GB/T 23897-2024Technical code of practice for postharvest handling of major cut flower products (English PDF)

1 Scope

This document establishes the procedure for the postharvest handling of major cut flower products, specifies the operating instructions for the stages of pretreatment, quality grading, bundling and packing, rapid precooling, short-term storage and low-temperature transport, and describes the traceability method for the postharvest handling process.

This document applies to the postharvest handling of major cut flower products.

3 Terms and definitions

The following terms and definitions apply to this document.

3.1 Pretreatment solution. A solution containing a bactericide, a respiration inhibitor and similar agents, used on cut flowers after cutting and before packing to improve their tolerance of storage and transport.

3.2 Precooling. The cooling process by which, after cut flowers have been graded and packed and before they are stored and transported, forced convection of cold air, a vacuum environment or a similar means is used to bring the temperature of the flowers down quickly to the temperature required for storage and transport.

4 Postharvest handling procedure

The postharvest handling procedure comprises six stages. The pretreatment stage is divided into five steps, the quality grading stage into two steps, the bundling and packing stage into six steps, the rapid precooling stage into three steps, the short-term storage stage into three steps and the transport stage into four steps. The flow of the procedure is shown in Figure 1.

5.1 Pretreatment

5.1.1 Requirements on people entering and leaving. Everyone entering the postharvest handling premises shall wash and disinfect both hands and change into thoroughly disinfected working clothes, and shall put on overshoes or thoroughly disinfected working shoes. Before leaving the premises they shall wash and disinfect their hands and take off the working clothes and working shoes.

5.1.2 Environment. The pretreatment of cut flowers is carried out in dedicated premises that are tidy, clean and free of pest and disease contamination, in which the ambient temperature and the relative humidity are kept under stable control.

5.1.3 Tools. Flower buckets, secateurs, guillotines and similar tools, and grading, bundling and other machines, shall be thoroughly disinfected before use. The disinfectant should be a chlorine-releasing disinfectant with an available chlorine concentration of 1 000 mg/L, or a 1 % peracetic acid solution.

5.1.4 Preparation. Cut flower products free of pest and disease infection and of mechanical damage should be chosen. Cut flowers entering postharvest handling shall have the leaves on the lowest quarter of the stem removed, which may be done with a leaf and thorn stripping machine.

5.1.5 Treatment with the pretreatment solution. The pretreatment solution shall be chosen according to the characteristics of the cut flower species. For ethylene-sensitive species such as carnation, gypsophila and calla lily, a cut flower pretreatment solution containing an ethylene inhibitor shall be used. For ethylene-insensitive species such as chrysanthemum and gerbera, a cut flower pretreatment solution containing another plant growth regulator shall be used. The ethylene sensitivity types of cut flowers are given for reference in Annex A. The base of the stem is held under water and 1 cm to 3 cm is cut off, and the stem is then put straight into the pretreatment solution. The concentration of the pretreatment solution shall be fixed according to the ambient temperature of the pretreatment and the pretreatment time set. Cut flowers whose base has been trimmed are immersed at once 5 cm to 8 cm into the pretreatment solution and treated for 2.5 h at 20 degrees Celsius or for 4 h at a low temperature of 10 degrees Celsius.

5.2 Quality grading

5.2.1 Environment. The requirements on the grading environment for cut flowers are those of 5.1.2, and grading is carried out at 15 degrees Celsius to 18 degrees Celsius.

5.2.2.1 Manual grading. The cut flowers, once tidied, are placed on the grading table and the length of the stem is measured against a rule. The flowers are graded by judging the size of the head, the form and colour of the flower, the thickness of the stem, the state of stem and leaf, the evenness, the mechanical damage and the pests and diseases by eye. The grading standard is GB/T 18247.1.

5.2.2.2 Machine grading may use three methods. a) Automatic grading by stem length: the length classes are drawn according to the characteristics of the species, the flowers are placed by hand at the infeed of the length grading machine, and the grading standard is GB/T 18247.1. Once sorting is complete, the material of each class is handled separately. The flowers are then graded a second time by judging the size of the head, the form and colour of the flower, the thickness of the stem, the state of stem and leaf, the evenness, the mechanical damage and the pests and diseases by eye. b) Automatic grading by stem weight: the weight classes are drawn according to the characteristics of the species, the flowers are placed by hand at the infeed of the weight grading machine, and the grading standard is GB/T 18247.1. Once sorting is complete, the flowers of each class are handled separately, and they are graded a second time by judging by eye the size of the head, the form and colour of the flower, the thickness of the stem, the state of stem and leaf, the evenness, the mechanical damage and the pests and diseases. c) Comprehensive automatic grading by image recognition: for each species and variety, a graded image database is built from phenotypic data such as stem length, degree of opening, head size, flower form and flower colour and from data on quality defects such as mechanical damage and abnormality (malformation, off colour, disease). An automatic grading model is then built for each species and variety on its database. Comprehensive automatic grading by image recognition is based on the three main parameters of stem length, head size and degree of flower opening, and is carried out according to GB/T 18247.1.

Example: for automatic grading of cut roses, eight classes are drawn on stem length, namely 45 cm to 50 cm, 51 cm to 55 cm, 56 cm to 60 cm, 61 cm to 65 cm, 66 cm to 70 cm, 71 cm to 75 cm, not less than 76 cm, and short stems (less than 45 cm); two classes, large and small, are drawn on head size; and two classes, large and small, are drawn on the degree of opening.

5.3 Bundling and packing

5.3.1 Environment. The requirements on the packing environment are those of 5.1.2, and packing is carried out at about 15 degrees Celsius.

5.3.2 Case sizes. The size of the packing case shall suit a pallet of 1 219 mm by 1 016 mm. The sizes of the cases used for packing, transporting and storing cut flower products follow Annex B.

5.3.3.1 Outer packing material. The outer packing material for cut flowers shall have good load-bearing capacity, shall not deform easily, shall resist crushing, shall be light and shall be suited to transport at constant low temperature. Vent holes usually have to be made at the two ends of the case, and the area of the openings is 4 % to 12 % of the total area of the face in which they are made. The strength, the closure and the other technical requirements of corrugated cases follow GB/T 6544. Common outer packing materials are polystyrene foam cases or polyethylene foam cases of a certain mechanical strength, polyester board cases lined with polyurethane foam, corrugated cases sprayed with liquid paraffin, reinforced plywood cases and crates.

5.3.3.2 Inner packing material. The inner packing material for cut flowers shall be fresh, clean, non-toxic, non-irritant, undamaged and good at holding moisture. Common inner packing materials are moisture-resistant white paper, white corrugated paper, polyethylene film, plastic sleeves and non-woven sleeves. The size of the moisture-resistant white paper or corrugated paper is 20 cm to 30 cm by 30 cm to 50 cm, and the thickness of the polyethylene plastic film is 0.04 mm to 0.06 mm. Rubber bands, string, tape and the like are used for bundling.

5.3.3.3 Filling material. The filling material may be foam plastic, inflatable plastic film, soft paper and the like.

5.3.4.1 Content of the marking on the case. The marking of the case shall follow GB/T 191 and shall include the following items and information: a) the cut flower species (to be stated on the case when the load is mixed); b) the variety name; c) the main characters such as flower colour and flower form; d) the quality grade and the number of the standard applied; e) the capacity of the case; f) the producing unit; g) the place of production of the flowers; h) the time of cutting; i) the conditions the flowers tolerate in storage and transport (gas conditions, temperature and relative humidity conditions); j) the material of the case; k) the load limit of the case; l) the size of the case; m) the commodity bar code (traceable identification code); n) marks such as this way up, keep dry and do not crush.

5.3.4.2 Content of the marking on the inner packing. The marking of the inner packing shall include the following items and information: a) the variety name; b) the main characters such as flower colour and flower form; c) the quality grade and the number of the standard applied; d) the conditions the flowers tolerate in storage and transport (gas conditions, temperature and relative humidity conditions); e) the producing unit; f) the place of production of the flowers; g) the commodity bar code (traceable identification code).

5.3.4.3 Requirements on the packing marking. The marking shall be clear, conspicuous, durable and tidy; the species, the producing unit, the trademark of the enterprise and similar items shall be marked on the display face at the front, and the other items on the side of the case. The places on the case where the marks go are shown in Figure 2.

5.3.5.1 Requirement of consistency. The cut flowers in a package shall be consistent in quality, and the quality grade of the product shall conform to GB/T 18247.1.

5.3.5.2 Case capacity. The best capacity of the case is fixed according to the species and the quality grade. Cases are filled as needed, to the point of being full, without crushing; the number of stems per bunch and the case capacity follow Annex C.

5.3.5.3 Manner of placing. The cut flowers in the case shall be placed in layers with padding between the layers. The layers are stacked head to tail in the case, with the heads outwards, 5 cm from the edge of the case. Holes shall be made in the two sides of the carton, 2 cm to 3 cm in diameter, six to eight of them, evenly spread over the side. The case is closed with tape whose length shall run beyond both ends of the case, and the outside of the carton is bound with fibre straps, three of them equally spaced round the case.

5.3.5.4 Methods of packing the heads. The method of packing the heads is chosen according to the circumstances and may be single head, aligned head, staggered head, rolled head or sleeved head. a) Single head: a single flower forms one bundling unit and is placed directly in the case. The single head method may be used for the higher quality grades of gerbera and chrysanthemum. b) Aligned head: the heads are aligned when the flowers are bundled and the bundle is tied at the base. The aligned head method may be used for cut roses, chrysanthemums and carnations. c) Staggered head: the heads are staggered when the flowers are bundled, and no tie is made near the head (or inflorescence). The staggered head method may be used for cut gerbera and gladiolus. d) Rolled head: the flowers are arranged in a single row, rolled up separated by packing paper and tied at the base. The rolled head method may be used for cut roses. e) Sleeved head: the head of each single flower is wrapped in a separate packing material and each bunch is tied at the base. The sleeved head method may be used for cut roses.

5.3.6.1 Bundling. The graded flowers are made up into a packing unit of the number of stems required for distribution (following Annex D), placed on the conveyor and bundled and packed; after bundling and packing, the corresponding inner packing code is printed and stuck on the inner packing. Within one packing unit the flowers are aligned with the cutting line of the automatic bundling equipment at the shortest stem.

5.3.6.2 Closing the case. The flowers, once inner packed, are taken off the packing machine and put in turn into the cut flower case by variety, batch and grade, and are fixed in place with straps or by adding filling material. Once the flowers are fixed, the case is placed on the case sealing machine and closed; when the case is filled the outer packing code is printed and stuck in the corresponding place on the case. Once the case is closed the flowers are placed on a pallet, arranged as required for precooling or for storage and transport.

5.4 Rapid precooling

5.4.1 Environment. The requirements on the precooling environment are those of 5.1.2. The precooling temperature shall be fixed according to the species. For species of temperate origin such as rose and chrysanthemum the final precooling temperature should generally be 2 degrees Celsius to 4 degrees Celsius; for species of subtropical origin such as gladiolus and lisianthus it should be 8 degrees Celsius to 10 degrees Celsius; for species of tropical origin such as orchid and anthurium it should be 15 degrees Celsius to 17 degrees Celsius. The classification of cut flowers by origin is given for reference in Annex A.

5.4.2 Equipment. Before the flowers are precooled the environment shall be monitored and the control equipment tested and adjusted to make sure it works properly. The refrigeration system of the precooling store shall be switched on before handling begins, so that the store is brought down to the precooling temperature set.

5.4.3.1 Cold store precooling. The flowers are put into containers holding clean water or pretreatment solution and placed in a cold store adjusted to the proper temperature, which is held constant until the flowers have come down to the temperature required.

5.4.3.2.1 Preparation for forced-air precooling. Flowers for forced-air precooling shall be properly packed. Flowers precooled dry are put into cut flower cases with vent holes at the two ends whose opening rate is 8 % to 12 %, forming a precooling unit. When the cases of one precooling unit are stacked, the faces with the openings shall all face the same way; once stacked, the two sides of the precooling unit are secured and no gaps are left between the cases. Flowers precooled in water are put into flower buckets and placed in a tent with holes on the two sides, forming a precooling unit. Once arranged, the two sides of the precooling unit are sealed and no gaps are left at the edges of the tent.

5.4.3.2.2 Operation. The precooling units are stacked symmetrically on the two sides of the precooling fan so that a ventilation tunnel is formed in the middle, and the face of the cases with the vent holes shall face the tunnel. The height of the stacked cases is kept within 1 m and the length within 4 m, and the width of the ventilation tunnel is 0.8 m. The top and the front of the cases and of the tunnel are covered with sealing material.

5.4.3.2.3 Requirements. Forced-air precooling of cut flowers uses variable frequency control equipment to regulate the air speed, so that the air speed at the inlet of the cases or of the water precooling tent is held at about 1.8 m/s. The precooling time shall be fixed from the facilities and equipment, the quantity of flowers to be precooled and their intended use taken together; precooling can usually be completed within 2 h.

5.4.3.3.1 Preparation for vacuum precooling. Flowers for vacuum precooling shall be properly packed in cases and loaded on flower trolleys. The cases are usually hard plastic boxes or corrugated cases with vent holes; the trolleys are usually made of stainless steel and their length, width and height shall be set to suit the dimensions of the vacuum chamber.

5.4.3.3.2 Operation. The flowers are put into baskets, stacked on the trolley and pushed with the trolley into the vacuum chamber; the temperature probe shall be inserted into the flower head, clipped between the petals. The chamber door is sealed as required. The precooling temperature is set and the start button pressed to begin precooling. When one precooling run is over the flowers are taken out and the next cycle is awaited.

5.4.3.3.3 Requirements. At each precooling the weight of flowers handled shall not be below one quarter of the rated precooling weight; after eight to ten precooling operations the water shall be drained.

5.5 Short-term storage

5.5.1.1 Premises. The storage premises shall be well ventilated and shall be clean, tidy and free of pollutants, pests and diseases.

5.5.1.2 Temperature. The storage temperature shall be fixed according to the species. For species of temperate origin such as rose and chrysanthemum the storage temperature is generally 1 degree Celsius to 2 degrees Celsius; for species of subtropical origin such as gladiolus and lisianthus it is 6 degrees Celsius to 8 degrees Celsius; for species of tropical origin such as orchid and anthurium it is 13 degrees Celsius to 15 degrees Celsius. The classification of cut flowers by origin is given for reference in Annex A.

5.5.1.3 Relative humidity. The relative humidity of the cold store shall be held at 80 % to 90 %.

5.5.1.4 Gases. The carbon dioxide concentration in the cold store shall be held within 5 % to 8 %; the ethylene concentration shall be held at 0.1 microlitres per litre to 0.3 microlitres per litre.

5.5.2 Equipment. Before the flowers are stored the control equipment shall be tested and adjusted to make sure it works properly. The refrigeration system of the store shall be switched on before handling begins, so that the store is brought down to the storage temperature set. The variation of the store temperature shall not exceed plus or minus 1 degree Celsius.

5.5.3 Operation. Dry storage with plastic film packaging and a self-generated modified atmosphere is used. After precooling the flowers are put into plastic bags 0.04 mm thick, 100 stems to a bag. For ethylene-sensitive species an ethylene absorbent shall be placed in the bag. Flowers shall be stored separately by species, variety, grade and time of harvest, and suitable working space shall be left between the wall and the packages and between one package and another. The storage time shall be fixed according to the type of flower; generally flowers of temperate origin should be held for no more than five weeks, those of subtropical origin for no more than three weeks and those of tropical origin for no more than two weeks.

5.6 Low-temperature transport

5.6.1.1 Temperature. The transport temperature shall be set according to the species and the distance. For species of temperate origin such as rose and chrysanthemum the temperature should generally be 1 degree Celsius to 3 degrees Celsius over long distances and 3 degrees Celsius to 5 degrees Celsius over short distances; for species of subtropical origin such as gladiolus and lisianthus it should be 7 degrees Celsius to 9 degrees Celsius over long distances and 9 degrees Celsius to 11 degrees Celsius over short distances; for species of tropical origin such as orchid and anthurium it should be 13 degrees Celsius to 15 degrees Celsius over long distances and 15 degrees Celsius to 17 degrees Celsius over short distances. The classification of cut flowers by origin is given for reference in Annex A.

5.6.1.2 Humidity. For every species, the relative humidity of the transport microenvironment is 80 % to 90 %.

5.6.1.3 Vibration. Vibration shall be avoided during transport and should generally be held within 1 g of gravitational acceleration; species with strong vibration tolerance such as carnation and anthurium should be held within 2 g of gravitational acceleration. The vibration tolerance of the various cut flowers is given for reference in Annex A.

5.6.1.4 Gases. The build-up of ethylene in the transport microenvironment shall be avoided. For ethylene-sensitive species such as carnation and orchid the ethylene concentration shall be held within 0.3 microlitres per litre; for ethylene-insensitive species such as chrysanthemum and lily it shall be held at 0.1 microlitres per litre to 0.3 microlitres per litre. The classification of cut flowers by ethylene sensitivity is given for reference in Annex A.

5.6.2 Equipment. The transport equipment includes refrigerated vehicles, air freight containers and sea freight containers. Before transport the environmental monitoring and control equipment shall be adjusted to make sure it works properly. The transport equipment shall be clean, tidy and free of pollutants; it shall be thoroughly swept, freed of insects and disinfected, and shall not contain spores of pathogens or insect pests that would harm the quality of the flowers.

5.6.3 Preparation before transport. Flowers to be carried long distances shall be given the protection they need, so that jolting and other adverse environmental stresses during transport do not cause mechanical damage or damage from high or low temperature. Colour-changing temperature indicator labels may be stuck on cases of cut flowers carried in the cold chain.

5.6.4 Loading and unloading. Before low-temperature transport the flowers shall be cooled in advance according to the temperature each type requires. Flowers of the same type, such as temperate, subtropical or tropical flowers, shall be loaded separately; ethylene-sensitive and ethylene-insensitive species shall be loaded separately. When the flowers are loaded, the bottom layer shall be padded with a cushioning material able to bear a certain load, and the packing containers shall be adequately secured to one another. The cases shall be at least 30 cm below the cold air outlet of the evaporator of the refrigeration system, so that a path is left for the cold air to circulate. Flowers shall be handled gently in transit, and violent vibration, jolting, crushing and rubbing shall be avoided.

6.1 Pretreatment solution stage

6.1.1 Sampling. The requirements on sampling are as follows. Products of the same origin, the same production batch, the same variety and the same specification form one sampling batch. Samples are drawn at random from one inspection batch, the unit being the stem, and the sample size follows Annex E according to the quantity of flowers inspected. The procedure and personnel for drawing (and submitting) samples and for inspection, the requirements on the environment and on the inspection body, the rules of judgement, the reporting of results and the issue of certificates follow NY/T 1656.1. The batch size, the sampling method, the sampling frequency, the sample quantity, the sealing, the carriage and the keeping of samples for packed and for loose products follow NY/T 1656.2.

6.1.2 Testing of the active ingredients. A gas chromatograph mass spectrometer may be used to test the content of the active ingredients in the flowers and to judge whether they reach the required level. If the pass rate of the active ingredient indicators is not less than 90 %, the treatment of the batch with the pretreatment solution is judged to conform.

6.1.3 Testing of the effect of the treatment. Vase observation is carried out at 23 degrees Celsius to 25 degrees Celsius to check whether the treatment with the pretreatment solution has reached the vase life set. If the pass rate of the indicator is not less than 90 %, the treatment of the batch with the pretreatment solution is judged to conform.

6.2 Quality grading stage

6.2.1 Sampling. The requirements on sampling follow 6.1.1.

6.2.2 Judgement of the sample. Flowers found not to meet the quality standard, or stacked in the wrong grade, are recorded as a failure of the grading operation. The pass rate of the samples tested in each batch shall be not less than 95 %.

6.3 Bundling and packing stage

6.3.1 Sampling. The requirements on sampling follow 6.1.1.

6.3.2 Testing. The firmness, the evenness and consistency, the appearance and the degree of damage to the flowers of the bundling and packing are tested.

6.3.3 Judgement of the sample. If the pass rate of the samples examined for firmness, evenness and consistency, appearance and degree of damage to the flowers is not less than 90 %, the packing of the batch is judged to conform.

6.4 Rapid precooling stage

6.4.1 Sampling. The requirements on sampling follow 6.1.1; a spot thermometer or a thermal imaging camera may be used to check the uniformity of the precooling and the final precooling temperature.

6.4.2 Uniformity test. The temperature difference between flowers of the same batch shall be within 3 degrees Celsius; the difference in precooled temperature between different parts of one stem shall be within 2 degrees Celsius.

6.4.3 Final temperature test. The deviation between the temperature after precooling and the precooling temperature set shall be within plus or minus 1.5 degrees Celsius.

6.4.4 Judgement of the sample. If the pass rate of the precooling uniformity and final precooling temperature indicators is not less than 90 %, the precooling quality of the batch is judged to conform.

6.5 Short-term storage stage

6.5.1.1 Temperature. During storage the change of temperature in the store is monitored in real time with an automatic temperature recorder, and the change of flower temperature inside the packing bag is checked periodically with a high-precision spot thermometer. The difference between the measured and the set temperature shall be not more than plus or minus 1.5 degrees Celsius.

6.5.1.2 Relative humidity. During storage the change of relative humidity in the store is monitored in real time with an automatic humidity recorder, and the relative humidity set is held at 85 % to 90 %.

6.5.1.3 Gas composition. During storage the carbon dioxide and ethylene concentrations inside the packing bag are checked periodically. The carbon dioxide concentration is determined with an infrared analyser after an hour of warming up and shall be held within 8 %; the ethylene concentration is determined with a gas chromatograph and shall be held at 0.1 microlitres per litre to 0.3 microlitres per litre, the determination of ethylene following Annex F.

6.5.1.4 Monitoring of pests and diseases. During storage the pathogen spores and the insect pests in the cold store are determined periodically. Spores are collected with a spore trap and judged by examination under a microscope; insects are examined by eye where they are visible to the naked eye and with a magnifying glass or a microscope where they are not. The spore concentration and the insect density shall be held within the range at which damage occurs.

6.5.2.1 Respiration intensity. During storage, sampling and testing are carried out, the requirements on sampling following 6.1.1. After the flowers have been held for 6 h at 25 degrees Celsius the recovery of their respiration intensity is determined; if it can return to close to the level before storage, the storage quality of the flowers is judged good.

6.5.2.2 Vase life. During storage, sampling and testing are carried out, the requirements on sampling following 6.1.1. The vase life of the flowers is observed at room temperature; if it can reach 90 % of the vase life before storage, the storage quality of the flowers is judged good.

6.6 Quality testing stage before the product leaves the store

6.6.1 Sampling. The requirements on sampling follow 6.1.1.

6.6.2.1 Testing and evaluation of the specification indicators. The quality of the flowers is tested as laid down in GB/T 18247.1 and the results are evaluated according to Annex G.

6.6.2.2 Testing of the pathological and physiological indicators. The presence of pathogens and the degree of damage are tested according to NY/T 1281. The pathogen content of the flowers shall be below 100 per millilitre; the respiration rate of the flowers is determined following Annex H and the water potential following Annex I.

6.6.2.3 Evaluation of the pathological and physiological indicators. The fall in the respiration rate of the flowers after rehydration at room temperature shall be within 10 % of the respiration rate before they entered the store. The fall in the water potential of the flowers shall be within 10 % of the water potential before they entered the store. The results of the pathological and physiological tests are evaluated according to Annex G.

6.7 Low-temperature transport stage

An automatic temperature and relative humidity recorder and a vibration intensity monitor shall be fitted in the vehicle carrying the flowers, and the changes in these three quantities shall be monitored automatically. The change of temperature shall be held within plus or minus 1.5 degrees Celsius, the change of relative humidity within 20 %, and the vibration intensity shall be not more than 1 g of gravitational acceleration. On this basis it is judged whether the transport environment meets the requirements.

6.8 Traceability method for postharvest handling and its flow

6.8.1 Basic information. The record covers the type of cut flower, the variety, the grade, information on the growing site and other matters.

6.8.2 Process record. While the procedural instructions of each stage laid down in Clause 5 and Clause 6 are being carried out, the following shall be recorded and kept: the name of the person carrying out the instructions of each stage, the time, the place, the particular operation carried out and other matters.