Storage warehouse is a place to receive and store rice stocks, there are several procedures that exist in warehouse operations
Rice is one of the main food ingredients in our lives. Rice that is processed into rice as the food we consume every day is so dominant. However, rice storage itself is not so easy to implement because there are various risks in terms of physical, chemical, physiological, can cause biological changes. These change factors can cause the rice to be damaged or experience a change in taste.
According to James F. Thompson,good warehouse methodto prevent rice quality degradation is by:
1) Keep warehouse under 65% relative humidity, minimal mold growth is achievable under 65% relative humidity and minimal bacterial growth at higher relative humidity levels.
2) Keeping average monthly air temperature of 10 °F or -12°C <= x < 60 °F or 15.5°C for as long as possible throughout the year.
3) Design and operate an aeration system to maintain uniform humidity and temperature of rice.
4) Only store rice that has been cleaned properly so the unwanted defect doesn't spread to other rice.
Figure 1 Standard Rice Procurement Procedure
Image Source : D .Deviga, J. Vijayalakshmi & Rahman, A.(2016).Determination of Storage Loss in Rice with Respect to Moisture Loss in FCI. International Journal of Latest Trends in Engineering and Technology. ISSN : 2278-621X
Storage warehouse is a place to receive and store rice stcks, there are several procedures that exist in warehouse operations:
At this stage the supplier delivers rice to the warehouse according to the existing contract agreement. When the goods have arrived at the warehouse, the truck driver who delivers the rice will usually provide a delivery document letter to the warehouse purchasing department. The rice then unloaded and weighed by warehouse staff to determine the weight of incoming stock.
Warehouse staff shall do a screening check of the quality and condition of the incoming goods in terms of characteristics, if the rice received does not meet several standard, further treatment will be carried out or can be proceed to return policy to the supplier (depending on the each warehouse existing policy).
Several aspect must be paid attention into when assesing rice quality/characteristic :
Figure 2 Characteristic Quality Standard of Rice According to the Department of Food & Agriculture
Image Source : https://pertanian.pontianakkota.go.id/artikel/78-kelas-mutu-beras.html
a. Moisture Content Precentage
Rice should not have a moisture content above 14%, if the rice has more than that, it has to be further dried up until the water content meets the standard, which is in the range of 13-14% if the rice is too dry it will also break easily. Testing the level of water content can be done with tools such as
Figure 3 Grain Moisture Meter Comet CD6E
Image Source : https://www.pancaprimawijaya.com/read/index/id/53/shizuoka-seiki-comet-cd6e-grain-moisture-meter-made-in-japan.html
Testing the moisture content level can be done with tools above, but if the moisture content exceeds the standard but is still within the tolerance limit, drying can be done either manually or by the help of drying machine.
Rice that have been dried to a moisture content of 8-9% has to be quickly rehydrated (re-absorb water) mixed with boiling water. Rice will be quickly rehydrated if the rice have a smaller size and boiling water is added in the range of 190oF - 210oF (73.5-116.7oC) by soaking.
b. Degree of Whiteness of Rice
This measurement was carried out to determine the percentage of the detachment rate of the institution and the layer of the epidermis that coats the rice seeds. The higher the husk of the rice has completely removed and it affects the appearance of the whiter rice which is preferred by consumers.
Figure 4 Rice Milling Meter Trenocci TMD3E
Image Source : https://www.pancaprimawijaya.com/read/index/id/261/rice-milling-level-meter-trenocci-tmd3e.html
Measuring the degree of whiteness or the degree of shape can be done with a tool called a Milling Meter or Whiteness Meter with digital technology
c. Rice Head and Broken Rice
Figure 5 The Wholeness of Head Rice and Broken Rice Categorization based on SNI or Indonesian National Standard
Image Source :https://bbpadi.litbang.pertanian.go.id/index.php/info-berita/info-teknologi/aspek-mutu-beras
The quality of rice is also determined by the appearance and the wholeness of its shape and can be said to be good if it has a high percentage of wholeness rice and head rice reaching 75-80%. The separation between head rice and broken rice can be done with a sieving machine, Rice Mini Grader or it can also be done with a centrifugal machine.
Figure 6 Rice Mini Grader TRENOCCI TGM2A
Image Source :https://www.pancaprimawijaya.com/read/index/id/264/trenocci-tgm2a-laboratory-rice-grader.html
If quality control / assessment has been done then purchasing department will notify the supplier the quality condition of the goods and decision making regarding goods return policy shall be made and goods purchasing payment also be processed (depending on each company policy or managerial system but in general it works like that)
Rice that has gone through the quality sorting process will be entered into the packaging and re-weighing procedure so that data collection can then be carried out on finished rice stock items that are ready to be commercialized or stored for longer period of time. Rice stock can be assigned a different code based on the quality/grade (if there is such quality grade differentiation) and based on the supplier code to make it easier to evaluate the quality of the stock in the future.
Rice that has gone through the sorting or selection process will be stored as stock and entered into the finished goods stock book data collection, including data collection on the quality of the rice stock. After the storage process has been completed, periodic evaluations can be carried out in terms of checking water content, packaging conditions, warehouse conditions, rice quality, functionality performance of machines and warehouse utilities such as lighting and overall warehouse cleanliness and providing adequate fumigation.
The main risk of rice storage process is surely the rice quality defect itself or storage losswhich caused by many different factors such as :
1. Physical Factor
Physical is related to the temperature and humidity conditions of the storage warehouse, the criteria for poor rice storage warehouses can cause physical and chemical damage to rice and even inviting pests population.
The criteria for a good storage warehouse are having good relative humidity and no leaks on the roof or wall easily and then not having holes where insects can easily enter, besides that the warehouse building should not be made of flammable materials.
The humidity condition of the warehouse building should be maintained with a relative humidity control below 60% or 65%, besides that high warehouse temperatures can also trigger chemical reactions and cause unwanted changes. Warehouse cleanliness must always be considered and maintained by periodic cleaning.
2. Biochemical Factors
This factor is related to the water content and changes in the enzymatic reaction of rice, in general, the higher the temperature and water content, the more likely it is to grow mushrooms. These changes can result in a musty smell and a reduction in the smell of rice.
3. Physiological Factors
The natural characteristic of agricultural commodities including rice is that the metabolic process (respiration, transpiration) is still running even though it has been harvested. This process of respiration and transpiration produces CO2, H2O and energy (calories) until the material is damaged and the life processes stop.
H2O produced if it accumulates and is not handled or controlled properly will increase the moisture in rice which will trigger the growth of fungi. In rice seeds, the growth of microorganisms in stored rice will affect seed discoloration, and inhibit germination.
The accumulation of volatile gases such as acetaldehyde C2H4O, acetone C3H6O, methyl esters, valeraldehydeC5H10O., Hydrogen Sulfide H₂S and ammonia CH4 cause sour and musty odors, besides that these gas compounds are also flammable so that building materials are important to pay attention to.
4.Biological Factors
Figure 7 Insects Pest Rice Weevil Commonly Found in Rice Storage
Image Source :Pitaloka, Adelia L, dkk. 2012. Gambaran Beberapa Faktor Fisik Serangga Hama Gudang. Jurnal Kesehatan Masyarakat. 1(2) :217-218
According to (Halid, 1983: Haryadi, 2006), other damage to rice is caused by warehouse pests such as rats, mites, birds and the most frequent cause of the biggest damage is insects in the form of a decrease in the quality and quantity of the stored rice weight which leads to storage loss. Insects also have rapid reproduction and can spread so that they can invite the growth of molds / lice and fungi.
What is undesirable from insects / molds is secondary metabolism that produces mycotoxins. When mycotoxins are ingested together with food that has been contaminated with mycotoxin-producing contaminants, it can cause poisoning, which is called mycotoxicosis. The quality of food contaminated by mycotoxin-producing molds will decrease so that it is not suitable for consumption (Hastuti, 2010).
5.Packagingand Storage Process Factors
Packaging is intended to extend the shelf life of rice, maintain quality by protecting rice from external factors such as pollutants, rainy weather, humidity, microorganisms, oxygen O2 (because in the absence of oxygen, insects cannot live), and so on broken Packaging is an entry for insects to enter the rice so that monitoring of packaging condition is also important.
The stacking technique of rice packaging is also important to note because air ventilation between the piles must still exist to ensure minimal humidity, besides that, storage must be carried out properly.
Risk from a retail perspective in general can be illustrated in the diagram below :
Figure 8 Risk mapping for Each Division in The Whole Supply-Chain Process in Demak and Sleman
Image Source :Guritno, Adi Djoko & Kristanti, Novita & Tanuputri, Megita. (2019). Risk Mitigation on Supply Chain of Rice in Central Java Province and Special Region of Yogyakarta. agriTECH. 38. 375. 10.22146/agritech.38529.
Figure 9 Risk Mitigation Toward Each Type of Risk of Rice
Image Source :Guritno, Adi Djoko & Kristanti, Novita & Tanuputri, Megita. (2019). Risk Mitigation on Supply Chain of Rice in Central Java Province and Special Region of Yogyakarta. agriTECH. 38. 375. 10.22146/agritech.38529.
In Figure 9 it can be seen that the risk for low rice quality can be mitigated by checking the quality of rice in the field prior to purchase and the company can also funding farmers and educate on how to do good rice production. Some partnership systems by using purchase contracts with suppliers that include the desired quality standards and goods return systems also help economic losses by evaluating suppliers over time to select reliable suppliers.
Rice storage management must also implement a First In First Out (FIFO) system where the first rice that first arrives at the warehouse must be delivered out first to avoid spoilage in the warehouse and economic losses considering the shelf-life and uncertain conditions.
Security also needs to be tightened to avoid stockpiling of goods, it is better if the rice warehouse installed with CCTV and tight gate locks and guest entry and exit data has to be done out so that there is a security constraint traceability system and allows evaluation of storage security.
Distinguishing rice storage based on quality so that rice with poor quality does not spread and damage the quality of other rice while also separating rice storage from other commodities if there is any. From a commercial point of view, the warehouse company can also implement a variety of sales systems, whether retail or large quantities, and then cooperate with various distributors to ensure a smooth inventory turnover.
In addition, a risk assessment based on the quality of stock rice can also be carried out by conducting periodic quality evaluationsbystock sampling method and then looking at the reference to rice quality standards as shown in Figure 2 Standards for Rice Quality Characteristics according to the Food and Agriculture Service. If the quality turns out not qualified according to the standard thenre-checking procedure for the stock around or stock sacks with a similar supplier codehave to be done, risk reference assessment areseen from these standards.
In the level of mitigation for risks related to physical factors we can look at the rice storage system in India the Food Corporation of India (FCI) which is the best storage management system with a storage loss of only 0.3% for 3 years. Storage Loss usually ranges from 1-2%, especially in developed countries when grain is stored in well-managed silos with aeration and drying.
However, Storage Loss may be as high as 20-50% in less developed countries. The storage system in India is Silo which is used for rice storage in India for the last few years. These are steel or concrete circular silos with storage capacity ranges from 350-600 metric tons. But only Silo bottom hoppers are now used for rice storage.
Figure 10 Silo Bottom Hopper
Image Source :https://indonesian.alibaba.com/product-detail/conical-silos-storage-hopper-bottom-grain-60420567692.html
Besides, air ventilation in the storage warehouse must also be considered, allowing air exchange to occur so that air circulation is maintained and humidity can be more controllable. Air ventilation can be controlled by adding an exhaust fan to the walls of the warehouse. In addition, to control the actual temperature, an air cooler can be installed in the warehouse and a thermometer system is installed to measure and ensure the air temperature is maintained at the limits mentioned above.
Figure 11 Warehouse Air Circulation System
Image Source : https://www.waterlinecooling.com/en/factory-cooling-ventilation-system/
You could say that rice warehouse storage is more ideal, you can use a Controlled Atmosphere Storage system to control temperature, humidity and air aeration.
According to research by Pitaloka, et al (2012), physical factors play a role in roofs, floors, walls, ventilation, doors, drainage channels, toilet facilities and lighting in warehouses and floors. This research concluded that it turns out that the drainage channel is important to pay attention to, for example garbage that pools/accumulated in the drainage channel, or low drainage can potentially causes more humidity and affects the moisture content of the commodity, also a lot of rice being scattered on the floor will invite insects population too.
So it is important to build a good drainage system, but it can also be strategized by making the height of the warehouse higher than the adjacent land and distance from areas prone to waterlogging, canals, and flood-prone areas to prevent flooding in the area. Because where there is a channel, it is prone to flooding and the channel has a tendency to become a breeding ground for insects and pests.
Figure 12 Warehouse/Industrial Water Drainage System
Image Source : https://global.hauraton.com/en/application-area/industrial-drainage/
In addition, keeping floors and machines clean so that they are free from dust, contaminants/waste, scattered rice, especially organic waste, they must be swept periodically or vacuuming can be done once a week.
In terms of lighting, in general dark place will be preferred by insects, besides that, fluorescent lighting for physical warehouse lighting should use the standard 100 watt/m2. All this control and conditioning is aimed to control physiological and chemistry risk factors. In addition, the light intensity during the day can also be adjusted to reach 13 –79 flux, so the warehouse window must also be ensured to be ideal and sufficient, as well as checking the light intensity from the lamp as well.
In addition, the roof of the warehouse and the walls must continue to be evaluated, especially during the rainy season whether there is a roof with holes or is there an area of the wall where rainwater can still seep in and then whether there are holes in the walls. If there is, it must be addressed immediately because rice is sensitive to water content.
The actions and physical aspects above are intended to prevent unwanted chemical and physiological risks.
Most rice storage is packaged with a size of 40-80 kg made of jute or woven plastic, but it is recommended to use a hermetic system because it can maintain the initial moisture content of the goods and it is airtight so that it is low in O2& pests cannot live within O2deprived condition. An example of hermetic material is IRRI Super Bags. (as in the picture on the left)
Then after the packaging is stacked it can be covered by a waterproof tarpaulin or dunage material as additional protection for the sack against water and others.
Figure 13 Rice Sack Tarpaulin Closure with 800–1,000 . thick Polyethylene Sheet material
Image Source: https://www.frontiersin.org/articles/10.3389/fsufs.2021.675626/full#F3
The storage method also relies on wood crates or wooden pallets at the bottom of the pile of sacks so the sacks are not directly placed on the floor to be safe from insects, floor dirt and also in an effort to maintain air circulation / aeration and eliminate the possibility of sacks absorbing moisture / floor moisture content.
It is also important to pay attention to the packaging stacking method to maintain air aeration.
Figure 14 Rice Bag Stacking Methods
Image Source :https://hpt.faperta.ugm.ac.id
Another thing to consider when stacking rice sacks is that the sacks should not be stacked higher than 4 meters for jute sacks and 3 meters for plastic sacks because plastic sacks are more slippery and the pile will be less stable. The higher the pile of sacks, the more difficult it is to fumigate. For biological risk factor mitigation of pesticides, fumigation can be carried out every 2 weeks
In my opinion, risk control is carried out with a periodic evaluation system, for example by:
a) Moisture content measurement: Measured at the time of stacking of the entire pile; every two weeks by taking a sample from the edge of the pile; and at the time of liquidation by sampling from the entire stack.
b) Parameters of pile quality, done every two weeks by taking samples from the edge of the pile and carrying out Quality Control with standard reference to Figure 2
c) Infestation rate: Monthly by sampling from the edge of the pile.
d) Observation of pests such as rats, birds, mites, etc. during storage: Every 2 weeks or once a month by visual observation.
e) The application of fumigation with fumigant drugs for food commodities with active ingredients Phosphine (PH3) such as Fumiphos 56 TB tablet or liquid gas fumigant Fumilikuid 2 GA.
It is also possible to sanitize the environment around the warehouse by spraying the environmentally friendly insecticide Silogud 250 EC with the active ingredient Methyl Pirimiphos (C11H20N3O3PS) on the outer edge of the rice pile twice a week.
f) Recording of spillage: Spills are collected every 15 days and placed in a bag attached to each pile (called a palla bag).
g) Occurrence of theft, if there are anyoccurence: The depot officer reports the information to the competent authority.
h) Mycotoxins: Recorded only when suspected.
i) Reweighing stock samples to assess the level of storage loss
j) Doing stock calculation/assessmentperiodically and evaluating suppliers
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