When preparing fruits and vegetables, it is recommended to peel as thin as possible to conserve nutrients. They are more concentrated toward the peels. The thicker outside covering removed, the more nutrients gone to waste.
Some vegetables are normally peeled but opting not also works. In such cases, cooking/eating them as is, is a good idea. Common examples are papaya, sayote, kalabasa and sponge gourd.
Green papaya and sayote for cooking tinola. I have never experimented and read about yellow papaya peels. Young green squash. I saw my colleague did this. Matured squashed with hard orange skin should be peeled. Sponge gourd wedge are usually removed because they are hard when bought from marketplace. Growers wait for this stage to get bigger harvest and more income. Wedge together with skin are perfectly edible when soft enough.
Others are simply discarded due to their bland or astringent taste. The rind of watermelon and santol. With little processing knowledge and some work, these could be transformed to delectable sweets. See “How to Make Sweet Nata de Pakwan (?) From Watermelon Peels” and “How To Make Santol Peels Candy“.
What if the separation between flesh and peel is very distinct. The peel in its entirety is coming off with ease. Thin removal is not viable. We cannot do anything about it even if we know its nutrient content is very high.
A perfect case for banana. Japan scientists found out very high levels of dopamine in banana Musa cavendishii, ranging from 80-560 per 100g peel. It is indeed very high compared to 2.5-10 mg in pulp.
If we weigh usefulness according to nutrient levels. Throwing away the flesh and eating the peel is better. The taste is not so nice but can be remedied by some cooking trick. Read the following posts for reference:
- How to Make Banana Peel and Onion Crackers
- How to Cook Banana Peel Chips and Dinuguang Saging
- How to Make Banana Peel Vinegar
According to the same study, dopamine is antioxidant even stronger than glutathione. It is popularly known as neurotransmitters. Important in overall body functions and prevents the onset of Parkinson’s disease.
Reference: High Content of Dopamine, a Strong Antioxidant, in Cavendish Banana
Kazuki Kanazawa and Hiroyuki Sakakibara
J. Agric. Food Chem., 2000, 48 (3), pp 844–848