Results of the Effect of Temperature Exposure on Pb Content
Observations on the effect of storage temperature on the increase of Pb content were conducted by Kassouf et al.Using canned chickpeas samples purchased in Lebanese markets and stored at cold temperature (5 o C), room temperature (22 o C), and oven temperature (40 o C).The Pb content was checked on days 0, 30, 60, and 90 [7].
Samples exposed at room temperature (22 o C) had Pb levels that grew higher every day of checking.On day 30, the Pb level in the sample exposed to room temperature was 0.1 µg/g; on day 60, it was 0.25 µg/g; and on day 90, it was 0.6 µg/g.Samples exposed to low temperature (5 o C) experienced an increase in Pb levels on day 30 (0.1 µg/g), then decreased on day 60 (0.08 µg/g), then increased again on day 90 (0.18 µg/g).Samples exposed to hot temperatures (40 o C) have not experienced an increase in Pb levels on day 30, Pb levels in the sample are still the same as on day 0. The increase began to occur on day 60, Pb levels increased from 0.05 µg/g to 0.12 µg/g.Then, a drastic increase occurred on day 90, Pb levels from 0.12 µg/g increased to 0.6 µg/g.Kassouf et al. concluded that Pb levels in the sample will increase dramatically when exposed to temperatures of 22 o C-40 o C. Cold temperatures (5 o C) still increase Pb levels but do not occur as fast as samples exposed to high temperatures [7].

Results of the Effect of Physical Condition on Pb Content
The effect of physical condition on Pb content in canned food was observed by Kassouf et al.Samples of dented and undented cans have the same production date and storage conditions.Kassouf et al. found that Pb levels in dented cans were 38% higher than in cans with good physical conditions [7].
Dents in cans will cause deterioration of the tinplate layers in the can.It can cause corrosion and release of metals into the product.Moussawi et al. showed that dents in cans increased Fe content by 20%, Sn content by 44%, and Cd by 94% [3].Pb metal that was not detected in the observations made by Moussawi et al. was due to the metal constituent of the cans in the sample not containing Pb.If the cans used contain Pb metal, the Pb will also be released and move into the food if the tinplate layer on the can is damaged due to dents.There is a difference in lead levels at each storage period.The longer the shelf life of canned fish, the more lead it contains [8].
Observations made by Refilda et al. using canned fish samples with a storage period of 6 months, 18 months, and 36 months.The lead level in canned fish samples with a shelf life of 6 months was 0.387 mg/L, a shelf life of 18 months was 0.512 mg/L, and a shelf life of 36 months was 0.807 mg/L.Based on the observed lead level data, canned fish with a longer storage period had higher lead levels [9].
The observations made by Syakri and Mursyid used canned meat "x" and canned meat "y" samples stored in the refrigerator for one day.The data found was a decrease in lead levels in canned meat sample "x" and an increase in lead levels in canned meat sample "y".The canned meat "x" sample, before being stored in the refrigerator for one day, had a lead level of 0.258 μg/g, then decreased in lead level after being stored for one day to 0.228 μg/g.The canned meat sample "y" before being stored in the refrigerator for one day, had a lead level of 0.182 μg/g, then increased the lead level after being stored for one day to 0.453 μg/g.There are different results on the effect of storage time on canned meat samples "x" and "y", therefore the results of the research conducted by Syakri and Mursyid cannot be identified regarding the effect of storage time on lead levels in canned meat samples [10].Observations made by Karlina et al. using canned fish samples with storage durations of 5 months, 9 months, 19 months, 27 months, and 33 months.From this research, lead levels were not found in all observation samples.Lead levels in canned fish samples with a storage period of 5 months, 9 months, 19 months, 27 months, and 33 months were not detected.This is because the cans used as packaging in the canned fish samples observed by Karlina et al. did not use lead metal during the can-making process, processing, or connection process [11].

Conclusions
Lead is a metal that is often found in cans and may migrate into food.The effects of lead exposure on the human body are very harmful to all organs, especially the nervous system.Factors that are often observed in influencing the increase of metal contamination in canned food are storage time.This is because storage time equals the time that leads to contact food.However, research on the effect of temperature exposure, physical conditions, and storage time on the increase of lead content needs to be explored further to find the best handling process for canned food to fulfill the Sustainable Development Goals (SDGs).Point 2 (Zero Hunger) and point 3 (Good Health and Well-Being) can be achieved by finding the best handling process (temperature exposure, physical conditions, and storage time) that can prevent human health risks caused by metal contamination.
Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol.

Figure 1 .
Figure 1.PRISMA Flowchart . Result of The Effect of Temperature Exposure on Pb Content

Table 2 .
Result of The Effect of Physical Condition on Pb Content Results of the Effect of Storage time on Pb Content Some research has analyzed storage time factors affecting Pb content in canned food.Observations made by Erfandika et al. using canned fish samples with a storage period of 1 month, 6 months, 12 months, 18 months, and 24 months.
. Result of The Effect of Storage Time on Pb Content