Canned Plums
June 1977

GENERAL PROCEDURES

The acidity of plums causes pinholing of metal containers. Purple
plums are canned in enamel-lined cans. Other plums are packed

in plain interior cans. Record the kind and condition of the
container. This is important in purple plums because buyers
expect enamel-lined cans.

The FDA Standards of Identity permit nutritive carbohydrate sweeteners,
water, fruit juices either single strength, mixed with water, or

mixed with nutritive carbohydrate sweeteners as packing média. There
are no minimum Brix limits for water and fruit juices. However, make
and record Brix readings for plums packed in water or fruit juices.

If more than one container is used to form the standard sample unit
size, determine the Brix of only one container in each sample unit.

Handle canned plums gently. Do not dump “whole” plums from the
draining sieve onto the grading tray. Remove the plums by hand.
"Halves" may be gently poured from the draining Sieve. Place the
units on the grading tray in rows of equal numbers. It simplifies
the counting of defects. Also record the number of plums in each
container.

QUALITY FACTORS

Similar varietal characteristics.

“Similar varietal characteristics" refer to general varietal color,
size, shape, pit formation, or other identification. It is a
requirement of all grades above Substandard. All plums in’a single
container need not have identital characteristics. Only mixed
varietal types that seriously detract from the overall appearance
are considered as failing the requirement. It's possible to mix
Stanley prune plums and Italian prune plums without failing the
requirement.

Flavor and odor.

Normal flavor and odor is a requirement of all grades above Substandard.
Sample units that fail flavor and odor requirements, but are edible,

are Substandard. Consider them "deviants" and include them with

other quality factors (collectively) in accordance with the "Regulations."
Inedible sample units are “worse-than-a-deviant."


Canned Plums
June 1977

QUALITY FACTORS (CONTINUATION)
Character.

Character refers to the texture and condition of the fruit flesh
in relation to ripeness or maturity. Generally, skin color and
flesh color are indicators of maturity. Plums may be slightly
on the immature side and be of proper ripeness for canning.

Well-matured purple plums should be ripe enough for the pit to
separate from the flesh of the plum. Green-yellow plums do not

have the “freestone" characteristic.

Shriveled areas on plums.

Shriveled areas normally are found on the stem-end of purple
plums. It's caused by sugaring or natural dehydration.
Canning may bring slightly shriveled plums to normal texture.
Tough and leathery shriveled areas are scored as either
"fairly good character" or "poor character," depending on the
severity of shriveling.


Canned Plums
June 1977

QUALITY FACTORS (CONTINUATION)
Uniformity of size.

“Uniformity of size" refers to the variation of the weight among
plums in the standard sample unit. It does not cover shape.
Halved plums are not required to be cut along the suture. Actual
experience in weighing plums makes it unnecessary to weight ail
of the plums in each sample unit. Pick the sample unit which has
the greatest variation of size by visual examination. Determine
compliance of the worst sample unit with limits for the grade
classifications. Other sample units in the sample can be compared
to the results of the worst sample unit. Use a gram scale or a
scale calibrated to the nearest 1/10-ounce. Refer to Inspection
Aids in the general handbook for weight/percentage relationship.

Defects.

Canned plums are rarely peeled or trimmed for canning. Unless
plums are sorted closely prior to canning, insect infestation,
decay, and defects present on the fresh fruit are carried through
to the canned plums. Even with close sorting, defects on purple
plums are difficult to find. Market demand does not require
heavy sorting of purple plums. Many processors attempt

to pack only grade B or grade C plums, unless plums are packed
in glass.

Growth cracks are distinguishable by oxidation along the edge of
the crack or by a scab-like appearance. Brown rot is more prevalent
during seasons of hot, humid weather. Other kinds of defects are:
gummosis, hairmarks, sunburn, sunscald, split pits, russeting,
scars, and bruise.

Deformities not considered as defects.

1. "“Mottling" not associated with defects or any
abnormality;

2. Shriveled plums; or

3. Internal gummosis not associated with any hard,
protruding area on the surface.

rH



Canned Plums
June 1977

QUALITY FACTORS (CONTINUATION)

Color.

Purple plums.

The characteristic color of canned purple plums is a range
of rich-amber-brown to deep-garnet-purple. Color covers the
brightness of the skin, and any exposed flesh. "MottlingTM
of the skin is characteristic. It does not penetrate the
skin.

"Dead-browun" color of purple plums.

"Dead-brown" color means a lifeless, dull, brown color
due to overripeness, immature fruit, or prolonged
storage.

Clearness of packing liquid of purple pluns.

The color and clarity of the packing liquid of purple
plums is indicative of properly ripened and properly
processed plums. It is a related factor in scoring
color. Consider clearness of liquid as follows:

Grade A - The liquid is highly colored and clear.
Slight amounts of flocculent material
may be present.

Grade B - The liquid need not be distinctly purple.
It may be lighter in color and reasonably
clear.

Grade C - No requirement for liquid.

Green-yellow plums.

Consider the intensity of color characteristic of the varietal
group. The color of the liquid is not a scoreable factor

for green-yeliow plums. These plums are frequently packed in
glass.

Canned plums packed in heavier sirups have more luster than those
packed in light sirup, juice, or water. Disregard brightness
created by the sirup in scoring color. Score canned purple plums
immediately after removing from the draining sieve. Exposure to
air causes the color to deteriorate. Green-yellow plums do not
change color rapidly when exposed to air.


Canned Plums
June 1977

QUALITY FACTORS (CONTINUATION)

Defects (continuation).

Harmless extraneous material.

HEM includes leaves, leafy material, and stems (other than
short stems). Count each piece of HEM as one defect, regardless
of size. If two or more leaves are attached to each other as
one unit, count as one defect against HEM. If leaves are
attached to a twig, as one unit, count as one defect against
HEM, If a unit of HEM includes a "small stem", count the unit
as one defect against HEM and ignore the “small stem."

Peel in peeled plums.

Grade A - Allow 1/4 square inch of peel per pound of
total contents (sample average).

Grade B - Allow 1/2-square inch of peel per pound of
total contents (sample average).

Grade C ~ Allow 1 square inch of peel per pound of
total contents (sample average).

Individual sample unit - Allow twice the sample average
requirement for the applicable grade classification.

Brown rot.

Two common decays affect plums: brown rot and rhizopus rot.
“Rhizopus rot" is soft. "Brown rot" is difficult to find on
purple plums.

"Brown rot" appears as dark, circular areas with the center
of the circle broken and star-shaped lesions extending to
the edge of the circle. Include "brown rot" in the allowance
for "seriously blemished" units. See also Branch guidelines
for natural and unavoidable defects in food for human use.

Split skins.

Some plums crack or split during processing. Some tough
skinned varieties do not crack or split. Also some processors
intentionally overcock to cause split skins, and some do not.
Consider broken skins under "character" if the skins crack
and cause the plums to be soft. ‘Do not consider split skins
under defects. 7


USDA] INSTRUCTIONS FOR INSPECTION

of

CANNED PLUMS

For Use of USDA Processed Products Inspectors

UNITED STATES DEPARTMENT OF AGRICULTURE
AGRICULTURAL MARKETING SERVICE

FRUIT AND VEGETABLE DIVISION
PROCESSED PRODUCTS STANDARDIZATION AND INSPECTION BRANCH



Canned Plums
June 1977

QUALITY FACTORS (CONTINUATION)
Defects (continuation).
Gumosis.

Gummosis in fresh plums is a yellow, wax-like substance. In
canned plums it turns reddish or reddish~purple color and
appears as a gelatin-like mass in either the flesh or on the
surface of the plums. Gummosis accumulates between the pit
and the surface, and may force its way through the skin.
When it has broken through the skin, a hard knot similar to
a healed-over insect bite or a gelatin-like mass appears on
the surface.

Internal _gumnosis.

Internal gummosis not associated with a healed-over
break on the skin (hard knot) is not scoreable as
a defect.

External gummosis.

“External gummosis" is as follows:

1. A hard knot or a healed~over break on the
skin. An exuded gelatin-like substance is
or has been present on the surface; or

2. A hard knot or a healed-over break on the
skin. An exuded gelatin-like substance is
not present on the surface, but is present
in the flesh of the plum.

Score “external gummosis" as “blemished” when it materi-
ally affects the appearance of the plum. Do not score

if it slightly affects the appearance of the plum. Score
“external gummosis" as “seriously blemished" when it
seriously affects the appearance and eating quality of
the plum.

Small stem.
A “small stem" is the stem which attaches the plum to the

twig. Score a "small stem" whether found loose in the container
or attached to a plum.


Canned Plums
June 1977

VARIETAL TYPES (CONTINUATION)

Green-yellow group.

Green-yellow plums are light-colored, and sweet but slightly tart.
These varieties fall into two subgroups: green-gage and yellow-egg.
Some varieties of green~yellow plums lose their varietal character-
istics after canning and are marketed interchangeably.

Green-gage plums include such varieties as: Reine Claude, Bavay,
Yellow-gage, Washington, and Jefferson. Yellow-egg plums include
such varieties as: Yellow-egg and Golden Drop.
SAMPLE UNIT

A sample unit is as follows:

1. The entire contents of a container; or

2. A portion of the contents of a container; or

3. A combination of the contents of two or more containers.
The U.S. standards specify a standard sample unit size. Each sample
unit must contain a specified number of plums (25 whole plums or
50 halves). Prior to sampling small-size containers, determine the
approximate count of plums in the container.
When more than one container is required to obtain the sample unit
size, take all of the containers from the same case until the
sample unit size is reached. Mark each container in the sample

unit to retain its identity.

If only one container is required to meet the sample unit size,
take only one container from each case selected for sampling.


Canned Plums
June 1977

GENERAL INFORMATION
Color of the skin and flesh is an indicator of plum maturity.
Purple plums are ripe for canning when the (1) skin is deep-purple
color; and (2) flesh is amber color and separates from the pit.
Immature purple plums have (1) poor character; (2) mushy flesh;
(3) poor separation of flesh and pit; and (4) poor flavor. Over~
ripe plums have (1) brownish, lifeless color; (2) loss of character;
and (3) loose pits.
Plums wrinkle near the stem-end at the beginning of the prune stage.
Plums at the prune stage are too ripe for canning. At the prune
stage, plums (1) process hard; (2) turn “dead-brown" to purple-black
color; (3) wrinkle; and (4) have pits that adhere to the flesh which
often discolors the flesh (pit browning).
Some varieties of high-sugar plums are suitable for drying into prunes.
Any canned fresh plums, but not dried prunes, of the varietal types
mentioned in the U.S. standards are considered “canned plums."

VARIETAL TYPES

Purple plum group.
Italian prune plun.

The Italian prune plum is well adapted to canning. Some of
its characteristics are as follows:

1. Medium size;

2. Long-oval shape with enlarged suture side;

3. Purplish-black color;

4. Thin, slightly tough skin;

5. Yellow, firm, juicy, subacid, slightly aromatic flesh;
6. Freestone; and

7. Pit is sharp pointed.

Stanley prune plum.

The Stanley prune plum is grown principally in Michigan.



PREFACE

These instructions are designed primarily for Processed Fruit
and Vegetable Inspectors of the U.S. Department of Agriculture.
They are not intended to be a comprehensive treatise on the
subject but give background information and guidelines to
assist in the uniform application and interpretation of USDA
grade standards and other similar specifications.

These instructions are revised as necessary without public
notice and no mailing list is maintained as public advisory
of such changes.

The citation of any data, criteria, techniques, illustrations,
copyrighted material, or pictorial representation accredited
to private authorship is used with the permission of the
individuals or sources cited. Unless a specific accreditation
is referenced, the information herein has been compiled and/or
developed from sources available to the public as well as from
technical knowledge of personnel in the Department.

Compliance with the suggested guidelines and other pertinent
information herein does not excuse any one from failure to
comply with the Federal Food, Drug, and Cosmetic Act or any
other applicable Federal or State laws and/or regulations.

Except for official USDA inspection aids or devices and color
guides (or standards) produced under license of the Department,
the mention of any supplier, patented device, product, brand-
name, or equipment does not imply endorsement by the Department
over any other similar, or equally effective, material.

Information contained in this instruction is available to the
public. Inquiries as to availability of portions of this
instruction and copying or reproduction privileges should be
addressed to:

Chief

Processed Products Standardization
and Inspection Branch

Fruit and Vegetable Division, AMS

U.S. Department of Agriculture

Washington, DC 20250