Food Science: What are Fruits + Other Juicy Questions About Them (types, ripening, and why people think a tomato is a vegetable)

Wow, it has been quite a hot minute since I have published a post! Lately I have been crazily busy with school, finding a new job, and planning out my future post-graduation despite just being a third-year (still, I should have a solid route even though applications aren’t due until a year from now). Anyways, I thought I’d kick off the end of the year with another food science-related post because I genuinely love creating these informative breakdowns that pertain to my major. Research has never been more thrilling to me!

Since it is January and everyone wants to make healthier choices, fruit is a wonderful topic to tackle. It’s praised yet controversial for all the most intriguing reasons. Buy only organic fruit. Well, in reality, you don’t have to. Fruit is healthy for you. Except for the fact that it’s loaded with sugar which is horrible for you in every form. Zucchinis are the best vegetable ever. What if I told you it’s actually a fruit? UGH. The media can never be trusted.

Based on all my lectures from my university and the links I have found below, I’ve attempted to dissect almost everything and anything most individuals would like to know about fruit, including the botannical origins, types, how to detect ripeness, why some fruits turn brown, whether fruit is healthy or not, and many, many more. Please let me know below if you have any more suggestions for other posts!

So…what exactly are fruits?

  • Fruits can be defined as the fully developed ovarian structure of a plant that also encompasses the seeds and its surrounding components. Essentially, what blossoms from the flower’s reproductive parts becomes part of the fruit. Everything that does not pertain to floral reproduction is part of a vegetable. Therefore, the types of plants that do have seeds are technically considered fruits.

How many types of fruit are there?

  • Countless–it would take me an eternity to number them all. To gain an extremely broad overview of what type of fruits there are, here’s a list of the six families of fruits: the squash family, the berry family, the grape family, the citrus family, the rose fruit family (includes pomes and stone fruits), and the tropical fruits family.

Why do some fruits ripen after harvesting and some do not?

  • All fruits emit ethylene gas, a natural plant hormone that specializes in the regulation of plant maturity, such as when a flower blooms, a branch sheds its leaves, and when a fruit ripens. However, some fruits emit more ethylene gas than others, enabling them to continue maturing itself beyond harvesting. Any fruit that releases a significant amount of this natural gas after being picked off from its stem are known as climacteric fruits. Some examples include avocados, bananas, tomatoes, peaches, mangoes, and apples. Fruits that distribute little to no ethylene beyond harvesting are non-climacteric fruits, such as berries, grapes, melons, pineapple, pomegranates, and citrus fruits.

If a fruit is supposed to have seeds, why aren’t tomatoes, zucchinis, eggplants, and bell peppers classified as vegetables?

  • Botanically speaking, there are more “vegetables” that are actually fruits, such as eggplants, tomatoes, zucchini and bell peppers. However, there are legal and culinary parameters of a plant-based ingredient that determine whether this particular ingredient is a fruit, vegetable, nut, seed, and/or legume. What differentiates a fruit from a vegetable in terms of these legal and culinary standards distinguish taste and flavor yield as well as cooking use. Anything possessing savory and salty flavors are termed vegetables, whereas ingredients that are sweeter are defined as fruits by chefs. This is why most people believe the tomato is a fruit. In 1893, a Supreme Court ruling termed Nix v. Hedden justified that imported tomatoes should be taxed as vegetables, which are differently taxed from fruits based on culinary factors.
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Why do some fruits brown after I cut them (i.e. avocados)?

  • For browning to occur, fruits and vegetables must be exposed to oxygen. This is because the oxygen will react with polyphenol oxidase, a naturally occuring enzyme in the fruit, which oxidizes the amino acid tyrosine, producing quinones (brown, black, or red color molecules) that are further polymerized, thus exposing a browned effect. Not all fruits brown because not all fruits contain tyrosine, which is the specific amino acid that is reduced in the reaction. To combat this reaction, seal an opened fruit in a de-aired bag as soon as possible, squeeze lemon juice over the apples, and soak the apples in water with a little bit of salt, lemon juice, apple cider, or plain carbonated water. For avocados, store the open fruit next to an onion within the container.

How can I pick out the perfectly ripe fruit (i.e. watermelon, mango)?

  • There are several sensory cues that will determine the ripeness of the fruit:
    • Color: anything faded or around the green side of hue will be under-ripe, such as a dimly colored nectarine, fully green banana peel, a slightly green strawberry, or a mostly green mango. On the other hand, the more vibrant a fruit–specifically yellow, red, orange, or purple when it comes to grapes, cherries, blueberries, and apples (though some varieties of apples are naturally green).
    • Hardness and texture: people mostly utilize this cue when selecting watermelon, avocados, kiwis, or papayas. The softer the fruit, the riper it has developed. Most of the time, a somewhat “fleshy” texture is ideal because the ripeness quality falls somewhere in a happy medium. Anything too hard is unripe whereas an extremely squishy fruit is over-ripe, unless you want any of these types of ripening stages.
    • Smell: scent is absolutely critical–the stronger the sweetness or pungency of a smell, the riper the fruit is. Ideally, you want fruits that have a modest sweet smell given that the components of the flesh are not . This is a reason why overripe bananas have this extremely overbearing aroma–the sugars are completely fermented, thus bearing a bitter aroma that attract fruit flies (ew).
    • Hollowness: mainly when selecting melons and squash, the heaviness or lightness of a fruit can determine how ripe or unripe the fruit is. With the exception of melons, fruit should not be hollow inside. A hollow fruit suggests that the plant has been improperly pollinated, meaning that the plant may have not received enough pollen (thanks very highly in part to unsustainable agriculture practices), extreme climates, inconsistent moisture levels (too wet or too dry) , excessive fertilizer usage, and/or a lack of boron (a trace mineral that aids in solidifying cell walls and is found in the soil–can be alleviated by using just the right amount of fertilizer or an element mix with boron).
  • Note that you do not always want to pick out completely ripe fruit unless you will consume it right away. Slightly underripe fruits will mature incredibly quickly when brought home to a kitchen. Be sure to store these fruits accordingly to how you aim to optimize the ripening process.

Should I always buy organic fruit?

  • Oof, this is always a toughie to pick, given that there are valid arguments on both the pro-GMO side and the pro-organic side. As of lately, scientific consensus showcases limited evidence on the health advantages of organic fruit from non-organic fruit, but there are promising benefits for the environment and for smaller, local farms. In other words, it never hurts to purchase organic whenever you can, but you truly do not have to obsess over it. Having said that, see the dirty dozen, the fruits and vegetables that are ideal to purchase in organic form, versus the clean fifteen, which are the rest you can buy conventionally.

Lastly…is fruit healthy or not?

  • Well, let’s put it this way: fruits have antioxidants, vitamins, minerals, and fiber. They include a vast array of micro-nutrients that are beneficial for growth and development as well as the complexity to metabolize properly in our systems. Having said that, fruit still contains sugar. With a few exceptions, most fruits are relatively high in carbohydrates that some people demonize.

Hope this post makes your day a little juicier! Get it? Juice…sugar…fruit? Okay. I should stop now.


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