इ टरन ट म नक Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. ज न1 क अ+धक र, ज 1 क अ+धक र Mazdoor Kisan Shakti Sangathan The Right to Information, The Right to Live प0र 1 क छ ड न' 5 तरफ Jawaharlal Nehru Step Out From the Old to the New IS 16038 (2012): Green Coffee - Determination of Proportion of Insect-Damaged Beans [FAD 6: Stimulant Foods]! न $ एक न' भ रत क +नम-ण Satyanarayan Gangaram Pitroda Invent a New India Using Knowledge! न एक ऐस खज न > ज कभ च0र य नहB ज सकत ह ह Bhartṛhari Nītiśatakam Knowledge is such a treasure which cannot be stolen
Hkkjrh; ekud gjh dkwiqh dhv-{kfrxzlr chal dk vuqikr Kkr djuk Indian Standard GREEN COFFEE DETERMINATION OF PROPORTION OF INSECT-DAMAGED BEANS ICS 67.140.10 BIS 2012 B U R E A U O F I N D I A N S T A N D A R D S MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 December 2012 Price Group 6
Stimulant Foods Sectional Committee, FAD 6 NATIONAL FOREWORD This Indian Standard which is identical with Green coffee Determination of proportion of insect-damaged beans issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on the recommendation of the Stimulant Foods Sectional Committee and approval of the Food and Agriculture Division Council. The text of ISO Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following: a) Wherever the words International Standard appear referring to this standard, they should be read as Indian Standard. b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practice is to use a point (.) as the decimal marker. In this adopted standard, reference appears to certain International Standards for which Indian Standards also exist. The corresponding Indian Standards which are to be substituted in their respective places are listed below along with their degree of equivalence for the editions indicated: International Standard Corresponding Indian Standard Degree of Equivalence ISO 3509 : 2005 Coffee and coffee products Vocabulary ISO 4072 : 1982 Green coffee in bags Sampling IS 7236 : 1974 Glossary of terms for coffee and its products IS 10814 : 1984 Method of sampling green coffee in bags Technically Equivalent do In reporting the result of a test or analysis made in accordance with this standard, if the final value, observed or calculated is to be rounded off, it shall be done in accordance with IS 2 : 1960 Rules for rounding off numerical values (revised).
INTERNATIONAL STANDARD IS0 16038 6667-1985 : 2012 (E) Indian Standard Green coffee GREEN - Determination COFFEE DETERMINATION of proportion OF of insect-damaged PROPORTION beans OF INSECT-DAMAGED BEANS 0 Introduction From the proportion of insect-damaged beans thus determined The method described in this International Standard is based on experience gained in the inspection of green coffee beans and in the investigation of the most frequent types of damage to the beans and of the insect species responsible for this damage. Visual examination of the external surface of green coffee beans is the only practical way to identify and separate beans which have been attacked by insects; thus, the method described applies only to external damage caused by insects. - estimation of the confidence limits of the true proportion of insect-damaged beans for a given probability - estimation of the probability that the true proportion of insect-damaged beans will not exceed a given value. 5 Apparatus 5.1 Magnifying glass (recommended) 1 Scope and field of application A magnification of beans. of X 5 is suitable for inspection of the surface This International Standard describes the types of damage caused by insects to green coffee beans and specifies a method for the determination of the proportion of insect-damaged beans in a lot of green coffee, together with the statistical use of the result obtained for technical, commercial and arbitration purposes. The method is applicable to green coffee as defined in IS0 3599. 2 References IS0 3509, Coffee and its products - Vocabulary. 5.2 Sample-holder (optional) The use of a sample holder having a given number of cavities, each capable of holding a whole coffee bean, facilitates counting and separation of beans. 6 Sampling See IS0 4072. 7 Damage caused by insects IS0 4072, Green coffee in bags - 3 Definition Sampling. NOTE - Photographs are useful as a means of illustrating damage caused by insects and other types of damage visible on the external surface of the bean. Some photographic illustrations are given in annex A. For the purpose of this International definition applies. Standard, the following insect-damaged bean: A coffee bean damaged externally by insects. 4 Principle Visual examination of the external surface of green coffee beans to identity those which have been damaged by insects Determination of the observed proportion, as a percentage, of insect-damaged beans and, if possible, identification of the species of insect responsible for the damage. 7. I Description A green coffee bean may show a great variety of damage caused by insects, from minor scars on the surface to a considerable number of holes and tunnels. It is usually impossible to distinguish minor damage from damage of mechanical origin and minor breakage. For the purpose of this International Standard, only major damage is considered, i.e. those beans with clearly visible holes which are characteristic of insect damage and which cannot be mistaken for other damage. If a bean shows several signs of damage, it is considered as a single damaged bean. 1
IS0 66674985 (El The two insect species which are most frequently responsible for damaged and infested beans are Hypothenemus (Stephanoderes) hampei (coffee bean borer) and Araecerus fascicula tus ( coffee bean weevil 1. The damage caused by these insects to the external surface of beans is very specific and usually also indicates internal damage. 7.2 Identification of insects causing the damage In addition to assessment of the damage, it is sometimes possible, and useful, to identity the species of insect causing the damage. Damage caused by H. hampei and A. fasciculatus is different in appearance and the type of damage can thus be used to identify the insect responsible. 7.21 Damage caused by H. hampei The damage seen on the bean surface is exit holes, as well as internal cavities. usually from entry and 8.3 Determination Operating under good lighting conditions, and preferably using the magnifying glass (5.1), examine the entire surface of each bean in the test portion for the different types of holes characterizing insect damage. In order to distinguish between a stain or surface defect and a cavity caused by insects, check with a pin to ascertain whether there is really a hole; such a test is particularly useful along the groove of the bean. Count only those beans which show significant penetration as insect-damaged beans. Separate and count the beans which show damage such as that described in 7.21 and 7.22. 9 Expression of results The observed proportion of insect damaged beans, expressed as a percentage, is equal to The holes are small (approximately neatly cut and circular.. There area. H. hampei storage. 0,3 to I,5 mm in diameter), is often a blue-green stain a round the damaged surface only infests coffee beans in the field and not in where ; x loo 7.2.2 Damage caused by A. fascicufatus 10.1 Estimation The visible damage on the bean surface is usually a bored hole, damaged beans larger than that of H. hampei (from 1,O to 3,0 mm in diameter) and not as neatly cut. 10.1.1 General n is the number of insect-damaged beans; N is the number of beans examined. 10 Statistical interpretation of results of true proportion of insect- A. fasciculatus can feed on green coffee beans during storage, if conditions are favourable, producing cavities and other external damage.. 8 Procedure The estimate of the true proportion of insect-damaged beans in the lot is obtained from the observed proportion of insectdamaged beans calculated as described in clause 9. The reliability of the estimate (calculation of confidence limits), for a 90 % probability, is determined by means of figure 1, from the observed proportion of insect-damaged beans and the number of beans examined. 81, Preparation of the test sample Carefully mix the laboratory sample (see homogeneity of laboratory samples). annex B for a test for 10.1.2 Use of figure 1 Find on the abscissa the observed of insect-damaged beans. proportion, as a percen tage, 8.2 Test portion Take at random at least 100 whole green coffee beans from the test sample. During counting, replace every broken bean selected by a whole bean taken at random from the test sample. NOTE - Broken beans will cause errors because a damaged bean may be counted twice or pieces of beans may be counted as whole beans in the total. For this reason, in order to avoid any confusion in the results, the broken beans should be eliminated after being counted and it can be assumed that the proportion of insect-damaged beans subsequently determined on whole beans represents the proportion of insectdamaged beans within the laboratory sample. From this point, draw a vertical line which bisects both curves corresponding to the number of beans examined (interpolate for test portions comprising a number of beans not shown in figure 1). The ordinates at these points of intersection (a for the lower curve and b for the upper curve) indicate the confidence limits corresponding to the observed proportion of insect-damaged beans. It can be stated, with a 90 % probability, that the true proportion of insect-damaged beans within the lot is between a and b. [i.e. Pr (a < p < b) = 0,90, wherep is the true proportion of insect-damaged beans. 1 2
10.1.3 Example From this point, draw a vertical line until it intersects the curve corresponding to the observed proportion, as a percentage, of Data : insect-damaged beans (interpolate between the curves for frac- Number of beans examined: 400 tional values). Observed proportion of insect-damaged beans: 10 % The ordinate corresponding to the point of intersection gives the probability (confidence level) that the true proportion of From figure 1: insect-damaged beans within the lot is lower than a predetera = 7,5 % mined value, the observed proportion of insect-damaged beans b = 12,5 % being known. Thus : Pr (7,5 % < p < 12,5 %I = 030 i.e. with a probability of 90 %, the proportion of insectdamaged beans within the lot is between 7,5 and 12,5 %. 10.1 A Reducing the two-sided confidence interval If it is wished to teed as follows. reduce the two-sided confidence interval, pro- Take a second test portion of at least 200 beans and proceed as described in 8.3 (if the second test portion appears to be different from the first, check the homogeneity of the laboratory sample by the method described in annex B). Add together the numbers of insect-damaged beans from the first and second test portions and the numbers of beans examined in both test portions. 10.2.3 Interpretation of results If the probability obtained is equal to or greater than the critical probability established by specifications, agreements, etc., the lot shall be considered as containing less insect-damaged beans than the critical level. If the probability obtained proceed as follows. is less than the critical probability, Take a second test portion of at least 200 beans and repeat the operations specified in 8.3 (if the second portion appears to be different from the first, check the homogeneity of the laboratory sample by the method specified in annex B). Add together the numbers of damaged beans from the first and second test portions and the numbers of beans examined in both test portions. Calculate the new proportion of insect-damaged beans and proceed as indicated in 10.1.2 to determine the new confidence limits. Calculate the new observed proportion beans and proceed as specified in 10.2.2. of insect-damaged 10.2 Determination of the probability that the true proportion of insect-damaged beans does not exceed a given value 10.2.1 General The probability that the true proportion of insect-damaged beans in a lot does not exceed a given value is obtained from the observed proportion of insect-damaged beans in the test portion (see clause 9 and figures 2 to 6). 10.2.4 Examples Data : Example 1 Example 2 Number of beans examined 400 350 Observed proportion of 9% 5% insect-damaged beans Selected value 10 % 7,5 % From : (refer to (refer to figure 4) figure 5) Probability 73 % 97 % Figures 2 to 6, which are based on the assumption that the distribution is fundamentally binomial, indicate the probability that the true proportion of insect-damaged beans in a lot does not exceed a predetermined value, once the proportion of insect-damaged beans in a sample of n beans is established. Thus : When testing a lot of coffee, a critical probability (confidence level) should be selected to become one of the factors in the decision process. A probability of 90 % is suggested as being appropriate for the use of this method. However, since the method is a general one, other probabilities may be chosen. 11 Test report a) in the case of example 1, there is a 73 % probability that the true proportion of insect-damaged beans in the lot is less than 10 %; b) in the case of example 2, there is a 97 % probability that the true proportion of insect-damaged beans is less than 7,5 %. 10.2.2 Use of figures 2 to 6 Select the figure corresponding which should not be exceeded. to the predetermined value Find on the abscissa the number of beans examined. If more than one test portion was examined, take the number of beans examined as the sum for all the test portions. The test report shall show the method used and the results obtained. It shall also mention any operating details not specified in this international Standard, or regarded as optional, together with details of any incidents likely to have influenced the resurts. The test report shall conta i n all the information the complete identifi cation of the sample. necessary for 3 3
IS0 66674985 (E) / 0 w co - CD - -4 C r\l 7 0 T co : I I i I 1 I I 4 4
Figure 2 - Probability that the observed proportion of insect-damaged beans is from a lot in which the true proportion does not exceed 5 % - (Observed proportion of insect-damaged beans) 80 70 2 60.- > z Ll :&I 5G 100 200 300 400 500 600 Number of beans examined 700 800 900 1000 5
Figure 3 - Probability that the observed proportion of insect-damaged beans is from a lot in which the true proportion does not exceed 7,5 % 6 (Observed proportion of insect-damaged beans) 80 70 s 60 i-j >.- r= % g 50 40 30 _I I_L -------~ - --_ -_- ~- -.- --- -.....-- --- - - - - - I - - -- -.- -- - - - - - - - 8 lo ---- ~--- 20 - _-- - -.-.- -- - -- ~--- -- -_-_- - -_- --_. ---- --- - ~-- -- ---- -- ---- -. --.--- --- - _- 1n 500 600 Number of beans examined
--- -_-I --- ---- _------------ pp-pp---------- ~ --_. -.- - -- ---- _-- - -- - ---- -- ---. - -- _- - --- --- ---. - - - - - --- - ----~- - -..- - -- - Figure 4 - Probability that the observed proportion of insect-damaged beans is from a lot in which the true proportion does not exceed 10 % -- t (Observed proportion of insect-damaged beans) 80 2 ; 50---- - -_-- - --_ ---w---..---pp-- -_I--I ------------ Number of beans examined 7
------- -- - - ---.. --- - -_ ---- ---- --.-----_.-.-- ---- ~- _ --.-.-- -- - ---- --. --- -_-- -- - - -- - - ---- -- -- --_ --- --- - - --- - -.- - - --_ - _I -.- ----. _-.--.._- -.-. --- --~ ---.-.--- - --.-- --.- --- --.. ~ - - --- --~-~- - - - --- --~ --- - _-- 100 LOO 300 400 500 600 700 800 900 1000 - Figure 5 - Probability that the observed proportion of insect-damaged beans is frorn a lot in which the true proportion does not exceed l2,5 % 00 8 (Observed proportion of insect-damaged beans).- - -- --- Number of beans examined
-.-- - -I_. --- Figure 6 - Probability that the observed proportion of insect-damaged beans is from a lot in which the true proportion does not exceed 15 o/o I (Observed proportion of insect-damaged beans) 90 80 - -.- -- --- ---. - -- --- --.--- - ---- --. 70 - --. --_- --- -- -- - - --- _-- -_ --_- ~ - -4 2 cl 60 w >.a z I). - -- - - -- - - - - -_.-- _-- -.- - -- ---- --- - - - -. - ~- -.-- -- ---- -- : 6 50 40 30 - - ~----_ - -_ - -- --- - --.- -- -- ~ - - -. 20 - - --- --- -.-- --- --_ - 10 1 Number of beans examined 9
IS0 66674985 0 Annex Illustrations of damaged beans A A.1 Beans damaged by H. hampei A.2 Beans damaged by A. fascicu/at/s,..::.. : _:.,::...i... 10
ns damaged by causes other than insects ISO 16038 6667 : : 2012 1985 11
IS0 66674985 0 Annex B Test for homogeneity of the laboratory sample The following statistical test can be used to determine whether the hypothesis of laboratory sample homogeneity should be rejected. The test should be applied whenever there is a suspiciously large difference between the observed proportions of insect-damaged beans in the first and second test portions. Let 5, be the observed proportion, as a percentage, of insectdamaged beans in test portion 1, divided by 100; & be the observed proportion, as a percentage, of insectdamaged beans in test portion 2, divided by 100; fi be the sum of the numbers of insect-damaged beans in test portions 1 and 2, divided by the total number of beans examined for test portions 1 and 2; Then *1 be the number of beans examined in test portion 1; n2 be the number of beans examined in test portion 2. Z= 5, - & J$ (1 -j) Wnl + l/*2) For a 90 % significance test, if/z1 > 1,645, the labora tory sample should be considered to be inhomogeneous. For a 95 % significance test, if /ZI > 1,96, the laboratory sample should be considered to be inhomogeneous. If the hypothesis of laboratory sample homogeneity is rejected, a new laboratory sample should be taken from the bulk sample. 12 12
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