# The Impact of Freeze Drying on Bioactivity and Physical Properties of Food Products
## 4 Impact on Bioactive Properties
Although no lycopene was detected in fresh samples, interestingly, small quantities of lycopene were determined in all dried samples. In another study by [PERSON] et al., the bitterness, hygroscopicity, and antioxidant properties of soybeans were detected using FD and spray drying, and their results were compared with each other to obtain the best drying technique [123]. Even though FD reduced the degradation of the bioactive properties of the sample, spray drying was determined to be the most usable technique to preserve these properties. In a study, two different varieties of FD, vacuum and atmospheric FD, were used to explain the effect of the FD varieties on the broccoli quality after drying [124]. The bioactive properties of broccoli, including total selenium content, total polyphenol content, and anti-radical power, were determined for each FD variety. As an outcome, while atmospheric FD was chosen as the best technique for the retention of the antioxidant properties of broccoli, the best retention of the total phenolic content of the sample was obtained via vacuum FD. Also, other plant-based materials, including flowers and leaves, can be evaluated as food components for various industries and can be dried via FD to obtain high-quality products [125; 126]. The fresh and dried forms of these components can be used in various industries. With this perspective, different drying techniques are being developed and invented to utilize these components for years and obtain a dried sample which is rich in terms of nutritional value. For example, natural drying, microwave drying, hot air drying, infrared drying, vacuum drying, and FD were applied to _Bletilla striata_ (Thunb.) [PERSON] flowers [127]. FD was chosen as the most effective technique due to its high retention capacity for total phenols, total anthocyanins, and antioxidant properties, while also preserving the flower's characteristics and color with minimal browning. Other techniques yielded notable results as well: microwave drying had a low drying time; hot air drying exhibited a high browning capacity and long drying time but also had a high retention ability for total flavonoids and total polysaccharides, higher than FD; and natural drying resulted in almost complete degradation of anthocyanins. Also, the impacts of FD on basil leaves (_Oximum basilicum_) were investigated in another study conducted by [PERSON] et al. [73]. Higher concentrations of phenolic compounds, carotenoids, and flavonoids in the sample were obtained via FD fresh basil leaves. However, the vitamin C, chlorophyll a, chlorophyll b, and antioxidant activity of the leaves decreased slightly, resulting in a minimum degree of color and physical changes. Seafood draws the attention of consumers with its nutritional and functional properties [128; 129]. This food group is included in the food and supplement categories, and in both categories, production and storage conditions are evaluated to protect the content and extend long shelf life [130]. This category includes fish, shellfish, mollusks, marine plants, and other seafood. With the development of the natural and healthy nutrition trend in the last decade, the consumption of algae, one of the foods with proven health benefits, has also increased [131]. Algae offer valuable bioactive content in addition to protein, fat, carbohydrates, vitamin, and mineral content [131]. At this point, different techniques have been used to preserve its content [132]. The FD technique is used to increase the retention ability of the bioactive ingredients of the kinds of seafood after the drying processes [133]. Vacuum FD and vacuum spray drying were applied to myofibrillar proteins from silver carp in the article of [PERSON] et al. ; vacuum FD protected the protein of the sample more effectively than vacuum spray drying [134]. Also, this drying technique, which is highly protective of foods, was applied to the mushroom species. In a study, vacuum FD, oven drying, and air drying were used to dry _Cordyceps sinensis_[135].