Cal State PPN Glossary of Terms

Antioxidant: Naturally-occurring substances that are known to benefit human health by protecting cells from oxidation. Vitamin C is an antioxidant of which peaches, plums and nectarines are a good source.
Brix: The sugar level of fruit, expressed as a percentage. In stone fruit, brix levels do not change once the fruit has been harvested. Acid levels drop as the fruit ripens and it is the sugar-to-acid ratio that actually determines the perceived sweetness of the fruit.
CA WELL MAT® or California Well Matured®: The California Tree Fruit Agreement maturity standard for peaches, plums and nectarines, California Well Matured® is a registered trademark, owned by the California Tree Fruit Agreement. It is for use only on those fresh California peaches, plums and nectarines which meet the established maturity guidelines for its specific variety, including skin color. California Well Matured fruit is significantly more mature than the U.S.
Chill Hours: The number of hours the temperature is at or below 45° F (7.2° C) during the dormancy period, from the beginning of November to February 15. Measuring chill hours helps growers know how well the trees are resting during dormancy. All peach, plum and nectarine varieties need chill hours. Some need as few as 350, some as many as 900. A total of 800 to 850 chill hours during the dormancy period is the desired minimum.
Clingstone: Varieties of peaches, plums and nectarines that have flesh that adheres, or “clings” to the pit. Most early season peaches and nectarines are clingstone. Late-season nectarines are also generally clingstone, as well as most plum varieties.
Container Markings: Markings on a box or other container of stone fruit that give information about the fruit and packing company.
Dormant: During the winter, peach, plum and nectarine trees become inactive or dormant. Dormancy is like rest for the trees. It begins after the leaves fall from the trees and the weather gets colder. Dormancy ends in the spring when the weather warms and new buds begin to swell and blossom.
Ethylene: A gas released by fruit which helps the ripening process progress.
Flavonoid: Natural pigments that give fruits their bright colors, like the skins of peaches, plums and nectarines. Flavonoids are believed to be beneficial to human health.
Forced-air cooling: A method of cooling fruit after harvest in which very cold air is pulled through fruit in containers.
Freestone: Varieties of peaches, plums and nectarines that have flesh that easily separates from the pit. Most peak-season peaches and nectarines are freestone, as well as most late-season peaches.
Fruitwood: The small branches on the tree on which fruit grows.
Grafting: The process of changing the variety of fruit a tree produces. Fruit trees are made up of two parts, a “rootstock,” which is the roots and trunk of the tree, and the “crown,” the branches that make up the top of the tree. If a grower wants to graft the tree so it will produce a different variety, first, the crown branches are cut back to close to the trunk of the tree. Then, small notches are cut in the branch stumps. A small piece of fruitwood of the new variety, called a scion, is cut to fit into the notch. Once the scions are fit into the notches, the tree’s nutrients will flow into the scion and it will begin to grow into a branch.
Hydro-cooling: A method of cooling fruit after harvest in which fruit is passed through a tunnel of very cold water.
Internal Breakdown: Caused by storing unripened, non-pre-conditioned stone fruit at temperatures between 36°-50°F (2.2°-10°C), internal breakdown results in mealy, brown fruit flesh.

Interspecific Hybrid: A hybrid (cross) of two or more species of prunus fruits. (Prunus fruits include peaches, plums, nectarines, apricots and cherries.) The predominant characteristics of the resulting fruit determine how it will be identified. A combination of plum and apricot with predominantly plum characteristics may be called an interspecific plum. The same combination resulting in fruit with predominantly apricot characteristics may be called an interspecific apricot.
Killing Range: Temperatures between 36°-50°F (2.2°-10°C), which are dangerous to unripened, non-pre-conditioned stone fruit. In the killing range, chilling injury can occur, which can result in the mealiness and flesh browning of internal breakdown.
Peento-type: These unusually-shaped peach and nectarine varieties are flat with a very small seed or pit.
Penetrometer: A pressure-testing device for measuring the firmness of fruit flesh by pushing a pointed probe into the fruit. It measures pressure in pounds per square inch, also known as “pounds of pressure.”
Pluot®: A registered trademark for a line of interspecific plum trees.
Pollination: The transfer of pollen from an anther to a stigma within a blossom so it will be fertilized and may grow into a piece of fruit. Peaches and nectarines are self-pollinating. Plums require pollination by another variety by wind or from bees, either of which can carry pollen from one plum variety to another.
Pre-Conditioning: Also known as conditioning or pre-ripening, a scientifically-based process designed to increase fruit’s market life and reduce its susceptibility to chilling injury, including mealiness and flesh browning, when stored at warehouse cooler temperatures. In pre-conditioning, fruit is cooled to 68°F immediately after harvest and held at that temperature for 36 to 48 hours, then cooled to 34°F to stop the ripening process in preparation for shipping.
Pressure: Fruit flesh firmness in pounds per square inch (PSI) as measured with a pressure tester (penetrometer).
Scion: A small piece of fruitwood used in grafting.
Sub-Acid: Peaches and nectarines that typically have a lower relative acidity level, making them taste more intensely sweet.
Summerwhite®: A registered trademark for white-flesh California peaches and nectarines. Summerwhite® peaches and nectarines have a creamy yellow background color with a pink or red blush and creamy yellow flesh inside. About 25% of California peaches and nectarines are Summerwhite® varieties.
Traceback Marking: Identifies each packed container with a unique number for each packing facility and a date code for the date the fruit was packed. This marking is used by all California packers except those who use a Federal-State Inspection stamp.
Transfer point: The point at which stone fruits are sufficiently ripened to transfer to the point-of-sale or point-of-use, like a retail or restaurant location. For peaches, this is a 6- to 8-pound pressure range, and for plums, a 4- to 5-pound pressure range. This is the range in which stone fruit is least prone to bruising.
Tree ripe: This term may be marked on any container. Individual shippers may have their own standards that define their individual Tree Ripe program. Contact your shipper to learn more about their program.
US MAT or U.S. Mature: The federal minimum maturity standard, which may be applied to fruit that does not meet the higher California Well Matured® standard. This fruit may have container markings that say “US Mature” or “US MAT.”