Freshly cut fruit packaging
Reading Time: 9 minutes
2025/01/20
The Effect of Modified Atmosphere Packaging on Respiration and Enzymatic Activities of Sliced Fruits
Fruit production lines can include a variety of steps, such as receiving, washing, sorting, grinding, and packaging. The steps may vary depending on the type of fruit being processed:- Sorting and cutting
- Crushing
- Packaging
PACKAGING PROGRESS
In terms of packaging innovation, “the goal is to get to the longest shelf life possible, both for the retailer and the end consumer. We are always looking at ways to extend the shelf life while keeping it all natural and avoiding preservatives. The point is that there are challenges in the procedure of packaging:Respiration
Respiration is the process by which plants take in oxygen and give out carbon dioxide. Respiration is a basic reaction of all plant material, both in the field and after harvest. Fresh products continue to lose water after harvesting; however, unlike growing plants, they can no longer replace the lost water from the soil, and therefore must rely on the remaining moisture content at the time of harvest. This water loss from fresh products post-harvest is a serious issue that leads to weight reduction. Effect of Air Supply on Respiration. Respiration depends on a good air supply. Air contains about 20 percent of the oxygen essential to normal plant respiration, during which starch and sugars are converted to carbon dioxide and water vapour. When the air supply is restricted and the amount of available oxygen in the environment falls to about 2 percent or less, fermentation instead of respiration occurs. Fermentation breaks down sugars to alcohol and carbon dioxide, and the alcohol produced causes unpleasant flavours in products and promotes premature ageing. The Effect of Carbon Dioxide on Respiration. Poor ventilation of products because of restricted air supply leads also to the accumulation of carbon dioxide around the products. When the concentration of this gas rises to between I and 5 percent in the atmosphere, it will quickly ruin products by causing bad flavours, internal breakdown, failure of fruit to ripen and other abnormal physiological conditions. Thus, the proper ventilation of products is essential.
Transpiration, or the Loss of Water
Most fresh products contain between 65 to 95 percent water. Transpiration in sliced fruits is a phenomenon that occurs when fruits are cut, referring to the release of water from the cut surface of the fruit. This process happens for various reasons and has specific effects on the quality and shelf life of sliced fruits.Texture Changes
The texture attributes of plant tissues vary during postharvest handling, as they depend on many factors, such as the stage of maturity, water stress, storage temperature and relative humidity, rough handling, and the ripening process. Changes observed in several products include softening, turgor loss, and increased elasticity or toughness, leading to a significant product quality deterioration. These negative phenomena may be caused due to the transpiration process or the activity of several enzymes or mechanical injuries that occur during transport and storage. Enzymes, such as β-galactosidase, polygalacturonase, pectin methyl esterase, cellulose, phenylalanine ammonia-lyase, peroxidase, and cellulase, may lead to cell-wall modification and significant pectin degradation. Examples of such textural defects involve pectin degradation in strawberries, hardness increase in carrot, mushiness in cantaloupe, etc.Color Changes
Color is considered one of the most decisive factors for a consumer’s acceptance or rejection of commodities, such as fresh-cut fruits and vegetables, and is frequently used as an indicator of the overall quality level and maturity stage of the final product. Color is significantly affected by factors, such as the particular cultivar, temperature and relative humidity conditions, and postharvest handling procedures. Color changes are induced by anabolic or catabolic reactions of pigment compounds, including chlorophylls (green), anthocyanins (red, blue, and purple), and carotenoids and flavonoids (yellow and orange). These changes may occur as a consequence of the ripening process, but they also can be induced by mechanical injuries on cell tissues during handling and fresh-cut processing. Another frequent cause of color degradation in fresh-cut fruits is associated with enzymatic activity (for example, of PPO (polyphenol oxidase) and POD (peroxidase)) that follows cell-wall damage, which enables the immediate contact of enzymes, substrates, and oxygen. The browning of apples, peaches, pears, avocados, etc., is considered a major defect of these commodities and depends on the presence of phenolic compounds (the necessary substrate), the activity of polyphenol oxidase (PPO), and the concentration of antioxidants within the fruit cells. The composition of plant tissue is constantly changing, not only during growth and ripening but also after harvest, leading to either positive or negative quality characteristics. Among these compositional changes, the content of soluble solids and acidity (and especially their ratio) is often used as a quality metric for selecting products for processing and determining harvest time. Such changes are more pronounced in climacteric products (climacteric fruits or ethylene-dependent fruits are those that continue to ripen after being harvested from the tree or plant) as they continue to ripen even after harvest. The flavor characteristics of most fruits are influenced by the concentration of sugars (sweetness), organic acids (acidity), phenolic compounds (bitterness), and specific volatile compounds (aroma). Loss of volatile compounds can be associated with the ripening process, improper storage conditions, or the enzymatic activity of relevant enzymes such as peroxidases and lipoxygenases. Regarding nutritional factors, fresh fruits and vegetables are recognized as good sources of vitamins, minerals, dietary fiber, and several types of compounds with antioxidant properties (flavonoids, carotenoids, polyphenols, and other phytonutrients). Significant loss of these substances during handling and processing after harvest is measured. These losses are mainly due to physical damage to the cell wall, inappropriate temperature and relative humidity conditions during storage, and freeze damage to sensitive products."
Ripening of Fruits
Fleshy fruits undergo a natural stage of development known as ripening. This occurs when the fruit has ceased growing and is said to be mature. Ripeness is followed by ageing (often called senescence) and breakdown of the fruit. There are two characteristic types of fruit ripening that show different patterns of respiration:- Non-climacteric fruit ripening
- Climacteric fruit ripening
