Is bitter broccoli safe to eat? (Health benefits)
In this brief guide, we will answer the question “Is bitter broccoli safe to eat?”. We also will discuss how broccoli becomes bitter and its health effects.
Is bitter broccoli safe to eat?
Yes, bitter broccoli is safe to eat. The distinctive pungent aroma and bitter taste of broccoli are attributed to compounds known as glucosinolates. Glucosinolates are a group of sulfur-containing compounds found in cruciferous vegetables like broccoli and cauliflower.
These compounds serve as natural defenses in plants, acting as secondary metabolites. When the plant’s tissue is damaged, either through chopping or chewing, an enzyme called myrosinase interacts with glucosinolates, causing their breakdown and the creation of various bioactive compounds that may offer potential health benefits. (1)
What is the nutritional value of broccoli?
Broccoli is renowned for its rich nutritional content, boasting high levels of vitamins, antioxidants, and compounds with potential anticarcinogenic properties. This cruciferous vegetable is considered a nutritional powerhouse, containing essential bioactive compounds such as polyphenols, flavonoids, carotenoids, sulforaphane, and glucosinolates.
In terms of vitamins, broccoli provides a wide array, including vitamins A, B6, B12, C, D, E, K, thiamine, riboflavin, niacin, folate, as well as trace amounts of pantothenic acid, choline, and betaine.
Additionally, it is a source of essential minerals like calcium, potassium, sodium, and phosphorus. It also contains small quantities of zinc, selenium, iron, magnesium, and manganese. Due to its exceptional nutritional profile, broccoli is commonly recommended for daily consumption by food authorities worldwide. (2)
What are the health benefits of glucosinolates?
Glucosinolates, such as glucoiberin, glucoraphanin, glucoalyssin, glucoerucin, glucoibervirin, gluconapin, and 4-methoxyglucobrassicin, are bioactive compounds found within the vacuoles of cruciferous vegetable cells. Broccoli is one cruciferous vegetable that contains various types of glucosinolates. The composition of these compounds can vary among different cultivar types.
These compounds undergo metabolic transformation into the biologically active isothiocyanate (ITC) known as sulforaphane, which is renowned for its role in reducing the risk of certain cancers such as lung, esophageal, and gastrointestinal cancer. (2)
What factors affect the level of glucosinolates in broccoli?
The levels of glucosinolates (GLS) in harvested broccoli crops are primarily influenced by genetic factors, as well as by environmental conditions during the growing season, and subsequent post-harvest factors, which encompass storage conditions and processing.
When broccoli tissue is damaged through biting, chopping, or other means, the enzyme myrosinase is released from ruptured cells. Myrosinase plays a key role in catalyzing the breakdown of various glucosinolates, resulting in the formation of multiple metabolites, including glucose, sulfate, nitrite, isothiocyanate, and thiocyanate.
The storage temperature significantly impacts the glucosinolate content in broccoli. Stable levels of total glucosinolates are maintained when stored at 4 °C, whereas a decline is observed during storage at 20 °C.
However, there have been reports of either no change in total glucosinolate levels or a reduction in total glucosinolates in broccoli during storage at temperatures ranging from 1 to 22 °C.
Notably, an increase of 42% in total glucosinolates was reported in broccoli florets after storage at 10 °C. Consequently, the exact effects of storage temperature on glucosinolate content in broccoli are still not fully understood. (3, 4)
Is it possible to remove broccoli bitterness?
Yes, since cooking can cause substantial loss of glucosinolates toning down the bitterness as there is a strong correlation between bitter taste and several major glucosinolates in broccoli. Various methods of cooking are followed in households daily, such as steaming, boiling, microwaving, stir-frying, and stir-frying followed by boiling.
All the cooking methods except steaming result in a notable decrease in different types of glucosinolates, chlorophyll, vitamin C, soluble protein, and soluble sugars. Steaming of broccoli was reported to produce increased levels of polyphenols and glucosinolates. (2, 5)
Is there any risk in broccoli consumption?
Yes, there are some considerations when it comes to broccoli consumption. One of the most common side effects of broccoli is bowel irritation, largely due to its high fiber content. Individuals who are regularly taking blood thinners, such as warfarin, are advised to avoid broccoli because of its high vitamin K content, which can potentially interfere with the blood-thinning effects.
Additionally, people with hypothyroidism are recommended to steer clear of broccoli and other brassica vegetables, as they may disrupt thyroid hormone production. It’s worth noting that there have been reports of genotoxic activity associated with broccoli, attributed to the degradation product of glucosinolates. (2)
In this brief guide, we answered the question “Is bitter broccoli safe to eat?”. We also discussed how broccoli becomes bitter and its health effects. From my perspective as a food scientist, bitter broccoli is safe to eat, and it’s possible to mitigate the bitterness by various cooking methods.
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SYED, Rahamat Unissa et al. Broccoli: A multi-faceted vegetable for health: An in-depth review of its nutritional attributes, antimicrobial abilities, and anti-inflammatory properties. Antibiotics, v. 12, n. 7, p. 1157, 2023.
JAISWAL, Amit K. (Ed.). Nutritional composition and antioxidant properties of fruits and vegetables. Academic Press, 2020.
RYBARCZYK-PLONSKA, Anna et al. Glucosinolates in broccoli (Brassica oleracea L. var. italica) as affected by postharvest temperature and radiation treatments. Postharvest Biology and Technology, v. 116, p. 16-25, 2016.
LI, Zhansheng et al. Variation of sulforaphane levels in broccoli (Brassica oleracea Var. Italica) during flower development and the role of gene Aop2. Journal of Liquid Chromatography & Related Technologies, v. 37, n. 9, p. 1199-1211, 2014.
WHITAKER, B. D. Postharvest flavor deployment and degradation in fruits and vegetables. In: Fruit and Vegetable Flavour. Woodhead Publishing, 2008. p. 103-131.