dimanche 8 juin 2014

20- measuring the quality in the orchard


It is very difficult to measure objectively, if a food tastes good or not.
This will depend on the product itself, and the person who is tasting.
There are a multitude of criteria, measurable or not, which allow characterise the taste.
One can quote for example flavorings, sugar, acidity, astringency, bitterness, firmness, texture, juiciness, the balance between traits.
We must add all elements that will influence the perception of taste, for example, the temperature of the food, or what the person has eaten before, and her state of pleasure during tasting or simply her state of stress or tiredness.

Briefly, to determine whether a product is good or not , the best way is the tasting by experts. In the case of wine, it became a profession. In the food industry, processed products often go through a process of tasting through a consumer panel. But unfortunately, what is accepted as an objective way to describe a wine or a cooked canned dish, is neither recognized nor practiced to describe fresh foods.
Must still report there, that there are several agencies agricultural experimentation, as CTIFL in France, which make commendable efforts in this direction. They allow, for example, characterize a specific variety, describing its typical aroma or flavor.
But they are largely inadequate, given the rapid renewal of varieties of species like peach, and the multiplicity of crop conditions and climatic variations.
And most importantly, they can not respond to the routine problem of agriculture.
Indeed, from one year to another, and even during the same season, the taste of the same food can change, depending on crop or climate conditions. Similarly, a poor irrigation management, or simply abundant rainfalls during harvest can pass a fruit from very good quality at the beginning, to tasteless at the end.

In most cases, in the approach of maturity, sugar and flavorings increase in the fruit, and in parallel, firmness and acidity reduce. This process occurs in the last days before maturity. The color and size can be acquired longer before harvest. Everything depends on the type of fruit and the variety.
It should be added that several species may acquire their final color after harvest, during storage, as is the case, for example, of banana, plum, pear and citrus (process of "degreening").
This is why a fruit picked too far from its maturity, may have good presentation skills (color and size) and conservation (firmness), but will be far from normal gustatory qualities of the variety.
This explains, as I have explained in my post No. 6 "the taste of fresh food," of February 2014, that the taste is much more dependent of harvesting conditions, that from the crop system. We are not able now to distinguish a conventional production from an organic production, from the taste of food, comparing the same variety in equivalent crop and climatic conditions, and identical harvest conditions. Many experiments have been conducted or are underway around the world, and all those that are monitored and analyzed without bias, go in this direction. One of the most active organizations in these actions is the CTIFL (Interprofessional Technical Centre of Fruits and Vegetables), in France.

We therefore use simple means that allow a control of minimum criteria. What can be easily measured?
Sugar and firmness.
Firmness is an easily measurable criterion of progress of maturation for many fruits. It also allows to estimate the life of the fruit after harvest, if the storage conditions are appropriate.
For apple, we can also measure the regression of starch to sugars, a sign of ripeness.
We can also measure the acidity of the juice, but it requires a laboratory manipulation, simple but tedious, not always easy to implement, and difficult to use in routine. This is a quality criterion, not a harvest decision criterion.
Sugar is currently the easiest to measure, with firmness criterion. Thanks to instruments of fast handling, they can be measured directly in the orchard.
These are quality criteria that make a significant help to choose the perfect time to harvest.

Determining the optimal time of harvest is crucial to ensure the highest possible taste quality of the fruit.
Anticipate harvest can give a fruit that has a lot of starch (in the case of the apple), and acid, while having not yet accumulated sugars and flavorings, which can make it unpleasant and even aggressive in tasting.

Instruments which are commonly used in the orchard are the penetrometer for firmness, refractometer for sugar, and the calibrator for the size.

Sugar is measured using the Brix scale (°Bx or ºB), that measures the concentration of a sugar solution. A reading of 10°Bx means there is 10g of sugar in 100g of the solution measured. This is the refractive index RI.
Each type of fruit has its own references. Thus, a sugar level of 7.5 is considered high quality taste for a spring strawberry, but will be considered poor taste for an apple or a peach.

In peach, the standard requires a RI minimum level of 8 for the earliest varieties, but it is generally considered that the quality is satisfactory from 9, good from 10, and high from 12.

Here's a sequence of photos in which I am doing these routine measures in the orchard.

The size, to choose the harvest criteria, and to tell the sales staff what are the characteristics of the fruit.

The firmness, which is measured in the most superficial part of the flesh.

The refractive index (here, a yellow nectarine, very good).

But none of this takes into account the aromas, that can give a good peach with low sugar, or even compensate for a lack of acidity. By against a peach without flavors nor acidity, will be tasteless, even with more than 10ºBrix.
The aromas are currently impossible to measure in routine. It's necessary to choose varieties through tasting.

And for the farmer, there will always be a problem, sometimes serious. This is the plant that makes the taste of the fruit. Genetics is the basis. There are varieties with high gustatory potential (in plum, may be cited the Reine Claude plums, for example), and others with much more limited gustatory potential (many varieties of Japanese plums).
But the weather can play tricks on us, and an overcast weather for several days at the critical moment, may be enough to make the taste fall sharply .
If the fruit is picked too early (that is to say, long time before measurable criteria have reached their ideal potential), then we can come up with a totally tasteless fruit or bad.
But even in very unfavorable conditions, a highly aromatic variety is always better than a little aromatic variety.
It has to be aware that the taste is not a harvest decision criterion. When the fruit is physiologically ready to pick, it must be picked, whether good or not, otherwise you lose it. Flexibility depends largely on the type of crop. In the case of citrus, the margin is quite large. For example, in the case of grapefruit, it is several months. In the case of peach, strawberry, apricot, for example, if one seeks to produce high quality fruit, the margin is one day, sometimes two, never more, and sometimes less than one day.
Adverse weather conditions may cause accelerated maturation of the fruit, without the monitoring criteria have been able to give the warning signal. A heavy and stormy weather can change a fruit from hard to soft in a few hours.
Visual monitoring and forecasting of weather conditions will sometimes be harvest decision criteria.

None of these means can replace the touch and sight. Criteria such as radiance of the color or brightness of the fruit, and the sensation of "gummy" touch that it takes just before losing significantly its firmness, are also taken into account, and for that, the personnal experience is more useful. It is here that I still feel essential...

The main retailing stores, ie supermarkets, have since a long time, chosen to focus on sugar, because it represents for them a simple, cheap and fast way to check whether fruits they buy match their specifications.
On the other hand, they don't seek so much the customer satisfaction, because of the subjectivity and complexity that it represents, but his non-disappointment. The high quality taste of a fruit, is difficult to maintain over time, while a simple criterion of minimum sugar, can not disappoint almost without fail. But it does not absolutely guarantee that the consumer has taken pleasure in eating these fruits.

Yet it is essential to have objective and measurable criteria to assess the quality of the fruit. The system of limiting the determination of the taste, only to the criteria of sugar and firmness, is far from perfect. It is even very inadequate.
Will we be able, one day,  to routinely measure a wider range of quality criteria?
It is likely, but in the meantime, the best for you, consumer, is to ask your local dealer, if he is a specialist , to test, or at least to advise you.
Because there may be a wide variety of tastes and possible sensations while testing an apparently homogeneous product. In the only case of peach, you can have acidulated, balanced or subacid (without acid) , aromatic or not, crunchy or melting, juicy or paste, sweetened or not  fruits.
So, a guidance may be welcome, but is not often easy to find.

You know, when I'm not harvesting peaches, or while on vacation, I am often asked to buy fruit, because I am an expert. Except when I can do it on the market (yet), I find myself in the same situation as you. The fruits are generally all beautiful. But will they be good?
The only thing you can try, but it does not work every time, is to sniff, smell the fruit. If they are aromatic, there are more chances they are good.

Good luck!

I decided to make this post to prepare the next one, about fruit downgraded because of their superior quality.

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