Postharvest commercial processing technology of strawberry

Strawberries are not only visually appealing with their vibrant red color, but also offer a unique balance of sweetness and tartness. Rich in essential nutrients such as vitamin C, antioxidants, and fiber, they are considered one of the most valuable fruits in terms of flavor, aroma, and nutritional value. Often referred to as the "Queen of Fruits," strawberries have gained popularity both domestically and internationally. However, due to their delicate nature, they are highly susceptible to damage and microbial contamination during harvesting and transportation, which can lead to spoilage, reduced commercial value, and significant economic losses. In recent years, strawberry production has increased rapidly, but challenges in post-harvest handling have limited their marketability and shelf life. The concentration of harvest periods often results in large quantities of fruit being available at once, leading to overstocking, poor storage conditions, and high rates of rot. This not only causes waste but also harms the environment and discourages farmers from expanding their operations. Therefore, it is crucial to develop effective post-harvest processing and preservation techniques to extend the shelf life of strawberries and ensure their quality during transport and storage. **Preparation Before Storage** 1. **Variety Selection**: Choosing the right variety plays a key role in storage performance. Varieties like Jixin, Shitou, Gorera, Baozao Zaosheng, Green Seeds, Brandon Baoshuo, and others are known for their better resistance to decay and suitability for long-distance transport. 2. **Harvesting**: Strawberries should be harvested when approximately three-quarters of the fruit surface turns red. It's best to pick them on sunny days, after the morning dew has dried or before the temperature drops in the early evening. Avoid picking during midday when temperatures are high. Hand-picking is recommended, and care must be taken to avoid damaging the fruit. Remove any diseased or damaged berries and gently place the healthy ones in special fruit trays or baskets. The ideal size for fruit trays is 90 cm x 60 cm x 15 cm. After filling, the fruit should be placed in polyethylene bags and quickly sent to cold storage. 3. **Sorting**: After harvesting, remove any rotten, diseased, or deformed fruits. Select only those that are uniformly colored, well-shaped, and free from blemishes. 4. **Cleaning**: Use a strawberry washing machine to clean the fruit. After washing, soak the strawberries in a 0.05% potassium permanganate solution for 30–60 seconds, then rinse thoroughly with water and allow to drain. 5. **Pre-cooling**: Pre-cooling is essential to maintain quality. As soon as possible after harvest, move the fruit into cold storage. Special containers should be arranged with at least 15 cm between rows to prevent freezing. Maintain humidity above 90% and a temperature around 5°C (not below 3°C). In April and May, when temperatures rise, keep the storage room at 7–8°C. Avoid frequent opening and closing of the storage area for at least two hours after placement. If the fruit temperature is around 15°C, it should be pre-cooled for at least two hours. For fruit at 20°C, pre-cooling for 2–4 hours is recommended. **Storage and Preservation Techniques** 1. **Refrigeration**: The ideal storage temperature for strawberries is 0°C with 90–95% relative humidity. After harvest, the fruit should be quickly cooled to 1°C in a refrigerated environment. 2. **Wax Coating**: A promising technique involves using chitosan-based coatings, which help maintain firmness and nutrient content. An optimal concentration of 0.5% chitosan is recommended, or a composite coating of 0.8% ethylparaben and 0.5% stearate monoglyceride can also be used for enhanced preservation. 3. **Calcium Treatment**: Soaking strawberries in calcium solutions helps reduce weight loss, preserve texture, and inhibit microbial growth, thereby extending their shelf life. 4. **Modified Atmosphere Storage**: Store strawberries at 0–0.5°C with 85–95% humidity and an oxygen level of 3% and carbon dioxide of 6%. Sorting by size and maintaining proper spacing between boxes is important for air circulation. 5. **Chemical Treatments**: - **Phytic Acid Treatment**: Soaking strawberries in a solution containing 0.1–0.15% phytic acid, 0.05–0.1% sorbic acid, and 0.1% peracetic acid allows for storage at room temperature for up to one week and at low temperatures for 15 days, with a good fruit rate of 90–95%. - **Sulfur Dioxide Treatment**: Using sulfur dioxide slow-release agents in plastic containers improves storage efficiency. With one bag per container, strawberries can be stored for 20 days with a good fruit rate of 66.7%. **Transportation** For transporting strawberries, refrigerated trucks are the best option. It’s advisable to load and unload during cooler hours, such as early morning or late evening. Use small, sealed packaging with 10% carbon dioxide inside the plastic bags. Handle the fruit gently to avoid bruising, and ensure that the transport vehicles are clean and equipped with sun protection, insulation, and rain coverage. Proper handling during transit ensures that strawberries arrive at their destination in excellent condition.

Rating Ruler

Rating ruler, also known as a grating ruler displacement sensor (grating ruler sensor), is a measurement feedback device using the optical principle of grating.Grating ruler is often used in the closed-loop servo system of CNC machine tools, which can be used to detect linear displacement or angular displacement. The output signal is digital pulse, which has the characteristics of wide detection range, high detection accuracy, and fast response speed. For example, in the CNC machine tool is often used to detect the coordinates of the tool and the workpiece, to observe and track the tool error, and to play a role in compensating the tool motion error.

Rating Ruler

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