International Produce Training

With stone fruit season nearing, a defect you must keep an eye out for is internal discoloration or internal breakdown occuring in nectarines.

Most nectarines can be stored for a week to 10 days at 40° F with little or no deterioration. They can be stored for up to 3 weeks at 31 to 32° F without serious loss of quality. If stored for longer periods, they are subject to internal breakdown, loss of flavor, discoloration of the flesh, surface pitting and decay. Following longer storage periods, the fruit may appear normal, but often develops serious internal breakdown when transferred to ripening temperatures. The first evidence of breakdown is a reddish brown discoloration and a granular texture of the flesh. The discoloration is usually darker near the pit. Later the flesh becomes a darker brown, often with gray-brown water soaked areas extending from around the pit into the flesh. The graininess increases and the affected flesh has a woody or mealy texture, is off-flavored and lacks juiciness. Even in such advanced stages of breakdown, the fruits usually have a normal external appearance.

The nectarine pictured above was imported for Chile.  There were no external symptoms at all, the nectarine was still considered as being firm, and the nectarine was cut randomly.  Always cut crosswise, as pictured to look for evidence of internal defects.  This nectarine  had an off flavor, but was not mealy in texture.  At this stage I would describe the defect as “Internal discoloration” and like internal breakdown, when scored it is always scored against the 6% tolerance for serious damage, a condition defect.

The USDA does have a sampling plan if you encounter internal defects in nectarines.  It reads as follows:

During examination for external defects it may be difficult for inspectors to detect the presence of internal defects. Some fruit must be cut from every sample. The number of specimens cut is discretionary and based on such factors as varietal characteristics (some varieties are more susceptible to internal discoloration than others), growing conditions, time of year, ripeness of fruit and any external characteristics of possible internal defects.

When there are external indications of possible internal defects, such as riper fruit may have internal discoloration; the percentage of internal defects is based upon the entire sample examined. It is not based upon the number of fruit cut. For example, if an inspector examines a 50-count sample of nectarines, and after cutting 10 suspicious specimens finds 1 with an internal defect, the percentage of internal defects is 2%. (1 defective fruit out of the entire sample, 50 fruit in this case.) When it is known or suspected that internal defects are present, but there are no external indications of possible internal defects a random sample shall be used to determine percentages. Select and cut 10 fruit free from external defects from each sample. When any cut sample exceeds the container tolerance the sample should be doubled to 20 fruit. At least one entire container or 100 count should be cut to determine if the application of tolerances have been exceeded. If the lot fails to meet container tolerances after an entire container (or 100 count) has been cut, revert back to the above-mentioned plan of cutting 10 fruit free from external defects.

Simply put, you do not have to cut all of the nectarines in your sample.  The USDA allows a smaller number to be cut (either 10 if 1 one less internal defects are found, or cut 20 nectarines if more than 1 nectarine is found with a scorable internal defect in your first 10 cut sample).

I received a few pictures the other day of a defect you don’t see too often, but I thought it may surprise a few people if they came across it.  Let’s say you receive a load of potatoes and you proceed to make a few exploratory cuts, and you stumble upon this;

Have you ever seen this before?  You may frequently find hollow heart, internal black spot, net necrosis, or even brown center, but Blackheart is not found too often.  This defect may exhibit no real symptoms externally, unless the black heart is in advanced stages and the tuber may feel a bit spongy, or there may be some gray to bluish gray discoloration showing on the surface.

From Agricluture Hanbook Number 479;  Blackheart occurs at any temperature when the supply of oxygen available to internal tissues is used up faster than it can be supplied.  The affected tissue suffocates and turns black.  Conditions causing blackheart can occur in the field when the soil is flooded or soil temperatures are extremely high, in storage when aeration is poor, in transit when tubers are overheated, or in prolonged storage near freezing.

When looking for this defect it is best to cut the tuber lengthwise (as shown on the left, in the image below), as you will be exposing the greatest amount of surface area to find this defect.

The scoring guideline is specific and easy.  If you see it, any amount at all, and you are sure it is blackheart, it is scored as a serious damage defect.  There is no restricted tolerance for serious damage in the U.S. Potato Standard, so the blackheart would be scored as an internal condition defect, against the 7% tolerance for internal defects.

A question came my way the other day, asking “How many insects are allowed on a head of cauliflower?”  Thinking the answer would be cut and dry, I reached for the U.S. Grade Standard for Cauliflower and found the answer, or so I thought.  From the standard, I paraphrase, it reads:

“Score as damage by insects when any feeding injury on the curd is evident, or when the curd is more than slightly infested or the jacket leaves are more than moderately infested with aphids or other insects;” and “Score as serious damage by insects when the curd is more than slightly infested or the jacket leaves badly infested with aphids or other insects, or when insect feeding injury seriously detracts from the appearance of the head.”

Now let’s dissect this wording into something that is easy (or easier) to understand.

1. If you find any evidence of insect feeding or injury on the curd, score the head as a defect, scored as damage, against the tolerance of 10%; or
2. If you find more than 5 insects on the jacket leaves, score the head as a defect, scored as damage, against the tolerance of 10%; or
3. If you find more than 5 insects on the curds (just the insects, no sign of feeding injury), score the head as a defect, scored as serious damage, against the tolerance of 5%; or
4. If you find more than 15 insects on the jacket leaves, score the head as a defect, scored as serious damage, against the tolerance of 5%.

It looks like the USDA has covered all the basis, but what may seem a bit surprising is the fact that the USDA does not see a problem with a head of cauliflower being infested with 1-5 insects on the curds, meeting the requirement of the U.S. No.1 Grade.  Also, there is no mention of worm injury or worms if found on the head of cauliflower.  We will have to assume if insect feeding injury is a defect, so too would be worm injury.  I would also think finding a worm on the curd itself would be objectionable, thus meeting the definition of “materially affecting the appearance,” so score the head as a defect.

Let me know if you agree with my reasoning, worms and worm injury affecting the curds would both be scored as serious damage defects, against the tolerance of 5%, and worms and worm injury affecting the jacket leaves would both be scored as damage, against the tolerance of 10%.

I am sure everyone has seen traces of black discoloration on sweet peppers.  On jalapenos it seems to be very common, in fact some people actually prefer jalapenos with some black showing on the surface.  But is it a defect?  Does the black discoloration on sweet peppers “materially affect the appearance?”

What would you do if you encountered some green, sweet peppers, but they arrived looking like the peppers in the above image?  I don’t think anyone would disagree that the appearance is definitely affected.  I would bet if these peppers were on display in a store the consumers would select the green sweet peppers first, bypassing the peppers with the black discoloration.

So, I have asked a lot of questions, but what is the answer?  Is the black discoloration a defect for the U.S. No. 1 Grade?  The USDA says “No.”  Let’s look at this a little further.  If a green sweet pepper shows a trace of red, the pepper is scored as a defect, as Turning Red.  If the sweet pepper shows sunburn, affecting more than 15% of the surface, the pepper is scored as a defect.  But if the black color affects a pepper it is never scored as a defect.  What if the black discoloration affected over 50% of the surface of the sweet pepper?  Still not a defect.

The following is taken from the USDA’s Inspection Instructions for Sweet Peppers:

Inspectors may encounter lots and/or loads of peppers with a large number of very dark or black areas, usually starting at the blossom end and covering a considerable portion of the pepper. This is a pigmentation of the pepper and is thought to be a varietal characteristic occurring in some growing areas. These peppers shall not be scored against any of the grades. If the applicant insists on including a description of this factor on the inspection certificate, it shall be reported under “Remarks” in general terms, followed by the word, “not affecting grade,” and “reported at applicant’s request.”

Cut and dry, the black discoloration is never scored as a defect.  I realize the black discoloration does not lead to decay, does not affect the flavor of the pepper, but I am not convinced the black discoloration does not affect the marketability of the sweet peppers.  I’d love to hear your thoughts, should the black discoloration be a defect if the area affected is greater than 15% (scoring guideline for sunburn), 25%, 33%, etc?

Every now and then you come across a defect that you have no idea what it is, or what caused it.  Internal decline in lemons is one of these defects.

This defect occurs in June or July and is evident until September or October, although it has been reported as early as March and as late as November.  Pathologists will refer to this defect as Endoxerosis.  It is a is a common phenomenon in California lemon groves in summer, particularly in the hot inland valleys.  The first sign of endoxerosis in the lemon is formation of cavities adjacent to the vascular bundles in the stylar region (opposite of the stem end) of the peel (Bartholomew, Barrett, and Fawcett, 1923). After formation of the cavities, a colorless, gummy substance is exuded which may clog some of the xylem vessels (Bartholomew, 1928a).

So, what does the USDA say about Internal Decline?

This condition usually occurs at the stylar-end and is frequently accompanied or followed by Alternaria rot. Symptoms of this disease include a breaking down or drying of internal tissue of the stylar end and can be accompanied by a pinkish to brownish gummy mass. Gum formation in the core and in or next to the peel is also common. Any amount is scorable in all grades.

To break this down, the USDA does not say all Internal Decline is decay, but Internal Decline may lead to decay.  If you encounter this defect you will have to cut the lemons is half, either cross-wise or length-wise to examine the fruit.  You may find the core being slightly discolored, and because the USDA says this a “free from defect” you should score the lemon as a defect, Internal Decline.  You are allowed 12% of the lemons with defects, including Internal Decline.  If you find the discoloration is breaking down, the tissue disintegrates when rubbed between your fingers, you should score the lemon as decay.  The U.S. Standards of U.S. No. 1 allow no more than 3% decay.

Bottom line, don’t forget to cut some lemons while inspecting, looking for Internal Decline.  And if you do find Internal Decline be careful to check to see if the disorder is breaking down into decay.

As you inspect green onions you may come across discolored tops, watersoaked tops or even decay.  But you may come come across insect damage, usually seen affecting the tops.

Seen above in this image, this insect damage is caused by a leafminer, insects that feed on leaves of many vegetables.  The adult insect is a winged insect, but the larvae is what causes this damage.  The winding paths or trails are the result of feeding and characteristic of this insect.  Identifying this defect is pretty easy, but determining if the insect damage is severe enough to be scored as a defect is not so easy.

Let’s take a look at the U.S. Grade Standards for Green Onions.  The standard was originally published in 1947, and surprisingly contains the same language today, some 65 years later.  The requirements for U.S. No. 1 state the green onions must be free from damage caused by insects.  That’s it.  Nothing more is mentioned about insect damage, specifically,the amount allowed (scoring guidelines).  The general definition of damage would be applied in this case, meaning if the insect damage is severe enough to materially affect the appearance of the individual onion.

The key point in the scoring definition is “if it materially affects the appearance of the individual onion”, not the appearance of the bunch.  For example, taking a look at the above image you can clearly see the insect damage caused by the leafminer.  You can see the damage on the one onion for sure, and possibly on another onion or two.  If you picked up this bunch of green onions you may not even notice the insect scarring, and  would not even think about it being a defect.  But for green onions you are inspecting the individual onions, not the bunch as a whole.  When inspecting green onions you would separate the onions, counting out 50 individual onions, and pull out any defective onions, such as the one shown above.   If you find three individual onions with insect damage, out of a 50 count sample, you would have 6% damage by insect damage for that sample.

And lastly, how bad must the leafminer injury be to be considered as being materially affecting the appearance?  The USDA does not have any visual aids available or scoring guidelines to follow.   Again, using the above image, the amount of leafminer shown would definitely be a defect.  I would suggest a guideline of “score the green onion as a defect if the aggregate amount of insect damage exceeds an area greater than 3/4 inch in length.”

Have you ever seen cauliflower that appears to have a grainy, or ricey appearance?  Every now and then I am sure will come across this defect.

This defect is called ”Ricey.”  Riciness occurs while growing, due to high temperatures during curd development, and is more prevalent on curds being overmature and from rapid growth, maybe due to excess nitrogen.  The ricey appearance comes from the development of small, white flower buds.

Even though the defect originates in the field and the grower can easily see this defect at the time of shipment, the USDA has classified this defect as a condition defect, insinuating that this defect may not have been visible at time of harvest and developed in transit, or while in storage.  I disagree with their theory, as I have never seen or heard of anyone receiving perfectly good cauliflower, but while in storage for a few days their cauliflower developed riciness.

Some people feel that ricey cauliflower affects the flavor, while others feel it only detracts from the appearance.  Rest assured, that it is safe to consume cauliflower showing riciness, but it may affect your preferred taste.

The USDA does have a specific scoring guideline if you do encounter ricey cauliflower.  Score as damage when the ricey condition has an abnormally rough and granular appearance affecting an area greater than 25% of the surface area of the curd.  This defect is scored against the total defect tolerance of 10%.

In the image above, the ricey area this is visible would be considered abnormally rough and granular in appearance, but without seeing the entire head it is impossible to say whether more than 25% of the surface area is affected.

There are few defects you should always keep an eye out for when inspecting celery; decay, scuffing/bruising and seedstems.  As celery grows normally, the branches originate from the base of the plant.  When seedstems develop the branches have a tendency to grow out of the center, from points above the base.  The growers refer to this growth as ”bolting.”   After harvest the seedstem will not become larger, or more evident, but the celery with seedstems may have a bitter taste.

As seen above, when the seedstem is in advanced stages it is readily visible when performing your inspection.  The USDA does have specific scoring guidelines to follow when  you encounter this defect.  There are 2 ways this defect can be scored as “damage” against the U.S. No. 1 Grade:

1. If the seedstem exceeds 8 inches in length, or;
2. If the seedstem is more than twice the diameter of the stalk

Let’s explain how to interpret the USDA’s scoring guidelines, one at a time.  We will use this image below to illustrate:

If you encounter a seedstem the quickest way to determine if the seedstem is a defect is to simply measure the length of the seedstem.  If you cut the celery in half, lengthwise, the entire seedstem will be exposed.  As shown above, measure the seedstem from the base to the top of the seedstem, exclusive of the leaves.  If the seedstem is longer than 8 inches, it is a defect.  But if the seedstem is less than 8 inches it still might very well be a defect.  You would have to measure the diameter of the stalk, as shown below:

Measure across the widest point of the branches to measure the diameter.  If the length of the seedstem is more than twice the diameter then the stalk of celery is scored as a defect, damage by seedstems.  For example, if the the diameter of the stalk is 3 inches, the seedstem would be considered a defect if the length of the seedstem exceeded 6 inches (3 inch diameter times 2 equals 6 inches).

But what if the diameter you measured was 4.50 inches and the seedstem length was 8.25 inches, would this be a defect?  If you said “yes” you are correct.  Even though the seedstem is not longer than twice the diameter of the stalk (4.50 inches diameter x 2 = 9 inches), it does exceed the first guideline, the seedstem cannot be longer than 8 inches.

Remember, this defect is considered as being a quality defect, meaning it does not progress, or become worse.  If you find seedstems it is to be scored against the lot tolerance of 10% defects.  If the celery is packed for 2 dozen then 2  defective stalks would equal 8%, while 3 defective stalks in a carton would equal 12%, exceeding the lot tolerance for defects.

Every now and then you may see some golden brown to dark brown discoloration affecting strawberries.  You have to remember strawberries are harvested and packed right in the strawberry fields, with the picker also quickly verifying the quality of the berry before placing it in the clamshell.

Although the strawberries are grown on plastic they are still exposed to the sun, as the foliage does not always offer enough protection.  When the sun beats down on the exposed surfaces, the outer cells become damaged.  These damaged cells will later oxidize, becoming a golden brown to dark brown discolored area.  Because the damage may not always be seen in the field, the discoloration may develop after the strawberries have been packed, a condition defect.

As seen above, this is typically what you may find while inspecting strawberries.  The discoloration is found on one side of the strawberry (side exposed to the sun), and near the top, or calyx end of the strawberry.  This can be attributed to sunburn.  But because discoloration may be caused by other factors, the USDA recommends the term “sunburn” not be used if you encounter this defect.  You should describe the defect, call it “discoloration.”

Unfortunately the U.S. Grade Standards for Strawberries and the USDA’s inspection instructions do not offer a scoring guideline, only stating to score the defect when materially affecting the appearance.  Not a whole lot of help.  The USDA does offer a scoring guideline for flattened and discolored bruised areas, scoring as damage when exceeding an area of 1/2 inch on a 1-1/2 inch strawberry.  If we are to use this as a guideline we should be able to utilize the above image (strawberry with discoloration) as a visual aid.  The above image depicts an area of approximately 1/2 inch with a golden brown discoloration.  Any discoloration darker than the discoloration shown above, or with a larger area affected would be scored as a defect.  In other words, the above image is showing the maximum amount of discoloration allowed for a U.S. No. 1 Strawberry.

Please send me your comments, or pictures of strawberries showing various degrees of discoloration.

As many of you know by know, I am always quick to point out ways the USDA could improve their inspection procedures and clear up and misconceptions.  Pineapples and internal breakdown could use some help.  To begin with let’s first explain what internal breakdown is.

As seen above, you can clearly see the discolored flesh of the cut pineapple.  This is classic “Internal Breakdown.”  Unfortunately there are no external symptoms to give you a clue as to which pineapples may have internal discoloration, so you must cut random fruit.  I would suggest you cut the pineapples showing the most yellow color first, or in the firm or ripe stage.  The USDA inspection instructions direct their inspectors to cut the fruit lengthwise, to allow them to seem the most exposed surface area.

But if you have ever witnessed a USDA inspector cutting pineapples you may find them cutting the fruit crosswise.  Are they wrong?  Well technically, yes.  But if you use common sense all experienced inspectors know that the internal breakdown is usually found towards the base.  The following comes from USDA’s own inspection instructions:  “Firm, light brown water soaking of the flesh appears first in the base of the fruitlets near their attachment to the core region an inch or two above the base of the fruit. As it advances, the discoloration tends to move outward and upward until it involves most of the fruit. In most cases there is no external indication of the defect.”  So if they cut the fruit lengthwise may they miss the discolored area near the base?  Maybe.

But the cutting guidelines are not the only thing the USDA should clarify.  The U.S. Standard could use some help too.

I will take this step by step:

1) For U.S. No. 1, all pineapples must be free from Internal Breakdown.  (Free from means present in any amount.  There is no area allowed before scoring a free from defect as a defect.  If you can identify the defect, and the standard states it is “free from” them the specimen is scored as a defect, regardless of the area affected.  For example, decay is a free from defect.  If you have a area of decay 1/32 inch in diameter, or 2 inches in diameter, both spots are scored as decay, as decay is a free from, present in any degree, defect.)

2) If you look up the definition for Internal Breakdown in the U.S. Standard it states: ”Internal breakdown” means a physiological deterioration which results in a watersoaked or brown or blackish discoloration.  The key words are “watersoaked or brown or blackish discoloration, meaning if you cut the pineapple and see a brown discoloration (as see above), then you have found Internal Breakdown.  Also, according to the definition if you cut the pineapple and you see only a watersoaked discoloration then you have found Internal Breakdown.  In other words the Internal Breakdown does not need to show brown or black, only if it is at least watersoaked.

3) If you look further in the U.S. Standard the craziness begins.  Under the Classification of Defects, under the Damage by Internal Breakdown, it now states: “When more than 10 percent of the edible flesh has a light to medium brown discoloration which materially detracts from the appearance or edible quality of the fruit.”  As you can see, now the standard states there must be at least a light to medium brown discoloration present (not just being watersoaked) to score as Internal Breakdown.  AND what happened to “Free From?”  In this section of the standard it now states a specific area allowed for Internal Breakdown before it should be scored a defect.

So what should you do?  Feel free to cut the pineapples anyway you feel will give you the best chance to detect Internal Breakdown.  Personally, I cut the pineapples crosswise, near the base.  Is Internal Breakdown a free from defect or not?  Since the standard does state a specific scoring guideline I would use the guideline, that at least 10% of the edible flesh be affected before scoring as a defect.  Now does Internal Breakdown have to be at least light brown in color?  I guess if you say that watersoaked flesh is the same as being light brown in color, then I think we are talking about the same thing.  Until the USDA develops a visual aid depicting what should be considered as being watersoaked, or light brown, then feel free to use your judgement when scoring this defect.