Food Safety Risks in Flour and Hygiene and Sanitation in Flour Mills for Producing Safe Flour
05 August 201322 min reading
Doç. Dr. Mustafa ERBAŞ, Sultan ARSLAN, A. Nur DURAK
Akdeniz University Faculty of Engineering Department of Food Engineering, Antalya
It is a fact that one of the basic conditions of ensuring the food safety at high levels is supplying low-risk raw materials. Producing the flour and flour products in accordance with food safety begins with obtaining safe wheat.
Wheat flour is described in the Turkish Food Codex Wheat Flour Notification (2013/9) as the flour obtained by milling the wheat in parallel with the technique of being purified from inorganic substances like sand, soil, stone and metal and organic substances like animal, plant and insect residues in hygienic conditions; that does not include strange taste, smell and substance and having its own unique color and appearance. It is stated in the notification that the flour should be produced in accordance with food safety.
It is a fact that one of the basic conditions of ensuring the food safety at high levels is supplying low-risk raw materials. Producing the flour and flour products in accordance with food safety begins with obtaining safe wheat. Thus, as well as flour industrialist has the main responsibility for providing flour safety; the farmers producing the wheat, the persons carrying out the harvest and transportation operations and traders should also apply hygiene and sanitation rules in their operations.
As the absolute right of the consumers, food safety is a concept expressed as set of measures that should be taken at each stage from production to consumption for making the food products not constituting health problems for humans. In order to achieve the flour safety from the field to the table; the wheat should be grown by good agricultural practices (GAP) and milled by good manufacturing practices (GMP) and good hygiene practices (GHD).
Food safety is handled as a set of systems in the Food Safety Managing System (TS EN ISO 22000) which is an international standard. With this standard it is aimed to establish a system based on hygiene and sanitation in the food businesses for ensuring the food safety at the highest level via the methods like forming interactive communication, system management and pre-requisite programs; reducing crop losses and costs and using HACCP (hazard analysis critical control point) plans.
Food hygiene is providing the conditions necessary for keeping all threats and risks that can cause health problems under control and preventing the consumer from any disease through food products. Sanitation is described as making the cleaning operations necessary for purifying the environment from disease-causing factors systematically.
Food safety of the flour in wheat storing and milling businesses should be ensured by using TS EN ISO 22000 food safety, ISO 9000 quality and ISO 14000 environment management standards integrally. Applied food safety and quality systems should ensure the cleanliness, hygiene and quality expectations.
The flour industry has the low food safety perception because of the reasons like that water content of the flour is low; it is not a product ready for consumption directly and baking operation is applied to the flour products before the consumption. While the unsafe food creates health risks, they cause loss of money, time and reputation and legal problems, as well. The main responsibility of ensuring food safety primarily belongs to the food business operator. It should be kept in mind that besides food safety, establishing food safety systems in a flour mill also provides economic benefits.
The amount of contaminants and pesticides in the flour and its microbiological condition should be in accordance with the provisions of Contaminants, Maximum Residue Limits of Pesticides, Microbiological Criteria and Food Hygiene Regulations of Turkish Food Codex published on the official gazette dated as 29.12.2011 and with third repeated number 28157.
Likewise, the food hygiene condition should be in accordance with the provisions of “Food Hygiene” regulations of Turkish Food Codex published on the official gazette dated as 17.12.2011 and numbered as 28145. In this study it is aimed to explain the factors that disrupt the food safety of the flour and the effects of these factors on public health; indicate the critical points that can be effective on ensuring the flour safety and introduce the measures that can be taken.
DETERIORATION WAYS OF FLOUR SAFETY
The factors that form food safety risk in flour production are intertwined and can be basically classified as physical, biological and chemical.
1. Physical Risks
The physical risks mostly coming with the wheat consist of animal and vegetable organic substances like stalks, straw, food waste, gum, cigarette butts, weed seeds, rodent hairs, insect parts, feces, etc. and inorganic substances like stone, soil, sand, metal and glass. All organic and inorganic substances should be separated from the wheat well before the storing and milling operations because of both the risks in their chemical components and the microbial loads they carry. As the inorganic impurities cause disruption of the integrity of grain and the grains not matured enough include high grain water content, they both can become the source of mold infections.
2. Biological Risks
The most important biological risks endangering flour safety are microorganisms and pests. Grains are really open to the microorganism and pest contamination due to production, harvesting and transport conditions. There is an important amount of bacteria, yeast and mold load on the grains because of these contaminations. Molds create more important risks on flour safety compared to bacteria and yeasts as they can breed in low water activity and heat conditions due to their physiologies and form dangerous mycotoxins with high heat resistance
- Mold and bacteria
Mold growth depends on environmental factors like heat, relative humidity and oxygen content and the water content of wheat kernel. Mold activity increases together with the heat increase after the kernel water exceeds 14 % value that is the critical water content and the relative humidity of the environment exceeds 65 % that is the critical relative humidity rate. Starting in the regions with high water content firstly, the mold activity creates important threats on wheat and flour safety by continuing to grow in the kernels which lose their mechanical integrity and in the embryo parts of the kernels.
The molds can contaminate mostly to the species of Aspergillus spp., Penicillum spp., Fusarium spp. and Alternaria spp. types of grain. The mold types of these species can create important threats on flour safety as they produce dangerous toxic metabolites called mycotoxins such as aflatoxin, ochratoxin, zearalenone, patulin, deoxynivalenol, trichothecene and fumonisin.
These mycotoxins that do not decay during the baking process cause various damages on the vital systems of human and animals and also cancer. As a mycotoxin produced by Aspergillus mold that can grow fast on the grains like wheat, aflatoxin is defined as a first-degree carcinogen by International Agency for Research on Cancer (IARC). Being in an alkaloid structure and produced by Claviceps purpurea (ergot of rye, ergot mold) mold, lysergic acid causes a serious and malignant disease called as ergotism (Antony fever).
In some instances the moldy grains deteriorated because of bad storage, can be put in the market by being processed after some operations like washing. As a result of this, an extremely dangerous situation and exposure come out as these products contain carcinogenic mycotoxins such as aflatoxin and ochratoxin and grain based products are widely consumed by the entire community. People are not even aware of this situation.
Mold growth can be seen at uncontrolled points of some parts where the washing and annealing units inside the flour mill and at some points where vapor is intensified inside the closed systems. This vapor is formed by the separation of water from the product inside the equipment like roller, screen and purifier. These molds can cause health problems for the consumer because of both themselves and the mycotoxins they produce by mixing with the flour in time.
While molds can grow at 25-30°C, some of them can also grow at heats low to 0°C and high to 55°C. Molds can breed fast in the food products that are rich in carbohydrate and lipid like cracked wheat whose physical integrity is deteriorated and with a pH value of 2-7.5. For the mold growth the relative humidity of the environment should be over 62 % and the material water content should be over 10 %.
As molds are aerobic livings, their growth fairly slows down in the environments with low oxygen (O2) or with carbon dioxide rate (CO2) higher than 12 %. It is detected in a study on gas composition of the storage and the formation of ochratoxin that ochratoxin production in an environment with a water activity value of 0.80 and CO2 level over 30 % completely stops. It is detected by another study that the toxin produced by Fusarium type of molds, is not formed in a storage environment with 50 % CO2 and 20 % O2.
As the environment heat and humidity conditions become more appropriate for yeast and bacteria activities after mold activities, these microorganisms cause more deterioration of the product and threat for the customer.
Salmonella spp., Escherichia coli, Bacillus cereus are common pathogen bacteria that threaten the food safety of flour. Using flour as the main element in the kitchen and mixing the flour and food that can also be consumed as raw intentionally or unintentionally can cause serious food poisonings occurred due to the flour containing pathogenic bacteria. Consuming Salmonella bacteria with food even in little amounts like 1 log cfu/g can cause serious diseases.
According to the results of a research completed in 2005 and realized on 4358 samples with average 14 % water content; total Mesophilic Aerobic Bacteria (TMAB) amount is determined as 4.41; Escherichia coli amount is 0.84; mold amount is 2.58 and yeast amount is 1.79 log cfu/g. according to the results of microbiological analysis made on 142 samples obtained from Turkish flour mills; it is determined that the amounts of TMAB, E. coli, Bacillus cereus, Clostridium perfringens, Salmonella spp, mold and rope-sports in some samples are over Turkish Food Codex.
Livings like insect, mite, rat and bird are called as pests. Known also as vertebrate pests, rats and birds threaten the flour safety seriously by contaminating the microorganism and parasites in their bodies and feces to the flour. As a result of these pest activities, various serious diseases like typhoid fever, paratyphoid fever and salmonellosis can develop.
While the rats that threaten the flour safety are split into three groups as Rattus norveginucus (Norway rat, brown rat), Rattus rattus (roof or ship rat, black rat) and Mus musculus (home rat); birds are defined as local bird species living in the business area. As an important risk element, bird residues and feces are known as the main contamination source for salmonella bacteria’s contamination to the flour which can cause serious food poisonings.
Because of their numbers and breeding speed insects and mites constitute the most important pest group that gives damages to the grains and threatens the flour safety. As a result of the activities of these pests; besides wheat loss in the storage, important health problems come out in the product, some problems on the technological processability and sensory properties of the product occur and flour safety is imperiled.
While the insect activity is scarcely any low in the approximately 10 % kernel water content and at 5°C, it can reach to the highest level in 13 % kernel water content and at 21°C. When the oxygen rate of the atmosphere inside the storage is lower than 2 % and/or the carbon dioxide rate is higher than 12 %, the insect and mite activities are minimized.
Pests such as Sitophilus granaries L. (weevil), S. oryzae L. (rice louse), S. zeamais (corn borer), Trogoderma granarium (Khapra beetle), Rhizopertha dominica F. (crop hump beetle), Tribolium confusum and T. castaneum (half-blood lice), Ptinus fur L. (white-spotted spider mite), Nemapogon granellus L. (crop warehouse moth), Ephestia kuehniella (mill moth), Acarus siro L. (flour mite) are the common insect and mite species that create important risks on flour safety.
Being milled together with the wheat or formation of these insects themselves and their body rash (larval sloughs, pupa coverings and body residues of deceased persons), feces and nets made by the larval of especially Lepidoptera insects in the flour can cause important quality losses in the flour and health problems of the consumer. Besides causing bad smells in the flour, mite feces cause health problems like allergic skin and lung diseases (asthma) for the consumer.
Wheat loses kernel integrity because of mechanical reasons by being split during harvest, transportation and transfer operations. Substrate and enzymes that are in separate parts of a substantial kernel can speed up the deterioration of the grains together with the loss of kernel integrity as a result of splitting. Especially the lipids cause the grains go bitter and deteriorate fast by being effected from the lipolytic enzymes even under the safe storage heat. The bitter wheat and flour show negative effects on consumer health because of the peroxides and free radicals they include. Besides, as the disintegrated kernels lose the protection of the husk, they form a good initial environment for the formation of insect and mold damage. Thus it is quite important to supply and store the wheat without splitting in terms of flour safety.
3. Chemical Risks
Chemical factors that threaten the flour safety consist of pesticides used in the fields, pesticides used in the businesses for insects and rodents, fumigation, hygiene and sanitation products, personal hygiene materials, metals, heavy metals, dyes, radioactivity, etc. Besides the mycotoxins formed by the molds, the chemicals in the insect feces and rash and the alkaloids of the weeds also risk the flour food safety.
In the event of that the wheat is milled for flour before the weed seeds like ryegrass (Lolium temulentum), corncockle (Agrostemma githago) and Syrian scabious (Cephalaria syriaca) are cleaned away completely; the toxic substances in these seeds may cause serious health problems for the consumer. The temulin alkaloid in the ryegrass seeds can create effects on the neural system of the livings that result with death.
CRITICAL CONTROL POINTS IN SAFE FLOUR PRODUCTION
Besides the quality analysis during wheat purchases to the business; other analysis that give an idea about food safety and intended for determining the risks like insect, mold and aflatoxine should be done. In order to provide food safety in the flour mills critical control points (CCP) should be determined pursuant to HACCP principles. Raw material procurement, storing, cleaned annealed wheat and flour packaging stages should be considered as critical points. Also, before the cleaning, milling and packaging processes both the flour safety and job security should be ensured by separating the metals from the products with a magnetic separator.
Wheat with excessive insect and mold load shouldn’t be taken into the business. The wheat with the values higher than Turkish Food Codex limit values, which are aflatoxine B1 content 2 µg/kg and total aflatoxine content (B1, B2, G1, G2) 4 µg/kg, shouldn’t be used in flour milling. The wheat storages of the business should be kept under control and intervention should be made in order to provide safe storage conditions as the increase of the kernel water content of the wheat over 14 %, storage relativity humidity over 65 % and the storage heat over 15 °C will promote the mold and pest growth. The purified annealed wheat should be checked before it is given to the first splitting roller; if there is an insect-mold contamination or growth, it should be sent back to the cleaning stage. The flour should be checked by re-screening at the packaging stage and any intake of foreign material inside the package should be prevented.
METHODS OF ENSURING FLOOR SAFETY
In order to get safe flour from a flour mill; firstly inputs like wheat, processes like cleaning, storing and milling and final products like flour should be defined by evaluating in terms of food safety. Firstly the condition of raw material and process and then the risks formed or contaminated during the processing stages should be determined. A set of methods can be used in order to prevent the deterioration ways of the flour safety explained above.
1. Sanitation and Cultural Methods
Firstly the construction style, choice of the machines and food safety conditions in the establishment should be taken into consideration. The business and the storages should be constructed as to be convenient for filling, evacuation, internal transport physically and cleaning and not to include dead points. The walls should have smooth surfaces and there shouldn’t be any flaking, swelling, exfoliation, recesses, projections and pits. The ceiling should be covered with smooth and impermeable material and the floor with solid, durable, vacuum concrete that doesn’t make powdering or epoxy material.
At least 1-meter clean and open area should be created in order to observe the transition of the pests between the building and its surrounding and the entire environment should be kept clean and well-groomed. The windows and doors that are kept open should be covered with lathes. The doors and windows at the lower floors should be made of metal in order to prevent the entry of rodents. The doors should be able to be fully closed with solid rubber and do not allow dust and pests and also do not have dead zones. The windows should have laths that can be demountable. The entrances of the building shouldn’t be lightened directly at nights.
The inside of the business should always be kept clean; scattering around of the flour and wheat should be prevented and the openings, cracks and dead areas that allow pest entrance and hiding should be closed. A flour mill has a daily, monthly and yearly cleaning and pest control plan. The content and process of this plan should always be updated according to the internal and external evaluations. Flour mills should also have a good dust collecting and discharge system. A flour mill whose inside and outside is clean, tidy and well-groomed should be evaluated as the basic condition of flour safety and quality.
Formation of uncontrolled wet area inside the business should be prevented and dripping taps should be repaired in order to prevent the pests to reach water. If the wheat is washed in the business, the water should have drinking water quality. The toilets should be arranged as one for each ten employees; the walls and floors of the toilets should be clearable and should have running water and personal care possibilities (soap, paper towel, drying machine, disinfectant) enough and also have a good cleaning scheme.
The sick wheat that is contaminated excessively with pest and mold, darkened, smells tarted mold and uric acid shouldn’t be taken into the business. The wheat to be taken into the business storage should be processed by a pre-cleaning system consisting of screening, aspiration and entolation. The first stored (FIFO- first in first out) wheat should be used in the usage of stored wheat.
As large and small materials are separated with screens, light materials with aspirators, stones with stone separators and weed seeds with trieur and the insect and insect eggs are destroyed by entolators, these systems should be provided at the cleaning line. Also as the husking and brushing processes decrease the dirt, number of microorganisms and amount of chemical contaminants, the systems realizing these processes should be used together with aspiration.
As the annealed wheat may be molded, it shouldn’t be waited too long for the milling. The flour should be re-screened by the flour screen both before transportation in bulk and the final packaging. All devices, especially the ones used flour in bulk transportation should be prepared pursuant to the hygiene and sanitation rules and the water vapor is prevented to form droplets by condensing.
For the addition of additives for special flour, the limits stated in the Turkish Food Codex should be taken into consideration. The substances that are not allowed in the food shouldn’t be used. Unnecessary materials shouldn’t be kept in the production area; pesticide (insect and rodent pesticides) that threatens the food safety, chemical substances used in cleaning and maintenance should be kept locked in a special storage by being grouped in terms of their species and features.
The business owners and employees should have basic hygiene and sanitation information; attach importance to personal hygiene and care; be well-intentioned, open to innovations and learning, care his/her health, inform the workplace when they are ill and understand the risks and costs of producing unsafe food. The staff should be ready in the working areas with the proper business attire; the visitors can enter the production areas with apron and galosh. Even if they are inoculated, pets shouldn’t be allowed in the production areas.
2. Physical Methods
Realization of the wheat and flour transportation inside the business as far as possible by the pneumatic systems working with air would provide separating the insects from the products at the cyclones because of the terminal speed difference and that these systems decrease the protected areas for insects.
The insect and their eggs can be destroyed and separated by using the entolation operations working with screening, aspiration and pulse technique integrally. In order to destroy the insects and the eggs without giving any harm to the wheat, the entoleter speed should be 1750 d/d inside wheat and 2900 d/d inside the flour. One of the most important methods for pest control is using trap. Covered or sticky traps can be used effectively for pest control by making the traps attractive with light or sex hormone effects.
Naturally the wheat is in contamination with many microorganisms. The microorganism content of flour decreases 90 % compared to wheat as a result of cleaning and husking operations and with the separation of bran and embryo that carry the microorganism load of wheat from the flour. Washing with water having drinking water quality also decreases the dirt on wheat and the recess on its belly and microorganism load significantly.
The insects that show propagation in the flour mills, are active at mostly average heats (15-25°C) and are really sensitive to very low (<0°C) or high heats (>50°). However low or high heat practices are the methods that should be applied very carefully as the flour and wheat have high heat isolation feature and the insects move a lot and fast.
It is really important to evacuate all the materials in the business and open and clean all the crowded spaces where all the machine and equipment are. The necessary measures should be taken before the implementation by considering the deformation to be formed in water pipes with cold applications and in plastic materials with hot applications.
Low heat application can be done with a very low cost in the regions where the temperature falls below zero by leaving the doors and windows open when the mill doesn’t operate after covering them by lathes for preventing bird entrances. Constituting a great part of insects showing propagation in the flour mills, flour lice (Tribolium spp) dies in 1-3 days at the temperature below zero.
With 49-55°C heat applications in the flour mills, most of the insects can be killed in 12 hours and the rest in 48 hours. With these heat conditions the eggs, larva and pupa of the insects can also be destroyed. Closing firmly the transitions between the floors and all doors and windows opening outside is quite important in the heat applications. In a research it is determined that energy cost of keeping the unit volume inside the mill at 50°C for 24-50 hours is 3-4 kWh/m3 depending on the climate and heat isolation conditions.
Forming medium temperature (20°C) areas trapped for pests in specific areas of the mill in order to increase the effectiveness of the both low and high heat applications and inciting the pests to go to those areas can increase the effectiveness of the application.
3. Chemical Methods
The most effective method to ensure food safety against pests is fumigation with phosphine (PH3) gas. Phosphine fumigation is preferred because of leaving little amount of residuals and ease of application. 650 ppm phosphine gas concentration of the storage atmosphere in the fumigation is determined as the optimum value for pest control. As the phosphine gas is oxidized into the phosphoric acid with the existence of light, it is more suitable to make the fumigation applications in the evening. Besides, as phosphine gas reaches high concentration (>%1.79) in the closed atmosphere, great attention is needed in terms of job security.
In the research results, it is determined that phosphine application is extremely effective in the modified atmosphere environment. In another research, it is determined that all pests and even resistant flour lice are killed easily within 15 hours of phosphine application when the environment temperature is 40°C and the atmosphere CO2 rate is over 70 % at a flour mill that is closed firmly and where impermeability is provided. Various chemicals like pesticide used commonly for pest control can cause serious health problems for consumers because of its residuals. With contact effect against insects, some chemical insecticides can be used but they are suggested at all. They should be used only when necessary by being careful about the application limits. Actually the hypercorrect is applying these chemicals with contact effect only to the pest transition areas without contaminating to the wheat.
4. Biological Methods
In the recent researches, some biological agents including enzyme, pathogen microorganism and parasites are developed. For example, the phytase enzyme application on insects causes direct death or death with infections by smashing the chitin-based integument of the insects. Besides the effects of some biological agents that disrupt the development of insects or spaying them are searched.
If the wheat and flour that is used widely in the nutrition of the society is not produced and stored in good conditions, mycotoxins especially formed by mold, pathogen microorganisms contaminated by pests and the parts of their bodies form serious threats on consumer health. In order to provide flour safety and protect community health; great importance should be given to staff training, the dead spaces should be closed, the equipment should be kept clean, scattering around of wheat and flour should be prevented and continuous monitoring and improvement for flour safety should be done.
Consequently; the basic principle of ensuring flour safety in the flour mills is applying a systematic approach including trained and well-intentioned staff, good production applications, feedback, traceability, inspection and enforcement.
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