1. PRESENTED BY DR. GABRIEL I. OKAFOR DEPT. OF FOOD SCIENCE AND TECHNOLOGY, UNIVERSITY OF NIGERIA, NSUKKA, ENUGU STATE, NIGERIA. gabriel.okafor@unn.edu.ng 08023423908 gabriel.okafor@unn.edu.ng PRINCIPLES OF SAFE FOOD STORAGE FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

2. Salutation …Warm greetings from the University of Nigeria- The cradle of university education in Nigeria FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015.

3. OUTLINE Food Storage Principles IntroductionJustificationsPrinciplesPractice FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

4. INTRODUCTION: FOOD STORAGE Maintenance of commodities, such as fresh or processed foods, under controlled conditions for extended durations, while maintaining quality (IFIS, 2005). Keeping food for future usage/consumption. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

6. FRESH PRODUCE Undesirable quality changes such as changes in nutrient levels, colour, development of off-flavor or loss of texture may occur. Therefore, careful control of atmospheric gases, such as oxygen, carbon dioxide and ethylene (controlled atmosphere storage), is important in extending the storage life of many products, such as fruits and vegetables. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

7. FATE OF PROCESSED FOODS Canned foods or dried foods, are processed in such a way that they may be kept at ambient temperature with no loss in quality. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

8. PRINCIPLE Means:  a ​basic ​idea or ​rule that ​explains or ​controls how something ​happens or ​works (Cambridge Dictionary)basicidearuleexplainscontrolshappensworks  a general scientific theorem or law that has numerous special applications across a wide field.  a fundamental truth or proposition that serves as the foundation for a system of belief or behaviour or for a chain of reasoning. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

9. JUSTIFICATIONS To enhance food security. Market price stabilization. Industrial utilization. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

10.  To reserve for future planting.. To reserve for future planting. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015  To store semi-processed product  To store finished product for efficient distribution  To enhance farmers income.

11. Food deteriorates soon after harvest NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Causes  Biological interactions  Post harvest losses  Chemical breakdown of food components catalyzed by energies, light or water.  Presence of enzymes which catalyze reactions that may be detrimental to product quality such as: i.flavor production by lipoxygenase, lipases and proteinases, ii.textural changes due to pectic enzymes and cellulases. iii.colour changes due to polyphenol oxidase, chlorophyllase and peroxidase. iv.Nutritional Changes due to ascorbic acid oxidase or thiaminase

12. Insect and Rodent Attacks Insect and rodent infestations and associated losses occurs readily in open fields, during growth and production, in bulk stores of food exposed or partially exposed to the environment. Rodents damages far more food than they consume through adulteration with droppings, filth, hair and potential transmission of diseases. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

13. Varying Temperature Conditions NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Uncontrolled heat or cold causes detrimental reactions in foods. 30-40 0 C Accelerates rate of reactions i.e oxidation producing off- flavours, colour changes, nutrient loss, decreased generation times of microorganisms leading to enhanced population. 0-15 0 C  Can lead to detrimental physiological reactions in certain susceptible produce; i.e. chill injury (tomatos or bananas)  Cold shortening in meat (toughens carcass after slaughter.  Chill sweetening in potatoes increasing glucose content, causing enhanced browning during frying.  Staling of bread

14. Moisture Content Plays critical role in microbial growth and chemical reactions. Water activity (a measure of free water in food) has been used widely as a measure of food stability. Gain or loss of H 2 O from a food due to its condition of storage may influence the water activity and solute diffusion rates – microbial and chemical stability. Changes in relative humidity (RH) of storage affects structure and texture of food. i.High RH increases splitting or cracking of skins of fruits. ii.Reduced RH – drives wilting and shriveling of fruits and vegetables leading to a loss of weight and economics value. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

15. Oxygen  Microbial activities are O 2 driven (aerobic, anaerobic or facultative organisms with wider tolerances).  O 2 is an initiator of chemical reactions detrimental to various food constituents (lipids, vitamins, pigments, and some amino acids).  Reduced O 2 can impair physiological functions of food tissues such as fruits, vegetables or meat. Therefore, control of O 2 contents in food storage through modified atmosphere and protective packaging helps. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

16. Light Exposure to light is detrimental to some food products. Light can promote oxidative rancidity of lipids i.e oxidation of milk leading to breakdown of proteins and formation of unpleasant volatiles. Changes in pigments (myogbin in red meats) Breakdown of vitamins (A, C and riboflavin) Development of potentially toxic light induced glycol alkaloids such as solanine in potatoes (turning green due to increased chlorophyll content from light exposure). NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

17. Time  Plays a great role in food spoilage/deterioration.  All foods will become unconsummable over time. – Canned foods could last for several years. – Pasteurized/refrigerated foods could last for days/weeks/months. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

18. Food materials are stored that: Quality will not deteriorate from loading time to as long as required. Quantity is not unintentionally lost. Secured against pests, diseases and physical loss. It is accessible at the time and in the quality required NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

19. Primary target Protection of stored commodities against external elements : Temperature and humidity, Pests and theft Product of respiration Heat, moisture, gases (CO 2 + ethylene). NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

20. Traditional storage methods Inefficient, causes high loss, insecure, inflexible Still used, serves farmers well especially small small scale farms Rely on basic good storage management and use of traditional methods of pest control to minimize losses. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

21. BASIC CONSIDERATIONS FOR EFFICIENT STORAGE A good store must be selected and prepared. Commodities must be received in good condition. Intake must be orderly and recorded. Quality maintenance must be assured. Security against theft and loss must be provided Any loss incurred must be identifiable and accountable. The end use requirement must be met. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

22. SAFE FOOD STORAGE PRINCIPLES NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Storage structure  Must be suitably located Conducive climate Adequate load bearing capacity (soil tests needed) Dry land (all seasons) Flat sites better Orientation of building using wind direction and sunrise/sunset. Avoid natural wind tunnel between two hills (dust, sand etc).

23. Design Consideration  Must be properly designed to offer protection against rain, ground water, adverse temperature, pests and thefts. Should facilitate its management i.e loading/ unloading, maintenance, access to roof and drains, general working conditions for safety, comfort and efficiency. lighting should be adequate. Should facilitate efficient stock control (First In First Out - FIFO) and commodity inspection, Should facilitate pest control, cleaning. Must enhance air flow NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

24. Fig. 1: Store design with respect to moisture NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Protection against moisture Golob, et. al. (2002).

25. Protection against temperature NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Golob, et. al. (2002). Fig. 2: Store design with respect to temperature

26. Controlled atmosphere NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Fig. 3: Store design relative to atmosphereGolob, et. al. (2002).

27. Store design with respect to security NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Golob, et. al. (2002). Fig. 4: Store design with respect to security

28. Store design with respect to bird control NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Golob, et. al. (2002). Fig. 5: Store design with respect to bird control

29. Store design with respect to rodent control respect to rodent control. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Golob, et. al. (2002).Fig. 6: Store design with respect to rodent control

30. Store design with respect to insect control NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Golob, et. al. (2002). Fig. 7: Store design with respect to insect control

31. Store design with respect to management NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Golob, et. al. (2002).Fig. 8: Store design with respect to moisture

32. Storage of horticultural produce From simple rooms, containers to refrigerators Product requirements  Temperature sensitive crops should be held above 10-12 O C or chilling injury may occur.  Crops not sensitive to chilling injury be may be stored at temperature as low as 0 O C. Principle of cold storage  Reduction of respiration rate, browning reaction, sprouting, softening and decay of vegetables and fruits. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

33. Fig. 9: Design for a small-scale cold room store. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Source: Thompson & Spinoglio 1994. Efficient Temperature Control  Remove field heat  Provision of good cold storage space with insulation  Use thermostat  Monitor pulp temperature Cold room store design

34. Determination of size of refrigeration unit required NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 The is determined by:  the weight of produce to be cooled.  the minimum time required from start to finish of cooling  the nature of the refrigerated space – size, degree of insulation and how it is to be operated.  The amount of refrigerated space required can be determined by: V = 2.5 × (C + S), where: V = volume of the refrigerated space in cubic feet; C = maximum number of bushels to be cooled at any one time; and S = maximum number of bushels to be stored at any one time.  Cooling room floor area = V/H, where: H - ceiling height in feet, (H should not be 18 inches greater than the maximum stacking height of cooled produce)

35. Calculation of heat load NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 The correct refrigeration unit will depend on the total amount of heat that the unit must remove from the cooling room, known as the heat load. According to Boyette et al. (1989) heat load components are as follows:  Heat conduction – heat entering through insulated walls, ceiling and floor.  Field heat – heat extracted from produce as it cools to storage temperature.  Heat of respiration – heat is generated by the produce as a natural by-product of its respiration.  Service load – heat from lights, fans, people, and warm, moist air entering through cracks or through the door when opened.

36. Relative Humidity Reduction of Moisture Loss NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015  Weight loss of produce occurs due to moisture loss (invokes impaired visual appearance and consumer acceptability).  Produce stored at 25 O C and 30% relative humidity will lose moisture 36 times faster than those stored at 0 O C and 90% RH.  Optimum relative humidity for fruits = 90-95%.  Humidifier should be used if RH inside the refrigerated storage is less than 90%  Monitor RH of the storage with a hygrometer.

37. Controlled atmosphere storage (CA) NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Control of the levels of certain gases around and therefore within fruits and vegetables. Requires consistent monitoring of CO 2 and O 2 levels, and gas leakages through doors and walls.  Metabolic activity changes composition of gases in store.  Fresh air or nitrogen may be introduced or storage atmosphere passed through a chemical. TYPES OF CA Static CA Storage – Product generates the atmosphere. Flushed CA storage – Atmosphere made from constantly supplied gas.  Initial flushing to reduce O 2 content  Injecting CO 2 or building it up  Maintenance of atmosphere by ventilation and scrubbing i.e selective removal Optimum storage condition for CA Apples – 1.5% O 2 + 1% CO 2 t= O C in Australia 3% O2 + 2-4% CO 2 t = 0.5 O C in Spain  Variation of condition = soil and climate types, post harvest treatment etc.

38. Gas control NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Central to the design of a CA storage system is the selection of the most appropriate equipment for creating and maintaining the selected gas concentrations in the store, by:  removal of ambient oxygen (by nitrogen flushing)  removal of carbon dioxide by respiration  Ca(OH) 2 scrubber that absorbs CO 2 to produce CaCO 3, H 2 O and heat;  Use of renewable scrubbers – Activated charcoal (active carbon) Molecular sieve (aluminium calcium silicate)  addition of air to replace oxygen consumed by respiration;  removal of ethylene using KMnO 4 crystals or metal catalysts at high temperature; and  addition of carbon dioxide.

39. Modified Atmosphere (MA) Packaging of fruits of vegetables in a plastic film that slowly allows passage of respiratory gases i.e Increased CO 2 and reduced O 2 than exist in air (Thomson, 1998). An action of required composition created by respiration or mixed and flushed into the product enclosure (Bishop, 1996). Three main gases used commercially in MAP are oxygen, carbon dioxide, nitrogen (nitrogen is used as a filler gas to prevent pack collapse, which may occur in atmospheres containing high carbon dioxide) and novel gas mixtures (e.g. argon and nitrous oxide). NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015

40. Permeability of Modified Atmosphere (MA) Film NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015  Low permeability of film damages due to accumulation of water or carbon dioxide or depletion of oxygen.  Holes can be punched in the film to improve ventilation.  Film permeability to gases is by active diffusion where the gas molecules dissolve in the fi lm matrix and diffuse through in response to the concentration gradient (Kester & Fennema, 1986).  Crank (1975) proposed formula to describe film permeability is: where J = volumetric rate of gas flow through the film at steady state, x = thickness of film, A = area of permeable surface, p1 = gas partial pressure on side 1 of the film, p2 = gas partial pressure on side 2 of the film

41. Interrupted controlled atmosphere storage NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Controlled atmosphere storage have detrimental side-effects on fruits and vegetables, and the possibility of alternating controlled atmosphere storage with air storage has been studied. Results revealed that  Banana cultivar Poyo (from Cameroon) stored at 30–40°C and interrupted by one to three cooling periods (20°C) of 12 hours either in air or in atmospheres with 50% oxygen or 5% oxygen. Cooling periods were found to reduce high temperature damage, especially when fruits stored at 30°C received three cooling periods in 50% oxygen (Dick & Marcellin, 1985).  Intermittent exposure of avocado cultivar Haas to 20% carbon dioxide increased storage life at 12°C and reduced chilling injury during storage at 4°C compared to those stored in air at the same temperatures (Marcellin & Chaves, 1983).

42. Controlled atmosphere transport NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Large quantities of fresh fruit and vegetables are transported by sea-freight refrigerated (reefer) containers. It was estimated that the world fleet increased four-fold from 1993 to 1997 when there were around 38000 reefer containers (Dohring 1997). Relatively small but increasing numbers of containers (approximately 1000 containers) are being used for the CA transportation of fresh fruit and vegetables. Such as apples, apricots, asparagus, avocados, bananas, broccoli, mangoes, peaches, nectarines, pears, pineapples, plums, sweetcorn and tomatoes. A number of technical problems hindering the use of CA transportation in the past (the lack of gas-tight containers, suitable systems for gas control and analysis, and adequate CA-generating systems) have now largely been overcome. A common problem was the maintenance of gas-tight conditions.

43. Hypobaric (low pressure) storage NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Involves cold storage of fruits under partial vacuum.  Typical storage condition includes pressure as low as 80 and 40 millimeters as mercury and temperature 5 O C.  Hypobaric conditions reduce ethylene production and respiration rates. The result is an extra ordinarily high quality fruit even after months of storage.

44. Total nitrogen or high nitrogen storage NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 The storage of some fruits in total nitrogen or nitrogen-rich atmospheres can be beneficial (Thompson 1998).  Ripening of plums stored in total nitrogen has been reported to be almost completely inhibited (Anon. 1920).  Plums were able to tolerate, for a considerable period, an almost complete absence of oxygen without being killed or developing an alcoholic or unpleasant flavour.  Strawberries, 100% and 99% nitrogen atmospheres reduce mould growth during 10 days of storage at 1.1°C with little or no effect on flavour (Parsons et al. 1964).  Decay of peaches, was reduced during storage in either 100% or 99% nitrogen at 60°F;  Off-flavours were detected in fruit after 4 days in 100% nitrogen, but none in those stored in 99% nitrogen.

45. Ethylene Effects NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015  Affects ripening of climacteric fruits and vegetables.  Breaks down chlorophyll content of non-climacteric fruits and vegetables.  Ethylene sensitive and ethylene producing commodities are not to be stored together. Table : Ethylene-sensitive and ethylene-producing crops.

46. Odour compatibility Many commodities produce odours that are easily absorbed by others. Smelly commodities should not be stored with non- smelly ones. i.e oniony cabbage. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 (Source: Gast & Flores 1992). Table 2: Odour compatibility between commodities.

47. REFERENCES NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Anon. (1920) Food Investigation Board. Department of Scientific and Industrial Research Report for the Year 1920. pp 16–25. Bishop, D.J. (1996) Controlled Atmosphere Storage. A Practical Guide. David Bishop Design Consultants, Sussex, UK. Boyette, M.D., Wilson, L.G. & Estes, E.A. (1989) Design of room cooling facilities: Structural and energy requirements. AG-414–2. North Carolina Cooperative Extension Service, USA. Crank, J. (1975) The Mathematics of Diffusion. Second Edition. Oxford University Press, New York NY, USA. Dick, E. & Marcellin, P. (1985) Effect of high temperatures on banana development after harvest. Prophylactic tests. Fruits, 40, 781–784. Dohring, S. (1997). Over sea and over land: Putting CA research and technology to work for international shipments of fresh produce. In: Seventh International Controlled Atmosphere Research Conference, 13–18 July 1997. University of California, Davis CA, USA. Gast, K.L. & Flores, R.A. (1992) MF-1033. Storage operations. Fruit and vegetables. Postharvest management of commercial horticultural crops. Cooperative Extension Service, Kansas, USA.

48. REFERENCES Contd….. NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015 Kester, J.J. & Fennema, O.R. (1986) Edible fi lms and fi lm coatings: a review. Food Technology, 40, 47–59. Golob, P., Farrell, G. and Orchard, J.E. (2002). Crop Post-Harvest: Science & Tech. V. 1. Principles and Practice. Blackwell Sci. Ltd, Gosport, UK. Marcellin, P. & Chaves, A. (1983) Effects of intermittent high carbon dioxide treatment on storage life of avocado fruits in relation to respiration and ethylene production. Acta Horticulturae, 138, 155–163. Parsons, C.S., Gates, J.E. & Spalding, D.H. (1964) Quality of some fruits and vegetables after holding in nitrogen atmospheres. American Society for Horticultural Science, 84, 549–556. Thompson, A.K. (1998). Controlled Atmosphere Storage of Fruits and Vegetables. CAB International, Wallingford, UK. Thompson, J.F & Spinoglio, M. (1994) Small-scale cold rooms for perishable commodities. Family Farm Series. Small Farm Centre, University of California, Davis CA, USA.

49. THANK YOU FOR LISTENING NIFST'S FOOD SAFETY MANAGEMENT TRAINING WORKSHOP, OWERRI, OCT. 2015