Center for Food Safety & Applied Nutrition FDA Technical Bulletin Number 5 |
E. METHOD FOR CANNED AND FROZEN FRUITS (V-51)
This method describes a procedure for the examination of canned and frozen fruits to determine.
b. CPG 7110.15 Defect Action Level for Lingonberries
Fruits may be damaged by pre- and post-harvest rots caused by molds and other microorganisms. In addition, insects may attack and damage fruit during growth, harvest, transport, and storage. Such types of damage, as well as the presence of extraneous matter, may occur in the finished product if the raw fruit is not properly prepared and processed under sanitary conditions.
b. Classification of Insect-Damaged and Moldy Fruit -- Classify damaged fruit as follows:
(ii) Moldy or Decomposed -- Any fruit or piece of fruit exhibiting mold on one-fourth (1/4) of the inner or outer surface of the fruit or any fruit affected by mold over an aggregate area greater than the area of a circle 12 mm in diameter.
c. Visual Examination for Insect and Mold Damage -- Examine each individual fruit unit (whole, half, slice, or piece) under good lighting for evidence of damage by insects or molds. Classify according to categories in (4) b. As appropriate, count or weigh reject fruit and passable fruit. Drain and rinse with water on suitable size sieve, collecting rinse water with packing medium for further examination for extraneous matter.
d. Microscopic Examination for Extraneous Matter -- Filter packing medium and rinse water. If filtration is slow or too much debris is present for microscopic examination, transfer to one or more 2 L trap flasks. Extract as in AOAC 970.66B(a), using water and 35 L heptane [III.(7)]. Examine filter papers microscopically and classify extraneous matter according to applicable categories in AOAC 970.66(B)(i).
e. Report -- Tabulate percent of insect-damaged and mold-damaged fruit by count or weight, as appropriate. Report extraneous matter as numbers per unit weight of container or subsample.
F. METHOD FOR DRIED FRUITS (V-53)
This method provides a procedure for sample preparation and visual examination of various kinds of dried fruits to determine the percent of reject fruit damaged by insects, molds, and other causes. The method is applicable, but not limited to, fruits prepared in the following ways:
Defects in dried fruits are generally due to insect damage or mold and fungal decay. In some instances, dried fruits have been found contaminated by sand and soil particles and animal filth. Since the sources of the most likely defects vary with the type of fruit, this section discusses major defects for each fruit separately.
b. Apricots -- The plum curculio [Conotrachelus nenuphar (Herbst)] may damage the fruit by egg laying and by both adult and larval feeding. Larvae of the oriental fruit moth [Grapholita molesta (Busck)] and peach twig borer (Anarsia lineatella Zeller) feed on and damage the fruit. Dried or drying apricots have been found to be commonly infested with Indianmeal moth [Plodia interpunctella (HØbner)], almond moth [Cadra cautella (Walker)] and Australian spider beetle (Ptinus ocellus Brown).
c. Dates -- While on the tree, dates may be attacked by two scale insects, the parlatoria date scale [Parlatoria blanchardi (Targioni-Tozzetti)] and the red date scale (Phoenicococcus marlatti Cockerell) and less commonly by ants and grasshoppers. After drying and packaging, dates may be attacked by Indianmeal moth [Plodia interpunctella (HØbner)], almond moth [Cadra cautella (Walker)], driedfruit beetle [Carpophilus hemipterus (L.)], corn sap beetle [Carpophilus dimidiatus (Fabricius)], sawtoothed grain beetle [Oryzaephilus surinamensis (L.)], and navel orangeworm [Amyelois transitella (Walker)]. The presence of feathers or feces indicates contamination by birds or rodents. Rain may cause dates to ferment on the tree, leading to a condition called souring.
d. Figs -- Numerous insects and several mites attack figs in the green, ripe, and dried stages. Yeasts, fungi, and bacteria also attack figs. Endosepsis is a condition brought about by infection with the fungus Fusarium moniliforme (Sheld.) which is transmitted by the fig wasp. An endoseptic fig has a "wet dog" odor, and its pulp looks dark and dull. Several species of fungi produce "smutty" figs. Another disease of figs is commonly termed souring. It is due to enzymatic fermentation of sugars in the ripened fig by yeasts, fungi, or bacteria. Sourness is identified organoleptically. Figs may also be contaminated with soil, stones, or rodent or bird excrement.
e. Peaches and nectarines -- Insects which attack the fruit while still on the tree include plum curculio [Conotrachelus nenuphar (Herbst)], oriental fruit moth [Grapholita molesta (Busck)], tarnished plant bug [Lygus lineolaris (Palisot de Beauvois)] and others. Drying or dried fruit may be attacked by the nitidulid beetle [Haptoncus luteolus (Erichson)], navel orangeworm [Amyelois transitella (Walker)], raisin moth [Cadra figulilella (Gregson)], or Indianmeal moth [Plodia interpunctella (HØbner)]. Peaches and nectarines are also susceptible to black spot or scab, caused by Cladosporium carpophilum, frosty mildew, due to infection with Mycosphaerella persica, and brown rot, caused by Monilinia fructicola (Wint.) Honey, which enters through feeding punctures of curculio.
f. Pears -- During growth, pears may be damaged by the apple maggot [Rhagoletis pomonella (Walsh)] and by species of thrips, psylla, moths, and curculios. The dried fruit may be attacked by several beetles and by Indianmeal moth [Plodia interpunctella (HØbner)]. Diseases include blue mold rot, caused by Penicillium spp.; brown rot, caused by Monilinia fructicola (Wint.) Honey; bull's-eye rot, due to Neofabraea spp.; core breakdown (internal breakdown, core rot, brown heart), and gray mold rot, caused by Botrytis spp., one of the most serious storage diseases.
g. Prunes -- Plums may be attacked on the tree by the oriental fruit moth [Grapholita molesta (Busck)], lesser appleworm [(Grapholita prunivora (Walsh)], several species of aphids, plum curculio [Conotrachelus nenuphar (Herbst) and a leaffooted bug [Leptoglossus phyllopus (L.)]. In storage, prunes may be damaged by driedfruit moth (Vitula edmandsae serratilineella Ragonot), the navel orangeworm [Amyelois transitella (Walker)], raisin moth [Cadra figulilella (Gregson)], dried prune moth [Aphomia gularis (Zeller)], sawtoothed grain beetle [Oryzaephilus surinamensis (L.)], and merchant grain beetle [Oryzaephilus mercator (Fauvel)]. While drying, rotten or overripe fruit may contain dried fruit beetle [Carpophilus hemipterus (L.)], corn sap beetle [Carpophilus dimidiatus (Fabricius)], or yellow nitidulid [Haptoncus luteolus (Erichson)]. Additionally, the fruit may show evidence of Monilinia fructicola (Wint.) Honey, a brown rot, or Septoria sp., called the shot hole fungus. Several of the insects mentioned above will spread fungi and yeasts in the course of their feeding and breeding activities. Amber or light-colored flesh with a solid texture is one of the characteristics of quality. Texture may vary from solid to the extreme of porosity in which one or more large air pockets occur (bloaters).
Orchard infestation results from the attack of insects before the fruit is harvested and dried. Such attack may be evident as tunnels, pockets of gum in stone fruits, discoloration where feeding has occurred and pronounced damage in the pit cavity of some fruits.
Storage infestation results from insects attacking the fruit during and after drying. Storage pests may contaminate the fruit by the presence of whole insects, cast skins, webbing, and excreta that are not dried down into the fruit. Tunnels or insect-chewed pockets with adhering insect matter may be readily visible on the surface of the dried fruit.
(ii) Mite-damaged -- Any fruit showing obvious presence of mites. Mites may be detected by the dusty, sugary, or encrusted appearance of the dried fruit, by the presence of their dirty white, glistening, or dull-appearing bodies and sometimes by the movement of living mites in the sample when a widespread infestation of the sample has occurred. Confirm suspected mites microscopically and identify if possible.
(iii) Moldy or decomposed -- Any fig-bearing mold over an area that exceeds a circle 5 mm in diameter, or any fig with a sour odor or flavor or darkening and internal rot indicative of endosepsis. Classify any other dried fruit or prune as moldy or decomposed when 1/4 of the fruit is affected or the aggregate affected area is greater than 1 cm2.
Brown rot of stone fruits appears as a central decayed spot surrounded by concentric rings and pustule-like elevations. The spores, in chains, have a characteristic barrel shape. Bin mold, caused by the fungus Geotrichum candidum (Link) occurs as a white filamentous growth over the surface of prunes. Other types of moldy or decomposed areas may be accompanied by a sour or fermented odor.
(iv) Dirty -- Any dried fruit with an appreciable amount of sand, soil, cinders, etc. When a smear of fine dirt particles is the criterion, it should cover 1/4 of the fruit area or an area greater than 1 cm2. Fruit contaminated by larger individual dirt particles, especially those that would be detected upon chewing, should be classified as "dirty" even when the affected area is less than the requirement for fine particles.
(v) Otherwise unfit -- Any dried fruit that is so immature, grossly fibrous or woody that it is valueless for food purposes. Do not classify fruit under this heading that is simply tough or of a somewhat undesirable quality.
b. Sequential Analysis Plan for Dates [Editor's Note: The following table has been revised from the original to reflect current policy found in CPG 550.300]
Number of Dates Examineda |
Accept (at or below) |
Number of Defective Dates | |
Continue Analysis | Reject at or above | ||
100 | 1 | 2-7 | 8 |
200 | 5 | 6-12 | 13 |
300 | 10 | 11-17 | 18 |
400 | 14 | 15-21 | 22 |
500 | 18 | 19-25 | 26 |
600 | 23 | 24-30 | 31 |
700 | 27 | 28-34 | 35 |
800 | 34 | --- | 35 |
c. Sample Preparation and Visual Examination -- Classify all fruits according to (4)a.
(ii) Figs -- Analyze six subsamples of 100 fruits each. Open each fig by inserting a knife into the eye, splitting down the sides, and pulling apart. Examine with magnifier as necessary. Confirm doubtful areas microscopically. Do not classify fruit with fig wasps as rejects.
(iii) Prunes -- Examine a minimum of ten subsamples. Place prunes in large white enamel pan, or in white enameled muffin pan, and add sufficient water to cover fruit. If muffin pans are used, place one fruit in each depression; if flat pans are used, arrange fruits so that they are sufficiently far apart that residues from adjacent fruits will not become mixed. Soak overnight and examine for defects with magnifier, confirming doubtful areas microscopically. For pits in pitted prunes, examine a minimum of 50 prunes from each of ten subsamples from each code, or from the lot if no codes are present.
(iv) Raisins -- Use the method described in Section 9.M.
(v) Other fruits -- Analyze six subsamples of 100 fruits each. Cut each fruit open. Use a magnifier and confirm doubtful areas microscopically.
d. Report -- In reporting results, if a piece falls into more than one reject classification, classify it under the heading first listed in the table. Explain, by footnote to a particular subsample number or by generalization as to the whole sample, the condition of the rejects so that the reviewing officer will have a word picture of the condition of the sample as seen by the analyst.
Tabulate results as follows:
Product Subsample No. | |||||
1 | 2 | 3 | etc. | Average | |
Number Examined | |||||
Insect Infested (Orchard) | |||||
Insect Infested (Storage) | |||||
Moldy or Decomposed | |||||
Dirty | |||||
Otherwise Unfit | |||||
Prunes Only Number of prunes with whole pitsa Number of prunes with pit fragments 2 mma |
|||||
No. of Units Showing Mitesb | |||||
Total No. Rejects | |||||
Total % Rejects | |||||
Remarks: |
|||||
Notes: a Report dimensions in mm b Describe condition of entire subsample |
Simmons, P. and H. D. Nelson, Insects on Dried Fruits, USDA
Agricultural Research Service, Handbook 464, Washington, DC, 1975.
Table of
contents
G. METHOD FOR GRAPE PRODUCTS (V-59)
This method describes a macroscopic procedure for the determination
of insect damage in stemmed and crushed grapes destined for further processing
into grape juice, grape pulp for jam or production of wine. The macroscopic
procedure is particularly applicable to damage by the grape berry moth.
Also included with this method are two microscopic procedures. Determination
of rot in the crushed grapes or in the grape pulp requires a microscopic,
mold mycelia count procedure. Determination of extraneous filth in these
semi-processed products may also require a microscopic procedure utilizing
a flotation recovery technique.
b. Moldiness and Fungal Deterioration -- Rot due to molds may develop before or after harvesting.
c. Extraneous Filth -- Grape products may be contaminated by extraneous matter such as insect or rodent excreta.
b. Visual Examination -- Examine grape material in good lighting; remove insect-damaged grape material and weigh; remove insects and identify.
c. Report -- Report percent by weight of insect-damaged grape material. Also report number, size, and identity of insects found.
b. Analysis -- Make mold count on the undiluted grape pulp of each subsample as in AOAC 965.41.
Measure each subsample up to 1 L and transfer to a 2 L trap flask, AOAC 945.75B(h)(4). Extract as in AOAC 970.66B(b), using water and 35 mL heptane, III. 7. Examine filter papers and report extraneous matter as numbers per unit weight of container or subsample.
b. Mold Count -- Make mold count as in AOAC 984.29.
H. METHODS FOR JAMS, PRESERVES, AND JELLIES(V-61)
Jams, preserves and jellies contain varying amounts of fruit tissues in the product. Visible decomposition or filth in the fruit is generally altered by the processing; thus, more indirect microscopic methods are required for evaluation of these defects. Economic violations may include the substitution of apple fruit tissue for the declared fruit or the addition of berry seeds to the declared fruit in the product.
These methods describe procedures applicable to the analysis of jams, preserves, and jellies. These include the following procedures:
b. CPG 7110.13 Defect Action Level for Mold Count of Black Currant Jam
Improper control of raw material and other poor manufacturing practices may result in the presence of mold or insect or rodent filth in the products. Jams and preserves may occasionally be adulterated by the addition of apple or other fruit tissue, which can be detected microscopically. Also, some samples of preserves have been found to be adulterated by the addition of berry seeds to mask a deficiency in berry pulp.
b. Report -- Report as in AOAC 984.29.
b. Report -- Report as in AOAC 984.29.
Use AOAC 950.89 for light filth, (a) for jam or preserves and (b) for jelly.
b. Visual Examination -- Examine each dish, using a widefield microscope. Apple skin tissue is detected by the presence of tightly rolled bits of tissue. Examination of this tissue under the compound microscope shows quadrilateral cells in window-type grouping. Apple pulp cells usually can be identified by large sac-shaped cells loosely grouped together in small masses. This procedure can also be used for the detection of other undeclared fruit tissues. Refer to the data on microscopic structure and diagnostic characteristics of suspected adulterants as described in Winton's Structure and Composition of Foods, and compare with microscopic examination of authentic specimens.
c. Report -- Report any foreign plant tissue that is present as an apparently undeclared ingredient. Identify if possible. Estimate percent of foreign tissues by microscopic comparison with mixtures containing known percentages of authentic ingredients.
b. Report -- Report total number of seeds, number of covered seeds, and number and percent of "naked" seeds.
Winton, A. L., and K. B. Winton, "Vegetables, Legumes and Fruits," Structure and Composition of Foods, Vol. 2, John Wiley and Sons Inc., NY, 1935.
I. METHOD FOR LINGONBERRIES (V-64)
This method is designed to recover moth larvae (caterpillars) from lingonberries by a flotation procedure. The method is applicable to the canned and frozen product consisting of essentially whole or comminuted fruit. The lingonberry (Vaccinium vitis-idaea L.), also called mountain cranberry and cowberry, grows in northern regions of the Eastern and Western hemisphere. It resembles a cranberry.
Lingonberries may be infested with maggots and moth larvae. Maggots are determined by AOAC 945.78, a microscopic sedimentation procedure. Moth larvae float and require a different procedure. Some of these larvae are external, floating free in the juice or clinging to the outside of the berry. Others are internal and not readily apparent.
b. Visual Examination and Pick Out -- Remove the material from the No. 40 sieve into a white pan and examine under good lighting. Pick out insect larvae and other insect matter. Boil the berries retained by the No. 6 sieve for about 20 min, cool, and mash through the No. 6 sieve. Mix the mashed material with saturated salt solution in a large container. Stir several times and pick out the floating larvae and other insect matter.
c. Report -- Tabulate results as follows:
Code No. ______ | Subsample No. | ||||
1 | 2 | 3 | etc. | Average | |
External Larvae (from material on #40 sieve) Cast skins with heads Larvae |
|||||
Internal larvae (from the #6 sieve) Cast skins with heads Larvae |
|||||
Other insectsa | |||||
Remarks: |
|||||
Notes: a Report identity under remarks |
J. METHOD FOR MINCEMEAT (V-66)
This method describes a microscopic procedure to determine insect matter, rodent hairs, and other extraneous material in mincemeat by flotation recovery. Mincemeat is a mixture of finely chopped fruits, spices, and other ingredients combined in varying proportions; meat and suet may or may not be components.
Mincemeat may be contaminated with filth consisting of insects, insect fragments, rodent hairs, and other extraneous matter. These defects may be present in the various raw materials used to produce mincemeat or they may be introduced during manufacture due to insanitary plant conditions.
b. Report - Tabulate results according to format and applicable categories in AOAC 970.66B(i).
K. METHOD FOR OLIVES (V-67)
This method includes procedures for sample preparation and visual examination of olives to determine the percent of reject olives due to fungal (mold) decomposition, insects, or the presence of pits and/or pit fragments.
Olives, the fruit of Olea europaea L., contain a bitter glycoside which must be removed to make them edible. Many processing methods are used locally in olive growing regions, but there are three major commercial methods:
b. Moldiness and Fungal Decay -- Molds may attack the fruit in the orchard, during transit and storage, and during processing, but they have not been a serious problem with most trade-type olives. Salt-cured olives have the potential to develop a mold problem if the salt treatment is not conducted properly. An anthracnose-type infection (Melanconiales) sometimes occurs, showing characteristic skin lesions in the form of pustules.
c. Pit Fragments -- Pit fragments may be found in pitted olives or in salad olives (olive pieces).
b. Examination for Presence of External Rot -- External rot will appear under water as light-brown or tan colored areas, soft or mushy areas, areas having cracked and broken skins, or areas having small black pustules (fruiting bodies of anthracnose fungus). Where one or more of the above conditions are observed, examine the internal tissue from the questionable area by removing a small portion with tweezers. Place on a slide in a drop of water. Remove another piece of internal tissue from a point opposite the questionable area on the other side of the olive. Place this piece of the olive on the same slide in another drop of water. Examine both portions at 100-200X and classify olives according to the extent of mold damage listed in (4)d.
c. Examination for Presence of Internal Rot -- Examine remaining olives by making a slice in cross-section through of the olive at its midpoint. Pull one side of the section away from the cut and, with a razor blade, make as thin a slice as possible of a cross-section through the epidermis and underlying tissues. Place this section in a drop of water on a slide. Turn the olive over and make a similar slice on the side opposite the first cut. Mount in another drop of water adjacent to the first one, on the same slide. Macerate olive tissues and place cover slips over sections. Examine both portions microscopically at 100-200X and classify olives according to the extent of mold damage listed in (4)d.
d. Classification of Mold Damage -- Classify mold damage as follows:
(ii) 1/4-1/2 of the olive affected -- if mold filaments are widely scattered in one cross-section or portion
(iii) the olive or more affected -- if both cross-sections or portions of the olive contain widely scattered mold filaments.
e. Report -- Tabulate results as follows:
Subsample No. | ||||
1 | 2 | etc. | ||
Number of olives with external decomposition affecting: | Less than 1/4 of the olive | |||
1/4 - 1/2 | ||||
1/2 or over | ||||
Number of olives with internal decomposition affecting: | Less than 1/4 of the olive | |||
1/4 - 1/2 | ||||
1/2 or over | ||||
Remarks: |
b. Visual Examination and Classification -- Examine a minimum of 500 olives from each code or from the lot if no codes are present. Examine each olive and classify those with pit fragments or whole pits into the following categories:
(ii) Olive with a pit fragment measuring 2 mm or larger in its longest direction
(iii) Olive with a whole pit
c. Report -- Tabulate results as follows:
Subsample No. | ||||
1 | 2 | etc. | Average | |
No. of olives examined | ||||
No. of olives containing fragments less than 2 mm | ||||
No. of olives containing fragments 2 mm or more | ||||
No. of olives containing whole pits | ||||
Remarks: |
b. Visual Examination and Classification -- Examine entire drained sample including stuffing for pits and pit fragments. Classify according to size of fragments shown in (6)c.
c. Report -- Tabulate results as follows (300 g is equivalent to 100 Manzanilla size olives):
Subsample No. | ||||
1 | 2 | 3 | etc. | |
Wt of olive material examined (g) | ||||
No. of pits or fragments 2 mm 2 mm or more whole |
||||
Average No. Per 300 g |
||||
Remarks: |
b. Classification of Insect Damage -- Classify results of examination as follows:
(ii) Dacus-damaged (tunneling only) -- Any olive showing maggot tunneling affecting an area 1/4 in. or greater average diameter.
(iii) Scale insect-damaged -- Any olive showing 10 or more scale insects.
c. Report -- Tabulate results as follows:
Olive Type: (green olives, black olives, etc.) | Subsample No. | |||
1 | 2 | 3 | etc. | |
No. of olives examined | ||||
wt of olives examined (salad olives only) | ||||
Total no. of "Dacus damaged"
olives No. with tunneling and maggots No. with tunneling only |
||||
Percent by count of "Dacus damaged" olives | ||||
Percent by weight of "Dacus damaged" olives (salad olives only) | ||||
No. of olives that have 10 or more scale insects present on each | ||||
Average percent (by number) of olives with 10 or more scale insects each | ||||
Remarks: |
L. METHOD FOR PINEAPPLE PRODUCTS (V-73)
This method, applicable to various pineapple products, specifies microscopic procedures for determining.
Methods for these determinations in pineapple juice are contained in AOAC. The AOAC methods for pineapple juice have been modified here to apply to various other pineapple products such as sliced, chunk, tidbit, crushed pineapple, and juice concentrate.
The pineapple [Ananas comosus (L.) Merr.] is native to the American tropics but is now grown in all tropical regions. In the commercial canning of pineapples, inedible parts are removed by machine, forming cylinders of the fruit which are hand trimmed, spray-washed and sliced, or cut into other forms. Broken pieces or slices that are too thick or thin are used for crushed pineapple or juice. Shells and trimmings are pressed and used for juice, which may be refined, mixed with syrup, and added to canned pineapple.
b. Moldiness and Fungal Deterioration -- Black rot of pineapples results from infection by the fungus Ceratostomella paradoxa, which enters at the surface of a freshly cut stem or at a bruise on the fruit. Mold from this source may contaminate juice and other pineapple products if the fruit is not properly sorted and trimmed. Canned pineapple products may be contaminated with fragments of Geotrichum mold by unclean factory equipment where the mold grows.
b. Mold Count -- Make mold count of the drained juice as in AOAC 970.75, returning the decanted supernatant liquid to the remaining drained juice, which is saved for (5)a. below.
b. Report -- Classify and tabulate according to applicable categories in AOAC 970.66B(i).
b. Mold Count -- Make mold count of the drained juice as in AOAC 970.75, returning the decanted supernatant liquid to the remaining juice, which is saved for (7)a. below.
b. Report -- Classify and tabulate microscopic and macroscopic findings according to applicable categories in AOAC 970.66B(i).
Make mold count on well mixed sample as is, using AOAC 984.29.
Dilute concentrate with water according to directions on the container and proceed as in AOAC 970.72A.
Dilute concentrate with water according to directions on the container and proceed as in AOAC 970.72B.
M. METHOD FOR RAISINS (V-76)
This method covers procedures for examination of individual raisins to determine
Raisins are the dried fruits from many varieties of the wine grape (Vitis vinifera L.). Certain small seedless raisins are called currants, although they are not related to the bush fruits of the genus Ribes, which are also called currants.
Raisins may be produced by sun-drying or by artificial dehydration. Sometimes an alkaline dip is used before sun-drying to remove the waxy layer and hasten drying. For artificial drying, many different procedures have been used; these may involve a lye dip, a sulfur bleach, or both. After drying, raisin processing includes removal of dirt and debris, removal of stems, washing, dewatering, sorting, and packaging.
In addition to the insects which attack grapes on the vine, numerous insects may infest raisins in storage, including raisin moths [Cadra figulilella (Gregson)], dermestids, Indianmeal moths [Plodia interpunctella (HØbner)], driedfruit beetles [Carpophilus hemipterus (L.)], and sawtoothed grain beetles [Oryzaephilus surinamensis (L.)]. During periods of unfavorable weather, raisins left to dry in the sun may become moldy, and they may be damaged by fermentation, grit, sand, and soil. These defects may affect the edibility of the product.
This procedure is intended for use with raisins where catalase activity has not been destroyed by treatment with lye, oil, or heat.
Count out 100 raisins from each well-mixed subsample and place 10 or 15 at a time in a crystallizing dish. Cover each lot with a fresh solution of 5% hydrogen peroxide and 1% NH4OH. The moldy areas are detected by the presence of copious oxygen bubbles. Place the crystallizing dish over black glazed paper to give greater contrast. Yeasts will also give a reaction with hydrogen peroxide. Do not classify these raisins as rejects. Confirm the presence of mold filaments microscopically. Count as rejects those raisins that show mold on more than 1/4 of the surface area. Report percent of rejects for each subsample and the average percent of rejects. Report the percent of partially moldy raisins (raisins that show mold on less than 1/4 of the surface area) separately.
Count out 100 raisins from a well-mixed sample or subsample. Place them in a 400 mL beaker, cover with water, heat to boiling, and boil about 5 min. Drain off water and place raisins in a white pan. Cover completely with water and examine with an ocular loupe or jeweler's eyepiece with magnification of about 5X. Pick out those raisins that are obviously moldy and any that are suspected of being moldy. Examine the latter microscopically to determine the presence or absence of mold filaments. Report moldy and partially moldy raisins as described above in (4).
Examine entire contents of an 8 oz. retail package (225 g). Raisins from smaller packages of the same lot or code may be combined so that a composite sample can be examined. Place raisins in a white enameled pan where they can be spread out and examined; note presence of any live insects. Confirm identification microscopically. Report number of whole insects (dead or alive) or equivalent and identify. Also report other insect evidence such as excreta, holes in packaging material, etc.
Weigh out 100 g from well-mixed sample or subsample. Cover with water and boil about 5 min. Pour the raisins into a No. 10 sieve and rinse with a fine stream of water, catching all the water. Allow to settle 10-15 min. Decant the upper portion of the water and then filter the residue through an ashless filter paper. Ignite the filter in a tared crucible at about 500 and weigh to determine sand and dirt. Report as mg per 100 g.
U.S. Standards for Grades of Processed Raisins, USDA Food Safety and Quality Service, Fruit and Vegetable Quality Division, Processed Products Branch, Washington, DC, 1978.
N. METHOD FOR PROCESSED STRAWBERRIES (V-78)
This method covers procedures for processed whole or sliced strawberries to determine the percent of strawberries which contain rot due to decomposition by molds and to determine the numbers of insects present in representative samples.
Most modern strawberries belong to the species Fragaria X ananassa Duch., which originated through hybridization of F. virginiana (Duch.) of Eastern North America and F. chiloensis (L.) Duch. of Western North and South America. Other species have also given rise to cultivated varieties. The frozen strawberry industry accounts for most processed strawberries, although some berries are still canned. Strawberries are also processed into preserves, jellies, ice cream flavor bases, fountain syrups, and pie fillings. This method is applicable to whole or sliced strawberries present as such in the latter products.
Strawberries are very susceptible to rot, especially in hot, humid, or rainy weather. Bruises acquired during picking and handling provide favorable sites for the establishment of mold growth. Sand, grit, and insects can contaminate frozen strawberries. Field insects injurious to strawberry plants mainly infest the roots, leaves, and buds. One example is the strawberry bud weevil (Anthonomus signatus Say). Proper plant sanitation practices during processing should control any other insect problems.
b. Macroscopic Separation -- If the composite subsample consists of whole strawberries, use the entire first portion. If it consists of sliced strawberries, use about half of the first portion.
(ii) Classification of Reject Strawberry Material -- Reexamine the questionable strawberry material removed from first pan and classify each strawberry, slice or fragment according to the following categories:
Confirm the presence of decomposed tissue in the questionable berries, as necessary, by examining sections of the berry tissue for mold, using the compound microscope. Strawberry material with rot areas less than 6 mm (minor defects) or unconfirmed as to presence of mold should be returned to the first pan containing berries with no apparent defects.
Drain the berries with no apparent defects or minor defects on a tared No. 8 sieve for 2 min and weigh. Similarly drain and weigh strawberry material in each of the three reject categories.
c. Microscopic Mold Count -- If a mold count of the unseparated composite subsample is required, use the second portion prepared according to (4)a. above and make mold count as in AOAC 952.22. If a mold count of the reject strawberry material prepared in (4)b. (i) or (ii) is desired to evaluate pick-out, prepare pulp as in AOAC 952.22. Mix 50 g pulped material with 50 g stabilizer solution (III. (15)) and make mold count of the mixed preparation.
d. Report -- Tabulate results as follows:
Code No. ______ | Subsample No. | ||||
1 | 2 | 3 | etc. | Average | |
Total wt of drained fruit (g) | |||||
Total rotten fruit (g) Wt Percent |
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Wt of fruit with rot areas 6-12 mm in diameter |
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Wt of fruit with rot areas over 12 mm in diameter |
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Wt of totally rotten fruit | |||||
Percent of mold count | |||||
Remarks: |
Weigh each subsample, thaw if frozen, then drain on No. 8 sieve nested in a No. 140 sieve. Wash berries thoroughly in cold water and transfer to a large white pan. Slice each berry longitudinally and examine for larvae, using magnification, if necessary. Transfer residue on the No. 140 sieve to the pan and examine for larvae. Report the numbers, size, and identity of larvae found in each subsample.
Strawberry Diseases, USDA Bulletin 2140.
Hypertext updated by gcz/ear/dms/dav 2002-JUL-30