Fatty acid composition of different fruits and berries - A comparative study of superfruits and more “common” fruits

Abstract

Introduction: Superfruits have been promoted as nutrient-rich food that can improve your health, however, many scientists argue that the validation of the term is based on exaggeration of the limited studies that are available.

Background: The chemical composition of a food is complex and there are many substances that can affect the human body. One such group of substances are fatty acids (FAs), which have been observed to contribute to both positive and negative health effects. This field is in need of more research on the FA composition of different fruits and of more comparative research between superfruits and more “common fruits”.

Aim: The aim of this study is to quantitatively and qualitatively investigate the FA composition of three common fruits (bananas, apples, and strawberries) and three superberries (goji berries, white mulberries, and cranberries), and to compare their FA composition in order to detect any existing differences.

Methods: The samples were prepared by freeze-drying, lipid extraction, and derivatization into fatty acid methyl esters (FAMEs). The FAMEs were then analysed with gas chromatography coupled to a flame ionization detector (GC-FID). Two different GC-columns were used in order to be able to detect all possible FAs. External calibration was used for the quantitative determination and the polyunsaturated fatty acid per saturated fatty acid (PUFA/SFA) and omega-6/omega-3 (ω-6/ω-3) ratios were used to compare samples.

Results: The average total FA concentration ranged between 1.6 and 19.3 mg/g dry sample in the analysed samples. In general, most samples contained favourable FA compositions, with PUFAs as the major group, and preferable PUFA/SFA and ω-6/ω-3 ratios.

Conclusions: In conclusion, there was no statistically significant difference (P > 0.05) of the FA composition between more common fruits and superfruits. However, individual berries in both groups have been shown to contain fatty acid compositions that are of more nutritional value than others.

Popular Abstract

A group of fruits and berries that have gained a lot of popularity in recent years are superfruits and superberries. They are described as “nutrient-rich food considered to be especially beneficial for health and well-being” in the Oxford English Dictionary. However, there is no legal definition. Research has suggested that superfruits and superberries can be good sources of some important nutrients, which is one argument that marketers use when selling exotic superfruits and berries, usually at a higher price. However, some scientists argue that the term superfruit actually is a marketing term and that marketers are exaggerating the limited research that is available. The aim of this project is therefore to determine the fatty acid composition and concentration in three common fruits and berries (apple, banana, and strawberry) and three superberries (goji berry, cranberry, and white mulberry). Another aim is to compare their fatty acid composition and to see if there is any difference that can support the claims marketers make. Common fatty acid classes are saturated, monounsaturated, and polyunsaturated fatty acids. The human body can synthesise fatty acids, except some essential fatty acids like linoleic acid and α-linolenic acid, which are omega-6 and omega-3 fatty acids, respectively. They need to be obtained from the diet, which is why they are called essential fatty acids. The ratio between omega-6 and omega-3 fatty acids has been associated with future risk of different diseases and can be used as a measure of which food has a better fatty acid composition. A ratio around 1:1 has been suggested to be the most beneficial for humans. The ratio between polyunsaturated and saturated fatty acids can also be used as a measure of the nutritional value of the fatty acid composition, where a high ratio is better. The fatty acid composition was determined with a gas chromatograph coupled to a detector. The gas chromatograph separates compounds based on boiling point and how polar they are. The samples were, however, first prepared by extracting the lipids and then converting them to a more volatile form. After identification of fatty acids and calculation of concentrations, it could be observed that most of the fruits and berries had a high ratio between polyunsaturated fatty acids and saturated fatty acids and that the omega-6/omega-3 ratio was between 1:1 to 5:1 in most cases. However, no differences in the fatty acid composition could be observed between the groups superberries and common fruits, although some individual fruits and berries in both groups showed better ratios than others. Overall, strawberry was observed to have a more favourable fatty acid composition when considering both ratios. The results led to the conclusion that there is no difference of the fatty acid composition between superberries and more common fruits and berries.

• author: Bajramova, Azemina
• supervisor: Peter Spégel
• organization: Department of Chemistry
• course: KEML10 20211
• year: 2021
• type: M2 - Bachelor Degree
• subject: Chemistry
• keywords: Analytical chemistry, Comparative study, Fatty acids, Health impact, Quantification, Superfruits
• language: English
• id: 9055297
• date added to LUP: 2021-06-16 12:01:56
• date last changed: 2021-06-16 12:01:56