ISLAMAABAD, 02 Oct (ABC): A recent study published in the journal ACS Food Science & Technology shows that substituting a small portion of wheat flour in cookies with banana peel flour enhanced the nutritional profile of the cookies without adversely impacting taste and texture. The incorporation of banana peel in the diet has the potential to reduce the emission of greenhouse gasses while providing health benefits.
“Banana peel consumption can benefit not only the grower (providing waste management solution), and the agricultural industry (generating income by converting waste material into value-added goods), but also contains a vast nutritional value that can deliver health benefits when consumed,” said Dr. Wolyna Pindi, a senior lecturer at Universiti Malaysia Sabah.
Banana peel as a food item
Bananas are the fourth most consumed food crop following rice, wheat, and maize. Banana peels account for nearly 35%Trusted Source of the weight of the fruit and generally end up in the trash bin or compost. However, banana peels contain high amounts of organic compounds, and their decomposition in landfills is a significant source of potent greenhouse gases such as methane.
Efforts to minimize waste have led to the utilization of banana peels for the production of biofuel, fertilizer, wastewater treatment, and other industrial applications. Banana peels are also edible and there has been a surge in interest in the use of banana peels as food to reduce waste.
In addition, the high levels of dietary fiber and antioxidants in banana peel make it a candidate for inclusion in a healthy diet. Specifically, banana peels contain high levels of phenolic compounds that have antioxidant properties and antimicrobial properties. These phenolic compounds may also have anti-inflammatory effects and potentially benefit individuals with diabetes and high blood pressure.
Banana peels are also rich in protein, potassium, magnesium, vitamins, polyunsaturated fatty acids, and amino acids.
Banana peel has been used as a meat alternative, including as a vegan substitute for pulled pork and bacon.
Banana peels also contain high levels of the amino acid tryptophan which can improve sleep quality. Furthermore, magnesium and potassium present in banana peels are associated with muscle relaxation. These properties and the high antioxidant levels have also led to the use of banana peel for brewing tea.
Banana peel flour has been used to enhance the nutritional properties of various food items, including bread and cakes. For instance, a previous study has shown that 5% to 10% of wheat in bread can be substituted with banana peel flour to increase the nutritional profile without negatively influencing taste or other sensory properties such as color, aroma, and texture.
Researchers at Aligarh University recently examined whether supplementing wheat flour with banana peel flour could also enhance the nutritional properties of cookies.
Impact on the nutritional profile
The researchers first removed the peels from washed, undamaged ripe bananas to prepare the banana peel flour. After blanching and drying the banana peels, the researchers ground the banana peels into flour and substituted a small amount of refined wheat flour in the cookie recipe with the banana peel flour.
The researchers prepared five batches of cookies, substituting 0% (control), 7.5%, 10%, 12.5%, or 15% of the wheat flour with banana peel flour. Increasing the amount of banana peel flour in the cookies resulted in higher moisture and mineral content, but lower fat and protein content. The increase in moisture content was likely due to the higher fiber content in banana peel flour.
Moreover, the cookies with higher banana peel flour concentrations also showed higher phenolic compounds and antioxidant potential levels. In other words, except for the decline in protein levels, increasing the banana peel flour levels in the cookies improved the nutritional profile.
Antioxidant and sensory properties
Cookies contain high levels of fat and oxidation of these fats can reduce the shelf life. Given the high levels of antioxidants in banana peels, the researchers also examinedbanana peel flour’s ability to improve cookies’ shelf-lifes over a 3-month storage period.
The researchers found that the levels of phenolic compounds and the antioxidant properties of all cookies declined over the 3-month storage period. But the cookies containing 15% banana peel flour still showed higher levels of polyphenols and antioxidant potential at the end of three months than the control group. Significantly, the cookies with higher banana peel flour content also showed greater inhibition of fat oxidation.
The researchers recruited a trained panel of 20 judges to assess the taste and other sensory characteristics associated with the desirability of food, such as taste, texture, and appearance.
The flavor and aftertaste of cookies with 7.5% or 10% of the wheat flour substituted with banana peel flour were comparable to that of control cookies. Moreover, the scores for texture and overall acceptability of cookies with the lowest amount of banana peel flour (7.5%) were better than the control group and other cookies with higher banana peel concentrations.
These results show that substitution of wheat flour with banana peel flour at low concentrations could enhance the nutritional profile of cookies, without negatively impacting sensory attributes.
Need for further research
Although the consumption of banana peels may confer health benefits, there is limited data on the safety and impact of processing methods on the nutritional properties of banana peels.
The study’s co-author Faizan Ahmad, professor at Aligarh Muslim University, cautioned, “Banana peels are not safe to consume in their raw form due to their exposure to various environmental pollutants, pesticides, bacteria which can negatively affect the health, therefore they need an extra preparation before the consumption.”
Furthermore, some studies have shown that drying banana peels at high temperatures can lead to the loss of beneficial compounds. Cooking food products containing banana peel flour could lead to further loss of these compounds.
Fruit peels are also prone to the accumulation of toxic substances such as heavy metals and pesticides. Thus more research and regulations are needed before the widespread use of banana peel as a food item.
“There is a lack of validated standards to allow banana peel commercialization in the food industry. Also, the inadequately organized system and guidelines, as well as a lack of subsidies are anticipated to be obstacles to banana peel / other agricultural biomass utilization,” said Dr. Pindi.
Banana peel also contains antinutrients,Trusted Source such as tannin, oxalate, and phytate, which can limit the absorption of food and adversely impact health. Dr. Pindi said, “Extra modification and processing may be required to reduce the presence of antinutrients (oxalate, phytate, etc.) in the banana peels.”
