Guide to selection and classification of stone fruit (bone fruit)
What is meant by “stone fruit” and botanical framing
Stone fruit includes all species that contain an inner stone (a woody endocarp enclosing the seed) and are botanically classified as stone fruits. These fruits have three distinct layers: the skin (exocarp), the fleshy flesh (mesocarp) and the stone (endocarp), which is responsible for the typical balance of sweetness, texture and juiciness.
In agronomy, the distinction between stone fruits and pome fruits is fundamental: the former include fruits such as peaches, apricots, cherries, and plums, while the latter-such as apples and pears-do not possess a stone but a core with internal seeds.
The main varieties grown in Italy and classified as stone fruit are:
- Peaches (Prunus persica) – characterized by yellow or white flesh, intended for both fresh consumption and industry.
- Apricots (Prunus armeniaca) – medium-sized fruit with dense, fragrant flesh.
- Cherry tree (Prunus avium, Prunus cerasus) – small, compact drupe, very sensitive to handling.
- Plums (Prunus domestica) – oval fruit with thin skin and excellent shelf life.
- Almond (Prunus dulcis) – belonging to the same botanical family, but considered a dried fruit.
Recognizing this category is essential because the presence of the kernel affects the texture, ripeness, and shelf life of the product. Consequently, post-harvest handling and calibration require dedicated systems that assess weight, size, color, and integrity accurately and consistently.
Stone fruits, because of their internal structure, require dedicated selection technologies that can analyze each fruit without compromising the pulp. Tools such as Rollvy grading machines and Logika solutions now enable the highest levels of precision by integrating multispectral vision, dynamic weighing, and surface quality analysis.
Why proper selection and calibration is important
For a modern fruit and vegetable company, the selection and grading of stone fruit represent strategic steps in defining the commercial quality and market value of the product. Uniform size, controlled ripening, and the absence of visible defects are factors that directly affect consumer perception and the ability to position oneself in foreign markets.
Stone fruits have a delicate behavior: a short harvest window and a strong sensitivity to shocks and stone pressure. For this reason, inadequate sizing can compromise the inner pulp and drastically reduce the shelf-life of the fruit.
Through automated selection facilities, manufacturers can sort lots according to:
- Caliber and weight-to ensure uniformity in packaging;
- Skin and flesh color-direct indicators of ripeness;
- Core integrity-determining criterion for commercial use;
- Physical defects-such as dents or cracks that reduce the class of membership.
Well-designed sorting systems reduce waste, improve traceability, and optimize batch management along the supply chain. Modern fruit and vegetable processing technologies now integrate optical sensors, computer vision algorithms, and statistical analysis software that allow each individual fruit to be classified in real time.
In this way, calibration is no longer just a mechanical process, but becomes a product enhancement step in line with European quality standards and the traceability requirements of distribution chains.
Digital management of calibration parameters, as with Logika solutions, allows each fruit to be associated with its production batch, creating reports and yield analyses that improve future agronomic decisions.
In a context where sustainability and quality are at the center of agricultural policies, proper calibration of stone fruit represents the meeting point between innovation, efficiency and competitiveness. It is the element that allows a supply chain to ensure not only aesthetic uniformity, but also sensory consistency and food safety throughout the journey from field to consumer.
Basic criteria for calibrating stone fruit on the bone
Bone fruit grading is a technical process that allows each fruit to be graded according to measurable parameters, standardizing production and ensuring uniform quality standards.
In processing lines dedicated to stone fruits, there are five main evaluation criteria: size, color, degree of ripeness, core integrity and absence of visible defects.
| Parameter | Technical description | Business impact |
|---|---|---|
| Caliber | Diameter or weight of the fruit, measured by sensors or load cells | Visual uniformity and packaging standards |
| Color | Color analysis of peel and pulp using multispectral cameras | Determinant for the perception of freshness |
| Maturation | Sugar degree (°Brix) and pulp consistency | Defines the destination: fresh consumption or processing |
| Integrity of the core | Checking the internal structure, no cracks or fractures | Safety element and internal quality |
| Physical defects | Injuries, dents, or deformation of the peel | It affects the commercial class and price |
Quality classes and European standards
In line with Regulation (EU) 2023/2429, stone fruit is generally classified into three main categories, defined by uniformity and defect tolerance criteria.
The correct membership of a lot in a quality class provides transparency in markets and avoids commercial disputes.
| Class | Features | Defect tolerance | Destination |
|---|---|---|---|
| Extra | Perfect fruit with no visible defects, homogeneous color and size | ≤ 5% | Premium market, export |
| I Class | Slight defects in shape or coloration, but overall uniform appearance | ≤ 10% | Large-scale distribution |
| II Class | More obvious defects, suitable for consumption or processing | ≤ 15% | Processing industry |
Technologies for calibrating stone fruit.
Automatic selection and sizing lines are the heart of modern fruit and vegetable plants today. Electronic weighing and machine vision systems make it possible to handle large volumes of fruit while ensuring precision and traceability.
Rollvy grading machines use multispectral cameras and artificial intelligence algorithms to analyze each fruit in real time, detecting imperfections or color differences not visible to the human eye. These technologies are distinguished by their ability to integrate visual analysis and automatic weighing, making classification more reliable and faster.
Logika grading machines, on the other hand, offer a modular approach based on dynamic weighing and automatic unloading. With precision sensors with an error of less than 2 grams, they ensure operational continuity even in large plants and significantly reduce line losses.
Both systems share one essential feature: the ability to integrate traceability software that links each fruit to its lot of origin. This makes it possible to analyze production data, calibrate settings according to variety, and optimize processing cycles according to seasonal needs.
For a complete overview of the technological solutions adopted in the sector, see the section on innovations for fruit and vegetables.
Example of variety and average calibration parameters
Each stone fruit has different physical and mechanical characteristics that affect calibration settings during industrial selection. The size, pulp density and shape of the kernel determine the reference values for automatic classification.
The following table shows a generic comparison of some common stone fruit varieties grown in Italy and the United States, with indicative average values used in the main calibration lines.
| Varieties | Origin | Commercial caliber | Average weight (g) | Prevalent destination |
|---|---|---|---|---|
| Peaches “Gialla di Romagna” | Italy | 60-80 mm | 130-170 | Domestic fresh market |
| Cherry “Sweet Heart” | United States | 26-30 mm | 9-13 | Premium export |
| Apricots “Orange Red” | Italy | 40-55 mm | 55-75 | Processing and domestic consumption |
| Plums “Black Amber” | California (USA) | 45-60 mm | 60-80 | U.S. market and export |
| Nectarines “Big Top” | Italy/USA | 65-85 mm | 140-190 | International distribution |
These values represent rough indications: each calibration plant may vary parameters according to variety, ripeness and commercial use.
In general, European productions focus on a more aesthetic and calibrated selection for fresh consumption, while U.S. productions focus on uniformity and mechanical strength for long-distance logistics.
Toward sustainable and smart calibration
Calibrating stone fruit is not just a technical step, but a strategic lever for sustainability. Reducing waste, improving precision, and enhancing the value of each batch means optimizing resources and ensuring a smaller environmental impact.
Sorting systems technologies are evolving toward systems that are increasingly integrated with artificial intelligence and IoT sensing, capable of real-time adaptation to production characteristics.
In this scenario, the combination of solutions such as Rollvy and Logika represents the perfect synthesis of optical precision and operational flexibility.
Investing in smart grading and selection technologies means anticipating market needs and building a more efficient, transparent and sustainable fruit and vegetable supply chain.
The value of precision in the stone fruit supply chain
In an increasingly competitive industry, the adoption of automated systems and analysis software makes it possible to transform calibration into a competitive advantage, capable of differentiating Italian products in international markets.
Technological innovation, combined with careful management of quality parameters, consolidates the position of companies operating with standards of excellence, as evidenced by numerous international collaborations in the fruit and vegetable sector. Contact us now to improve your production line.