Method for Assessing Dry Matter in Horticultural Products

Abstract

The invention relates to a rapid method for estimating the dry matter content of a fruit or vegetable. The method comprises drying a sample of the fruit or vegetable on a support and measuring the dry matter content, wherein the whole method can be carried out in less than 2 hours. This compares to the industry standard method for assessing dry matter in horticultural products which typically takes 6-48 hours.

Claims

1-29. (canceled)

30. A method for estimating the dry matter content of a fruit or vegetable, the method comprising the steps a) providing material from the fruit or vegetable, b) homogenising the material, c) applying a portion of the material to a support, d) weighing the support and homogenised material, e) drying the homogenised material, f) weighing the support and dried homogenised material, and g) calculating dry matter content of the homogenised material based on the difference between the weight of the support and homogenised material and the weight of the support and dried homogenised material, wherein the dry matter content of the homogenised material provides the estimate of the dry matter content of the fruit or vegetable.

31. The method according to claim 30, wherein the material is from the part of the fruit or vegetable that is consumed.

32. The method according to claim 30, wherein the fruit or vegetable is a fruit or vegetable for which dry matter is used as indicator of quality, preferably the fruit or vegetable is selected from the group consisting of kiwifruit, apples, pears, mangoes, melons, bananas, avocadoes, tomatoes, onions, potatoes, sweet potatoes and kumara, preferably kiwifruit, mangoes and avocado, more preferably kiwifruit.

33. The method according to claim 30, wherein the material is from the outer pericarp of a fruit and wherein the amount of any non-outer pericarp tissue amounts to less than 20%, more preferably less than 10%, more preferably less than 5%, more preferably less than 2%, more preferably less than 1% w/w of the material.

34. The method according to claim 30, wherein homogenising breaks open cells in the material.

35. The method according to claim 30, wherein homogenising the material comprises forcing the material through a small aperture.

36. The method according to claim 30, wherein homogenising the material comprises crushing the material.

37. The method according to claim 35, wherein the aperture is no more than 5 mm in diameter, more preferably no more than 3 mm, more preferably no more than 1 mm, more preferably no more than 0.7 mm, more preferably no more than 0.5 mm in diameter, more preferably the aperture is about 0.4 mm in diameter.

38. The method according to claim 35, wherein the material is forced through the aperture under pressure.

39. The method according to claim 35, wherein the force is sufficient to break open cells in the material.

40. The method according to claim 30, wherein the portion of homogenised material weighs no more than 10 g, preferably no more than 5 g, more preferably no more than 3 g, more preferably no more than 1 g, more preferably no more than 0.7 g, more preferably no more than 0.5 g, more preferably no more than 0.3 g, more preferably no more than 0.1 g.

41. The method according to claim 30, wherein the support is or comprises at least one piece of absorbent material.

42. The method according to claim 41, wherein the support is or comprises at least two pieces of absorbent material.

43. The method according to claim 41, wherein the absorbent material is or comprises paper.

44. The method according to claim 43, wherein the paper is or comprises cellulosic paper, or is or comprises glass fibre paper.

45. The method according to claim 41, wherein the absorbent material is or comprises polypropylene or polyethylene, preferably polypropylene.

46. The method according to claim 30, wherein the material is dispersed on the support to form a thin film and/or to increase the surface area of the material.

47. The method according claim 30, wherein the homogenised material is dried by the application of at least one of: a) heat, and b) air flow or turbulence.

48. The method according to claim 47, wherein the homogenised material is subjected to a temperature in the range 50 to 250° C., preferably the homogenised material is subjected to a temperature in the range 100 to 200, more preferably in the range 110 to 160, more preferably in the range 120 to 150° C.

49. The method according to claim 47, wherein the heat and/or air flow is applied to both sides of the support.

50. A method for estimating the dry matter content of a fruit or vegetable, the method comprising the steps a) providing material from the fruit or vegetable, b) homogenising the material on a support, c) weighing the support and homogenised material, d) drying the homogenised material, e) weighing the support and dried homogenised material, and f) calculating dry matter content of the homogenised material based on the difference between the weight of the support and homogenised material and the weight of the support and dried homogenised material, wherein the dry matter content of the homogenised material provides the estimate of the dry matter content of the fruit or vegetable.

51. The method according to claim 50, wherein the material is from the part of the fruit or vegetable that is consumed.

52. The method according to claim 50, wherein the fruit or vegetable is a fruit or vegetable for which dry matter is used as indicator of quality, preferably the fruit or vegetable is selected from the group consisting of kiwifruit, apples, pears, mangoes, melons, bananas, avocadoes, tomatoes, onions, potatoes, sweet potatoes and kumara, preferably kiwifruit, mangoes and avocado, more preferably kiwifruit.

53. The method according to claim 50, wherein the material is from the outer pericarp of a fruit and wherein the amount of any non-outer pericarp tissue amounts to less than 20%, more preferably less than 10%, more preferably less than 5%, more preferably less than 2%, more preferably less than 1% w/w of the material.

54. The method according to claim 50, wherein homogenising breaks open cells in the material.

55. The method according to claim 50, wherein homogenising the material comprises forcing the material through a small aperture.

56. The method according to claim 50, wherein homogenising the material comprises crushing the material.

57. The method according to claim 55, wherein the aperture is no more than 5 mm in diameter, more preferably no more than 3 mm, more preferably no more than 1 mm, more preferably no more than 0.7 mm, more preferably no more than 0.5 mm in diameter, more preferably the aperture is about 0.4 mm in diameter.

58. The method according to claim 55, wherein the material is forced through the aperture under pressure.

59. The method according to claim 55, wherein the force is sufficient to break open cells in the material.

60. The method according to claim 50, wherein the portion of homogenised material weighs no more than 10 g, preferably no more than 5 g, more preferably no more than 3 g, more preferably no more than 1 g, more preferably no more than 0.7 g, more preferably no more than 0.5 g, more preferably no more than 0.3 g, more preferably no more than 0.1 g.

61. The method according to claim 50, wherein the support is or comprises at least one piece of absorbent material.

62. The method according to claim 61, wherein the support is or comprises at least two pieces of absorbent material.

63. The method according to claim 50, wherein the material is homogenised on a support comprising at least two pieces of absorbent material.

64. The method according to claim 61, wherein the absorbent material is or comprises paper.

65. The method according to claim 64, wherein the paper is or comprises cellulosic paper, or is or comprises glass fibre paper.

66. The method according to claim 61, wherein the absorbent material is or comprises polypropylene or polyethylene, preferably polypropylene.

67. The method according to claim 50, wherein the material is dispersed on the support to form a thin film and/or to increase the surface area of the material.

68. The method according claim 50, wherein the homogenised material is dried by the application of at least one of: a) heat, and b) air flow or turbulence.

69. The method according to claim 68, wherein the homogenised material is subjected to a temperature in the range 50 to 250° C., preferably the homogenised material is subjected to a temperature in the range 100 to 200, more preferably in the range 110 to 160, more preferably in the range 120 to 150° C.

70. The method according to claim 68, wherein the heat and/or air flow is applied to both sides of the support.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0188] The present invention will be better understood with reference to the accompanying non-limiting drawings in which:

[0189] FIG. 1 shows a homogeniser component (plate homogeniser) used for homogenising the material to form a pulp.

[0190] FIG. 2A shows application of the homogenised material (pulp) to a support comprising two circular pieces of glass fibre paper. FIG. 2B shows the material about to be spread on the support by application of moderate force between two Teflon blocks.

[0191] FIG. 3 shows drying components (heat guns) positioned to dry the homogenised material on support comprising two circular pieces of glass fibre paper.

[0192] FIG. 4 shows the change in apparent dry matter DM with heating time.

[0193] FIG. 5 shows the relationship between dry matter (DM) as estimated with the rapid pulp dry matter method of the invention, and dry matter (DM) as calculated with an industry standard Oven Pulp DM method.

[0194] FIG. 6 shows the relationship between dry matter (DM) as estimated with the rapid pulp dry matter method of the invention, and dry matter (DM) as calculated with an industry standard Oven Slice DM method.

[0195] FIGS. 7A and 7B show that the method of the invention appears significantly better than slice DM (the current industry standard method) as a fruit quality indicator.

[0196] FIG. 8 shows the relationship between dry matter (DM) as estimated with the rapid pulp dry matter method of the invention, and dry matter (DM) as calculated with an industry standard Oven Pulp DM method.

[0197] FIG. 9 shows the cartridge support rolled up in an aluminium cylinder.

[0198] FIG. 10 shows the support structure for the three heat guns.

[0199] FIG. 11 shows the relationship between dry matter (DM) as estimated with the rapid pulp dry matter method of the invention, and dry matter (DM) as calculated with an industry standard Oven Pulp DM method.

[0200] FIG. 12 shows the transformation of weight loss during drying into calculated percentage Dry-Matter.

EXAMPLES

[0201] The invention will now be illustrated with reference to the following non-limiting examples.

[0202] It is not the intention to limit the scope of the invention to the below mentioned examples only. As would be appreciated by a skilled person in the art, many variations are possible without departing from the scope of the invention.

Example 1

[0203] The method of the invention is exemplified below using kiwifruit. Those skilled in the art will appreciate that the method can also be performed using other fruit and vegetables.

Summary

[0204] The Gold3 kiwifruit cultivar (Actinidia chinensis var. chinensis ‘Zesy002’) was evaluated for destructive analysis of dry-matter contents.

[0205] The rapid dry-matter measurement method of the invention was compared to the industry standard reference dry-matter measurement (involving 24 hours of drying) to assure that the rapid method of the invention is an accurate and feasible alternative to the industry standard methods.

[0206] The aim was for the rapid dry matter method of the invention to produce dry-matter results which are consistent (linear in relationship) and reproducible with a desirable standard deviation less than 0.2% FW, against equivalent oven dried pulp samples, and less than 0.5% FW against the oven dried slice samples.

Isolation of Outer Pericarp Material

[0207] Kiwifruit outer pericarp was isolated for use in the method of the invention and in the industry standard oven dry matter (Oven DM) method involving 24 hours of drying.

[0208] The skin and seeds were dissected out using a knife and peeler on a chopping board, leaving as much of the outer pericarp as possible.

[0209] The outer pericarp was then cut up into smaller pieces and mixed on the chopping board to assure a homogenous sample.

Homogenisation of the Outer Pericarp—to Produce a Pulp

[0210] A sample of outer pericarp (about 20 g) was placed into a small cylinder 101, of internal diameter 16.00 mm, open at the top end but closed at the bottom with a plate containing a 0.4 mm diameter hole in the middle. This cylinder was placed into the plate homogenizer 103 (termed the ‘pulper’). The plate homogenizer 103 was created in the applicant's workshop according to the requirements of the experiment (FIG. 1).

[0211] High force is provided by a 125 mm diameter pneumatic ram 105 was used to push a 16.00 mm diameter piston 107 down into the cylinder, forcing the outer pericarp tissue through the 0.4 mm diameter hole. The piston with an “O” ring (111N70) secured 2 mm from the front end, preventing material escaping back up the piston, between the piston and the cylinder. The shear forces created in driving the material through the hole are sufficient to cause complete cellular rupture of the kiwifruit tissue and provide a homogenous pulp. The pulp can be received in a receptacle positioned at a location 108 below the cylinder.

Kiwifruit Slice Preparation

[0212] For the standard reference dry-matter method (Oven Slice DM) an equatorial 3 mm slice of the kiwifruit was prepared with the skin and seeds still intact.

Industry Standard (Conventional) Dry-Matter Method for Reference

[0213] For comparison, and to determine the accuracy of the rapid dry-matter method of the invention, industry standard methods for calculating dry matter were performed.

[0214] Both kiwifruit pulp (homogenised material) and kiwifruit slices were used. Generally 1-2 equatorial slices were used per kiwifruit and at least 3 kiwifruit pulp dishes were used per kiwifruit for the reference.

[0215] Both the kiwifruit pulp and slice were used in the same method and is as follows: [0216] 1. Using a maker pen, record the date, fruit sample number and pulp/slice number (if using more than one) on petri dishes. [0217] 2. Weigh the petri dishes on a scale with at least 3 decimal points and record the weights (‘dish wt’) in the excel spread sheet. [0218] 3. Place the pulp (about 4 g)/slice onto the petri dishes then record the weight (‘dish+pulp wt’) again. [0219] 4. Place the petri dishes with kiwifruit sample in an oven set at 65° C. for 24 hours. Make sure to record the time in which the petri dishes were placed in the oven. [0220] 5. Once 24 hours have passed, remove the petri dishes from the oven, allow them to cool for a few minutes, then record the weight (‘dry wt’).

[0221] The dry matter content is calculated by using the following formula;

[00001]$\mathrm{DM}=\frac{100\left(\left(\mathrm{dish}+\mathrm{dry}\mathrm{wt}\right)-\mathrm{dish}\mathrm{wt}\right)}{\left(\left(\mathrm{dish}+\mathrm{wet}\mathrm{wt}\right)-\mathrm{dish}\mathrm{wt}\right)}$

Rapid Dry-Matter Method of the Invention

[0222] The method for the rapid dry-matter experiment using glass fibre paper 201 is as below: [0223] 1. Place a small, closed container (e.g., a plastic petri dish with lid) on the mass balance and zero the balance. This small, closed plastic container is used to contain the GF paper+pulp to prevent the pulp sample changing weight during the weighing process, which may take some seconds. Avoiding exposure to the environment during the weighing process helps to stabilise the weight of the pulp. [0224] 2. Weigh both pieces of glass fibre (GF; Whatman Glass Microfibre Filters GF/A, 70 mm diameter, Cat No 1820-070) paper using a five decimal point weigh scale and record the weight. Use flat nose tweezers to handle the delicate glass fibre paper. [0225] 3. Place the GF paper 201 on a small Teflon block 203a and remove the top paper. [0226] 4. Place about 0.5 g (variation 0.2-1.2 g) of kiwifruit pulp on the GF paper resting on the Teflon block using a small plastic pipette 205 (FIG. 2A) and place the previously removed GF paper 201 on top of the pulp sample. Place another block 203b on top and press firmly together without any rotation (FIG. 2B). [0227] 5. Switch on the BOSCH-PHG 630 DCE, or similar, hot air gun 207 to setting 3 at 150 ° C. The hot air gun 207 will be secure in a retort stand set 4 cm away from the mesh 209 (FIG. 3). It is important to switch on the hot air gun prior 207 to use as it takes time for the hot air gun to heat up to the required temperature. [0228] 6. Place the GF paper+pulp (sandwich) sample inside the small plastic container, on the weight scale, and record the weight. [0229] 7. Carefully pull apart the two GF papers 201 and be careful to assure there are no blobs or ridges of pulp. If there is, rub/rotate the two GF papers together to assure even distribution. [0230] 8. Place each GF paper 201 on the mesh 209, one GF paper under one gun, pulp side up. [0231] 9. Heat both pieces of GF papers using the BOSCH-PHG 630 DCE, or similar, at setting 3, for 2 minutes at 150° C. (FIG. 3). [0232] 10. Place both pieces of paper 201 together again and place inside the small plastic container on the weight scales. Record the weight. The final weight reading needs to happen quickly as the dried pulp will start to absorb moisture from the air which will affect the weight, hence the dry matter content.

Results

[0233] Two minutes heating by the hot air gun system 207 was sufficient to take the pulp sample very close to an asymptotic weight (FIG. 5). The calculated Rapid Pulp DM values were highly correlated with both the values obtained using the Oven Pulp DM method (FIG. 5) and the Oven

[0234] Slice DM method (FIG. 6).

[0235] The correlation with the Oven Pulp DM values was very high (R2=0.99), linear with slope close to 1, a very small average bias (−0.07% FW) and a low root mean square error (rmse)=0.19% FW. This proves the Rapid Pulp DM method is very accurate for measuring expected Oven Pulp DM values.

[0236] The correlation with the Oven Slice DM values was also high (R2=0.92) and the relationship was again very linear with slope close to 1. However the average bias was large (−1.19 % FW) and the root mean square error (rmse)=0.48% FW. The reason there is bias is largely because the outer pericarp, from which the pulp is made, is not representative of the same tissue used with the Oven Slice DM method, which includes the inner pericarp, containing seeds, and the central white core of the fruit. Those two regions have different DM, slightly higher than the outer pericarp. As can be observed, the bias difference is just a fixed offset for the fruit examined here but, because fruit structure is largely genetic, the bias is probably also a constant for a cultivar. The root mean square error (rmse) is probably large due to matters like random fluctuations in seed count, in the inner pericarp tissue of the slice sample.

[0237] The Rapid Pulp DM method of the invention appears significantly better than slice DM (the current industry standard method) as a fruit quality indicator, see FIGS. 7A and 7B. The final soluble solids content (SSC) of a ripe fruit is already known to be a primary indicator of kiwifruit consumer acceptability or taste quality. FIG. 7 shows there is less error or scatter around the regression line for the Rapid Pulp DM data.

Example 2

[0238] The method of the invention is exemplified below using apple, mango, potato, onion and avocado. Those skilled in the art will appreciate that the method can also be performed using other fruit and vegetables.

Summary

[0239] Apple (Malus pumila), mango (Mangifera indica), potato (Solanum tuberosum), onion (Allum cepa) and avocado (Persea americana) were evaluated for destructive analysis of dry-matter contents.

[0240] The rapid dry-matter measurement method of the invention was compared to the industry standard reference dry-matter measurements (involving 24 hours of drying) to assure that the rapid method of the invention is an accurate and feasible alternative to the industry standard methods.

Sample Preparation

[0241] Samples of each fruit or vegetable were prepared for use in the method of the invention and in the industry standard oven dry matter method involving 1 day of drying.

[0242] Each sample was cut up into approximately 5 mm sized pieces. These pieces were pulped according to the method described in Example 1 and approximately 20 g collected into sealed specimen containers prior to the drying procedure.

[0243] For both the rapid dry matter method and the reference method, four subsamples were taken from the pulps for testing.

Industry Standard (Conventional) Dry-Matter Method for Reference

[0244] For comparison, and to determine the accuracy of the rapid dry-matter method of the invention, industry standard methods for calculating dry matter were performed for each sample.

[0245] The pulped samples were thoroughly mixed just prior to sampling from the container. The method was as follows: [0246] 1. Using a maker pen, the date, fruit sample number and pulp (if using more than one) were recorded on petri dishes. [0247] 2. The petri dishes were weighed on a scale with at least 3 decimal points and the weights (‘dish wt’) recorded. [0248] 3. The pulp (approximately 2-5 g) was placed onto the petri dishes then the weight (‘dish+pulp wt’) recorded again. [0249] 4. The petri dishes with the sample were placed in an oven set at 65° C. for 23.5 hours. [0250] 5. Once the incubation period had ended, the petri dishes were removed from the oven, allowed to cool for a few minutes, then the weight (‘dry wt’) recorded.

[0251] The dry matter content was calculated by using the following formula;

[00002]$\mathrm{DM}=\frac{100\left(\left(\mathrm{dish}+\mathrm{dry}\mathrm{wt}\right)-\mathrm{dish}\mathrm{wt}\right)}{\left(\left(\mathrm{dish}+\mathrm{wet}\mathrm{wt}\right)-\mathrm{dish}\mathrm{wt}\right)}$

Rapid Dry-Matter Method of the Invention

[0252] The method for the rapid dry-matter experiment using glass fibre paper is as below. This method was followed for each sample. [0253] 1. Place a small, closed container (e.g., a plastic petri dish with lid) on the mass balance and zero the balance. This small, closed plastic container is used to contain the GF paper+pulp to prevent the pulp sample changing weight during the weighing process, which may take some seconds. Avoiding exposure to the environment during the weighing process helps to stabilise the weight of the pulp. [0254] 2. Weigh a piece of glass fibre (GF; Whatman Glass Microfibre Filters GF/A, 70 mm diameter, Cat No 1820-070) paper using a four decimal point weigh scale and record the weight. Use flat nose tweezers to handle the delicate glass fibre paper. [0255] 3. Place the GF paper on a small Teflon block, positioned so that the paper can be folded in half over the sample. [0256] 4. Mix the sample thoroughly by inversion and/or stirring. [0257] 5. Immediately after mixing, place about 0.3 g of pulp on the GF paper resting on the Teflon block using a small plastic pipette and the fold the GF paper over the pulp sample. Place another block on top and press firmly together without any rotation. [0258] 6. Place the GF paper+pulp (sandwich) sample inside the small plastic container, on the weight scale, and record the weight. [0259] 7. Switch on a pair of BOSCH-PHG 630 DCE, or similar, hot air guns to setting 3 at 150° C. The hot air gun will be secure in a retort stand set 4 cm away from the mesh. It is important to switch on the hot air gun prior to use as it takes time for the hot air gun to heat up to the required temperature. [0260] 8. Fasten each GF paper to the mesh between the two vertically opposed heat guns. [0261] 9. Heat the GF paper using the BOSCH-PHG 630 DCE, or similar, at setting 3, at 150° C. and with maximum flow rate. The heating time was 2.5 minutes from switching the guns on. [0262] 10. Place the GF paper and sample inside the small plastic container on the weight scales. Record the weight. The final weight reading happened quickly as the dried pulp will start to absorb moisture from the air which will affect the weight, hence the dry matter content. [0263] 11. The dry matter was calculated using the following formula:

[00003]$\mathrm{Dry}\mathrm{matter}\%=100\frac{\left(\mathrm{paper}\mathrm{with}\mathrm{dried}\mathrm{sample}-\mathrm{paper}\right)}{\left(\mathrm{paper}\mathrm{with}\mathrm{original}\mathrm{sample}-\mathrm{paper}\right)}$

Results

[0264] The calculated Rapid Pulp DM values were highly correlated with the values obtained using the Oven DM method (Table 1 and FIG. 7).

TABLE-US-00001 Pulp Dry Matter (mean ± stdev; N = 4 reps) Rapid Pulp DM Oven DM Apple 15.97 (±0.09) 16.11 (±0.03) Mango  15.2 (±0.11) 15.73 (±0.07) Potato 13.58 (±0.13) 14.16 (±0.07) Onion  9.23 (±0.09)  9.61 (±0.10) Avocado 30.87 (±0.07) 30.93 (±0.09)

[0265] The correlation with the Oven Pulp DM values was very high (R2=1), linear with slope close to 1, a small average bias (−0.34% FW) and a low root mean square error (rmse)=0.20% FW.

[0266] Table 1 shows the dry matters of the tested fruit and vegetables for the method of the invention compared to oven drying at 65° C. The dry matters are expressed as % by weight of the pulp sample.

TABLE-US-00002 TABLE 1 DM DM Rapid Oven pulp apple 15.9 16.2 16.0 16.1 15.9 16.1 16.1 16.1 mango 15.2 15.7 15.3 15.8 15.1 15.7 15.1 15.8 potato 13.7 14.2 13.4 14.2 13.5 14.2 13.7 14.1 onion 9.1 9.7 9.3 9.6 9.3 9.5 9.2 9.7 avocado 30.8 30.8 30.9 30.9 31.0 30.9 30.8 31.0

[0267] Table 2 shows the average results for each type of fruit or vegetable tested. The average was calculated using 4 samples of each fruit or vegetable. Table 3 shows the standard deviations of results, again using 4 samples of each fruit or vegetable.

TABLE-US-00003 TABLE 2 DM DM Rapid Oven Pulp apple 16.0 16.1 mango 15.2 15.7 potato 13.6 14.2 onion 9.2 9.6 avocado 30.9 30.9

TABLE-US-00004 TABLE 3 DM DM Rapid Oven Pulp apple 0.09 0.03 mango 0.11 0.07 potato 0.13 0.07 onion 0.09 0.10 avocado 0.07 0.09

[0268] This again proves the Rapid Pulp DM method is very accurate for measuring expected Oven Pulp DM values.

Example 3

Summary In an alternative embodiment, the material is homogenised directly on the support.

[0269] The method of the invention is exemplified below using kiwifruit. Those skilled in the art will appreciate that the method can also be performed using other fruit and vegetables.

Isolation of Outer Pericarp Material

[0270] A 10 mm equatorial slice (±1 mm) was cut from a Hayward kiwifruit (Actinidia deliciosa). A 7 mm inside-diameter cork-borer was used to take up to 8 plugs from the slice, between skin and seed-layer. Multiple plugs remained inside the borer to reduce premature moisture loss.

Rapid Dry-Matter Method of the Invention

[0271] Each sample was quickly placed in a pre-weighed cartridge comprising two layers of porous 60 gsm polypropylene “sample retainer” cloth (IndTex, Auckland, New Zealand) formed by heat-sealing the polypropylene into an 85×85 mm pocket, inside an aluminium-foil heat-sealable pouch (CasPak Ltd, Auckland, New Zealand). The purpose of the cartridge was to protect the sample against premature evaporation, sample loss on crushing and during drying, electrostatic effects during weighing, moisture regain between drying and weighing, and the buoyancy errors associated with weighing hot objects.

[0272] The cartridge was weighed by folding the cartridge loosely in two folds parallel to the open end (in thirds), and gently inserting it into the cartridge support on the balance. FIG. 9 shows the cartridge in an aluminium support. The weight of the cartridge was recorded.

[0273] The sample was crushed within the cartridge using a hydraulic press with a force of 4 tonnes borne by the sample. The fibrous component of the sample was reduced to a flake about 0.1 mm thick, and the rest of the sample was spread within the polypropylene pocket, to a diameter of about 60 mm.

[0274] The pocket, containing most of the sample, was removed from the pouch and placed on a pinpoint support midway between two opposed hot-air guns (Bosch PHG 630 DCE) 80 mm apart, set to 120° C. and level-2 air speed.

[0275] The emptied pouch, usually containing a small amount of liquid sample leaked from the cloth during crushing, was placed horizontally over the nozzle of a third hot-air gun set to 100° C. and level 2 air speed. The support structure used for the three heat guns is shown in FIG. 10.

[0276] The pocket and pouch were dried simultaneously for 8 minutes. Drying times of between 2 and 12 minutes were used in drying-completeness testing.

[0277] At the end of the drying period the pocket was promptly returned to the pouch, which was promptly heat sealed to prevent moisture uptake into the dried sample, and then fan-cooled for one minute to avoid buoyancy errors during weighing.

[0278] The pouch was then weighed on a 4-decimal-place recording balance to a stable reading.

[0279] The results were compared to a conventional oven drying method by taking a further seven adjacent plug samples from the same slice, drying them in open petri dishes in a 65° C. oven for 14 hours, and weighing and drying further for a total of 24 hours drying.

Results

[0280] The dry-matter content (DMC) results show that the 8-minute rapid drying method showed sample-to-sample variation with a standard deviation of 0.2% fresh weight units (% FW units). The oven-drying method, using samples from the same slice, showed a slightly larger variation. The mean DMC values from the rapid and oven methods were effectively the same, see FIG. 11.

[0281] The range of DMC value for the rapid method of the invention was from 14.6 to 15.2% FW, Considering the similar or greater range for the oven DMC figures, and the measurement deviation of less than 0.1% FW indicated in FIG. 12 Error! Reference source not found., it is likely that the variability within a single slice is real, perhaps related to small differences in proximity of the sampler to skin and seed regions, and the distribution of cell types within the fruit.

[0282] This again proves the Rapid Pulp DM method is very accurate for measuring expected Oven Pulp DM values.