Blog Details

S.No

Product detail

Ethylene Concentration (ppm)

Ethylene Exposure Time

(hours)

Ripening

Temperature (o C)

Storage

Temperature

After riping (o C)

1

Banana

100-150

24-48

15-18

13-14

2

Mango

100

24

20-22

10-13

3

Papaya

100

24-48

20-25

About at 7

4

Pears

100-150

24-72

18-22 Tomatoec

About at 0 oC

5

Tomato

100-150

24-48

18-20

12.5

S.No

Item/Particular

Minimum Technical Specifications

1

Civil Structure- building design

Civil Structure a. Structural Safety – Structural design as per BIS Code b. Adherence to local Building Regulations c. Concrete floor with sufficient load bearing capacity. d. Chamber size is not smaller than 50 Cu M for preventing building up of high concentration of ethylene.

2

Ripening Room Dimensions

a. Ripening Room dimensions will depend on number of tiers and number of pallets to be stored. On an average 11M3 per MT of banana fruits in ripening units for 10 MT or larger capacity and 12 M3 /MT for ripening units of less than 10 MT capacity. For this purpose, volume of one chamber is taken in to account. b. Number of chambers may vary from four to eight depending on ripening cycle in terms of number of days. Chambers will be generally identical in dimension. In low cost solution, one ethylene exposure chamber may be accompanied by single storage hall of, say, four times the size of the former. However, in such low cost solutions, lots of different ripening stages being stacked together, it may not be possible to provide temperature conditions recommended for each of them. c. Further Increase in number of chambers in multiple of ripening cycle may be undertaken but situation in which mechanised handling is possible, multi tier ripening chamber is an alternative option available. Number of tiers may go up to three.

3

Ripening Room Construction

Construction Features a. Ripening Room Chambers should be designed and constructed to hermetically seal with appropriate closures / doors. The key feature of ripening rooms is that conditioned air is forced through the product rather than the product just being stored in a temperature controlled room. The system passes air though each pallet or series of pallets before returning to the evaporator. Therefore, any “air-stacking” or “cross-stacking” of boxes is not necessary, and the result is less space requirement, lesser handling of the fruit and improved product quality. It is for this reason that they are recommended even for ripening of fruits in crates and are mandatory for fruits in CFB boxes and single or multi-tier stacking system. b. The airflow within the ripening rooms is to be designed to penetrate all boxes of fruit with an even airflow throughout the room resulting in all fruit being ripened uniformly. Recommend air flow is 0.3 cfm per pound of bananas or 2000 m3/ per hour / per metric ton of product. If the pulp temperature difference between the warmest and coolest fruit is less than 1o F or 0.55o C then there is adequate airflow. Plenum chamber is recommended so as to equalise pressure through the product for uniform distribution/flow of air and ethylene through the product. c. Ripening rooms may be constructed of PUF panels or by application of suitable thermal insulation with vapour barrier and cladding on walls, floor and ceiling of civil structure. Panels are prefabricated building components filled with insulation, clad on both sides with facing materials and arranged with a jointing means to connect panels and may be preferred. In any case, inner chamber surface should be of food grade cladding. d. The insulation envelope shall be designed to ensure that air pressure created by fans does not affect the integrity of the cold store structure or the panel joints. e. The height of wall panels is often such that care must be taken to ensure that adequate stability of the wall panels is maintained. If ceiling support are provided, the Ceiling support system shall be connected to the main structure in a manner which takes into account: i. The method of supporting the insulating ceiling panels, ii. The position of the supports to avoid local over stress within the supports, the suspended ceiling or the main structure, iii. The expansion and contraction of the main structure.

4

Riping Room Door

Ripening doors should be designed for minimal gas leakage. In general. i. For single tier loading, hinged doors, and in some cases, sliding doors are used. The doors should be designed for rugged operation and easy access for incoming and outgoing fruits on pallets. ii. When stacking is multi-tier and handling of pallets is mechanised, wider openings of doors are required. iii. Care should be taken when positioning doors adjacent to fans to avoid ingress or egress of air as significant changes in store pressure can occur when such doors are opened.iv. Where possible the door should be located on the external (warm side) of the cold store insulation. v. Suitable gaskets shall be provided to form a seal around the door opening. vi. Large doors shall be supported by a sub-frame independent of the insulating panels. vii. Automatic doors shall open and close promptly. viii. Automatic doors shall incorporate a safety device to avoid injury to personnel or damage to product in the case of accidental closure. ix. All doors required for means of escape purposes shall be easily and immediately operable from the inside at all times. Doors, which open automatically, are not acceptable for means of escape unless they have a manual override and can be opened manually in the event of a power failure. x. In case of multi tier stacking, doors are rolling up type and therefore, following desirable safety features for doors should be ensureda. Internal Door Release b. Bottom Edge Pressure Operated Safety Stop c. Cable Break Electrical Safety Stop d. Spring Break Mechanical Safety Stop e. Vision Panel with emergency Knock out panel f. Vertical “D” section flexible seal for effective sealing in condition of reverse airflow for uniform ripening. Seal should be strong enough to withstand impact from pallets during loading operations and flexible enough to create an adequate seal between air distribution system and product. Horizontal pallet seals should be supported continuously along the full length of room but should be easy to remove a seal for cleaning or replacement. g. Door protection by Goal Post Protection which protect door perimeters or Single Fixed Bollards doors suitable for ripening chamber.

5

Insulation material

i.                     INSULATION MATERIAL a. Some manufacturers recommend Rockwool or Polyisocyanurate (PIR) core composite panels for fire proofing. However, Polyurethane (PUR) Foam / EPS / Extruded polystyrene are also used.

b. PUF panels are advisable for ripening chambers. Minimum 60 mm thick up to 120mm thick (PUF) insulated sandwiched panel (minimum density of 40 Kg / M3 ) depending on the design requirements; or any other insulation material having minimum R value of 2.6 M2 .K / W are recommended for easy in-situ construction and vapour barrier effect. Floor shall have PUF slab 60 mm (minimum density of 40 Kg / M3 ) or any other equivalent insulating material is recommended. c. Covering floor insulation with 100mm concrete is recommended. Floor finish should be smooth with polymer coating so has to be kept clean. ii. FACING MATERIALS- One of the following coverings may be used; the first three are used more frequently than the others and a minimum total coated thickness of 0,5 mm is recommended. A vapour seal shall be used on the outer facing of materials, which are permeable, such as brick masonry: a. Galvanized steel sheeting b. Suitable plastic coated galvanized steel sheeting c. Polyester coated galvanized steel sheeting d. Stainless steel sheeting e. Aluminium sheeting f. Aluminium/zinc protected steel sheeting g. Glass reinforced plastics iii. ADHESIVES a. Certain adhesives have a combustible solvent base which can be absorbed by and remain in the panel insulation. These solvents should, therefore, be avoided. b. Certain adhesives should be stored under controlled conditions and the manufacturer’s requirements should be strictly observed; many adhesives have a maximum shelf life. c. Adhesives should not have a lingering taint

6

Temperature & Humidity levels

Ripening is preferred at a lower temperature but above level of chilling injury. System has to be designed to achieve prescribed ripening conditions in terms of temperature and relative humidity for target fruits. Generally, RH level of 90- 95% is recommended to prevent moisture loss.

7

Heat Load Calculation and Refrigerant

Cooling and heating system needs to be designed based on heat load calculation. As per Kyoto Protocol standards, any ecofriendly refrigerant should be used including ammonia, R-134a and R 404a.

8

Cooling / heating coils and plenum Chamber

a. Cooling coils are manufactured from Copper or Stainless chamber Steel Tubes and Aluminium Fins. The coils must provide exceptionally large surface area to ensure high natural humidity levels within ripening rooms. In case of ammonia as refrigerant, copper tube shall not be used. b. In case of a plenum chamber; cooling coils and fans must be easily accessible via single access hatch located above or at the end of the plenum chamber at roof level. Ceiling voids should be fully illuminated to facilitate inspection of coils at regular intervals. c. Electric heating elements should be used for heating ripening room during lower temperature season as per design requirement and be placed in easily accessible locations. Open flame type chamber heating should never be used due to explosive nature of ethylene. d. Fixing of the cooler shall be arranged to avoid disturbance of the ceiling panel support system. Ceiling panels in the vicinity of the cooler units will be subjected to continual variations in temperature and therefore, relative movement during defrost cycles.

9

Material to be used for ripening

Ethylene gas with suitable detection and dosing equipment to maintain ethylene concentration within required levels depending on product (Range 10 to 200 ppm).

10

Ethylene Generator and Dosing device

a.       Ethylene may be introduced in ripening chambers in one of the three ways- by using independent ethylene generator with regulator; ethylene cartridges and ethylene-nitrogen mixture (5% ethylene + 95% nitrogen) cylinder. Whichever method is used, the duty holder should ensure that there are adequate means of dispersing the ethylene gases throughout the ripening room on its release. b. Centralized Ethylene supply with Automation for multiple chambers for controlled and safe dosing of ethylene may be preferred for larger units. c. If a generator containing ethanol based solution requires to be moved, it should be switched off, the mains cord removed from the socket outlet, and the manufacturer’s instructions closely followed.

d. It may be borne in mind that ethylene in concentration above 27000 ppm may explode.

11

Specification for Air circulation system

i. Minimum air flow should be 2000 M3 per hour, per MT of product ripened at 95%. ii. In Ripening Units type-1, air circulation is modified for uniform ripening by introduction of system of Tarp, Tarp/ Lock Sock System / Air Bag for Vertical Air Circulation or Horizontal Air Flow. iii. In case of Ripening Units type -2, air circulation fans should have adequate static pressure for uniform air/ ethylene flow through the ventilation holes provided in the CFB boxes/ Plastic Crates / Plastic Bags containing fruits. For this, large diameter, reversible axial flow fans should be installed in the false ceiling accessible via a single access hatch for air supply under pressure. Each fan should preferably be equipped with venturi inlet to provide maximum efficiency throughout the ripening process. In such cases, pallet isolation must be provided for energy savings in part load conditions by providing a series of isolation dampers along the length of the ripening chamber. This function is operated by making proper selection for pallet isolation on Computerised Ripening Room Management System.

12

Ventilation System

a. When fruits are ripening, they release carbon dioxide which will build up in a ripening room. The CO2 production begins as the fruit ripens enters the “climacteric” phase, or the period when bananas release ethylene and have an elevated rate of respiration (along with a great deal of other physiological changes). Respiration involves the uptake of oxygen, the release of carbon dioxide, and the breakdown of starches. Carbon dioxide concentrations above 1% (10,000 ppm) will retard ripening, delay the effects of ethylene and cause quality problems. Suitable venting system consisting of fans/dampers/open – shut valves should be installed to maintain CO2 concentration below 5000 ppm. b. In ripening rooms Type-1, ventilation may be automatic or manual. c. In case of ripening rooms type-2 with pallet isolation, ventilation may be provided by a roof mounted fan which is identical in specification to the pressure fans. d. In case of automatic forced air exhaust / ventilation system with ducting, a dual inlet / discharge damper

13

Sensors and Control devices

operates in parallel with the fan to allow fresh air from outside to replace the air within the room when vent is

required. Automatic exhaust fans (either timed or sensorbased) or “flow-though” (constant) ventilation are provided at two locations (one near ceiling of chamber and another a little above floor level) in each chamber. This also evacuates the ethylene after the desired exposure period and helps to maintain CO2 concentration low (below 5000 ppm) during the ripening cycle for proper ripening. In such cases, opening and shutoff actuators/ valves control is affected by CO2 sensor and timer device

a. Suitable sensors and controlled devices should be used for maintaining following parameters. For this, temperature & humidity loggers and Ripening Chamber Air Analysis Kit (for Ethylene and CO2 levels) may be used. i. Temperature ii. Relative humidity iii. Ethylene concentration iv. CO2 Concentration b. PLC device also known as Ripening Room Management System –”RMS” is must in Ripening Unit Type-2. The controller provides total control of the ripening system allowing operators secure and password protected access to following functionsc. Clear real time temperature display and control d. Fan speed and energy usage e. Ventilation intervals f. Relative humidity indicator and control g. Ethylene level monitoring and regulation h. Door control i. Lighting control j. Pallet loading and isolation k. Differential Pressure DisplayDifferential Pressure Display provides the ripener with an indication of air pressure drop cross the fruit pallets. This information along with information from Temperature. Ethylene gas censors located inside chamber, within pallets and within boxes / plastic bags, is used to determine the setting of the inverter drive based on factors such as the type of product packaging and fruit, amount of pallets in the room and current stage of the ripening process. The RMS for multichamber pressure ripening system should preferably be able to be configured to allow all rooms to be viewed and controlled locally and, or remotely.

14

Electrical plug point

a. For operating Portable Ethylene Generator, an Electrical Plug point is required inside the room. Metal Clad Plug point in the Metal Socket housing with the independent circuit breaker system, in order to isolate the system independent with the rest of the System, is recommended. b. For centralized gas emission, no electrical connections are required inside the room.

15

Pallet Racking and Material Handling

a. Ripening unit with single tier stacking should have a manually operated pallet lifting and carrying device. Pallet racking system comprises of box section construction which may be designed as per BS 5950 or equivalent IS standards for strength and cleanliness, providing easy access for pallet loading at high level. b. For multi-tier stacking motorised forklift should be provided. In such cases, in order to assist loading at upper levels, fork lift guides are to be installed to form a centre aisle which are strengthened by back filling with concrete. These guides are to be tapered at the front. To facilitate loading and centralising the fork lift truck in the drive in racking, the middle and upper tiers of racking are offset from the lower tier. An access ladder is also provided to the rear wall for access to an optional grated walkway at middle and upper pallet levels. c. Typical palletisation systems are shown in Section 3.

16

Some Useful Appliances and instrument

Weighing Scales and Fruit Inspection Instruments such as Instruments follow. Weighing Scale b. Firmness Tester c. Refractometer d. Sizers and Callipers e. Produce Knife

17

Safety Certification

I.                     Various fire detection and prevention systems and devices are commercially available and use of these is good practice. They include detectors for heat and smoke; fixed water-sprinkling system, inert gas snuffing systems,

II.                   smoke release valves, flameproof barriers, fire breaks formed by the separation of chambers, etc. All devices used shall have been tested at low temperatures and shown to be satisfactory. II. Certification for safe storage of ethylene and for system for prevention of ignition and explosion from competent authority, as per statutory requirement, if any, must be taken. Similarly, safety for workers against suffocation must be ensured. Certification from following Certification Authority is necessarya. Factory Inspector b. Fire Fighting Inspector c. Electrical Safety Inspector