Freezing blueberries enhances their antioxidant effects... 4 foods that are good to freeze
Freezing tofu increases its protein concentration, allowing for sufficient protein intake with fewer calories. When freezing moisture-rich foods like tofu, water escapes, but nutrients such as proteins, which have larger particles, cannot escape and become concentrated. The protein content of raw tofu is 7.8g per 100g, but frozen tofu has been found to contain 50.2g of protein per 100g, approximately six times that of raw tofu. Additionally, a study published in the Journal of Food Biotechnology reported that frozen tofu exhibited higher hardness, adhesiveness, and chewiness compared to the control group. When cooking frozen tofu, it can be thawed at room temperature or microwaved for about 3 to 4 minutes.
Like tofu, broccoli loses moisture and concentrates nutrients when frozen. Therefore, it allows for more effective intake of nutrients such as dietary fiber, vitamins, and minerals. In particular, broccoli contains twice as much vitamin C as lemons, seven times as much as potatoes, and 6 to 7 times as much as tangerines. To minimize the loss of vitamin C, it is best to add a little salt to boiling water and start boiling the broccoli from the stem when cooking. After blanching briefly, cut it into bite-sized pieces and freeze.
Frozen blueberries not only taste good but also increase the concentration of anthocyanins. Anthocyanins are compounds that prevent the accumulation of active oxygen, providing antioxidant effects. In fact, a study from South Dakota State University in the United States found that fresh blueberries contain an average of 3.32 mg/g of anthocyanins, while frozen blueberries contain an average of 8.89 mg/g. Additionally, when blueberries are kept at room temperature, vitamins are easily lost due to sunlight and other factors, but freezing helps preserve the vitamins. According to a paper published in the Journal of Agricultural and Food Chemistry in the United States, consuming blueberries frozen allows for more effective intake of vitamins B and C compared to eating them raw.
Spinach also loses some vitamins and folate over time, but freezing can help preserve these nutrients for a longer period. There is a study from Pennsylvania State University in the United States indicating that frozen spinach contains more folate and carotenoids than spinach stored at room temperature. Folate helps improve brain function and cardiovascular health, while carotenoids act as antioxidants and protect the eyes.