When you take a bite of a crisp apple, does the tangy and sweet, refreshing flavor invigorate you? This unique taste experience is largely attributed to the natural organic acids contained within the apple. For the average consumer, it's a delightful sensory pleasure; for professionals in the field of plant extracts and the food industry, it conceals a star molecule worth billions. So, what acids are actually present in apples?
I. The Soul of Apple Flavor: The Organic Acid Family Dominated by Malic Acid
First, let's address the core question: the primary acidic substance in apples is malic acid. Scientific research indicates that malic acid is the most significant organic acid in apple fruits, accounting for an absolute majority of total organic acids, typically reaching around 90%. It is this acid that defines the distinctive mild yet persistent sourness characteristic of apples.
Of course, the organic acids in apples are not limited to malic acid alone. They also include other types of organic acids, though in relatively lower concentrations. According to a 2012 study, analysis of apple juice samples revealed not only substantial malic acid but also trace amounts of citric acid and minute levels of tartaric acid.[2]
The composition and proportions of various organic acids in apples may vary depending on the variety, ripeness, origin, and storage conditions.[1] For instance, some research indicates that as the fruit ripens, the malic acid content undergoes significant changes-a process closely linked to the fruit's respiration and sugar-acid transformation.[3]
II. The Commercial Journey of Malic Acid: From Natural Extraction to Widespread Application
The value of malic acid far exceeds its role in imparting flavor. As a dicarboxylic acid, it possesses unique chemical properties and physiological functions, making it highly favored in fields such as plant extracts, food and beverages, and pharmaceuticals.
1. Functionally superior food additives:
- Acidity regulator: Malic acid has a stronger sourness than citric acid (approximately 1.2 times that of citric acid), but it offers a smoother and more natural fruity taste, avoiding the sharp, irritating sensation often associated with citric acid. Consequently, it is frequently used in premium beverages, jams, candies, and similar products to adjust pH levels and deliver a more natural flavor profile.
- Flavor Enhancer and Masking Agent: Citric acid can enhance the fruity aroma in products while effectively masking bitterness or off-flavors caused by certain ingredients (such as high-intensity sweeteners or specific nutrients).
- Color retention and preservation: By chelating metal ions, malic acid prevents pigment degradation caused by oxidation, acting as a color protector. Additionally, adjusting acidity can inhibit microbial growth, extending the product's shelf life.
2. Potential stocks in the health and wellness sector:
- Participant in Energy Metabolism: Malate is a key intermediate in the human tricarboxylic acid cycle (TCA Cycle) and directly participates in the energy production process. Therefore, it is believed to help combat fatigue and enhance energy levels.
- Promoting mineral absorption: Malic acid can form soluble chelates with minerals such as calcium and iron, enhancing their solubility and bioavailability in the intestines.
- Skin Care: In the fields of cosmetics and personal care, malic acid, as a gentle alpha-hydroxy acid (AHA), is used to promote the metabolism of the stratum corneum, thereby improving skin smoothness and brightness.
Due to its diverse functions, malic acid has become a significant product in the plant extract and fine chemical industries. It can be naturally extracted from fruits such as apples and is also produced on a large scale through chemical synthesis or microbial fermentation methods to meet the substantial market demand.
For more details about apple extract, connect with Serrisha from APPCHEM. (Email: cwj@appchem.cn; +86-138-0919-0407)
Reference
[1]POTENCIAL BIOATIVO E TECNOLÓGICO DE POLPAS DE PITAYA (Hylocereus spp.) FRESCAS E DESIDRATADAS. Mariana Angonese. [2020-10-09]
[2]GÜNEYDOĞU ANADOLU BÖLGESİ'NDE YETİŞTİRİLEN ZİVZİK ve GÖRÜMLÜ NARLARININ FİZİKOKİMYASAL ÖZELLİKLERİNİN BELİRLENMESİ. Gülşah İZOL. [2012]
[3]Zhao Yonghong, Li Xianli, Jiang Zesheng, et al. Study on Organic Acid Metabolism during Fruit Development of Protected Oil Peach[J]. Chinese Journal of Eco-Agriculture, 2007. [2007-09-15]