Characteristics and functional properties of green banana flour: An opportunity for functional bread production

The demand for functional food products has led to an increased interest in nutrients such as minerals, vitamins, bioactive compounds, fibre and prebiotics to be present in food formulations. Amongst the prebiotics, Resistant starch (RS) has gained more attention in recent years, due to its acknowledged health benefits such as prevention and control of colon cancer, diabetes, and obesity. Banana, the world’s most favourite fruit, is one of the richest sources of RS at early stages of ripeness, when it is green (unripe). According to some estimates, more than 100 billion bananas are consumed globally each year, with an annual per capita consumption of 20 kg. Green banana pulp is a rich source of essential phytonutrients, phenolic compounds, vitamin B group, ascorbic acid and tocopherols, while the green banana peel is a rich source of minerals, bioactive compounds and dietary fibre (DF) such as pectin, cellulose, hemicelluloses and lignin. Considering the nutritional value of both pulp and peel of green bananas, the production of green banana flour (GBF), which can be obtained by proper drying techniques, provides a way to preserve the nutritional benefits and increase the shelf-life of banana nutrients. White bread is the most popular bread type in the world, however, there is a growing research on fortifying bread with an array of different DF and functional compounds to take advantage of bread as a carrier of health benefiting compounds. Very few studies available that considered the effect of the GBF on technological properties, nutritional aspects and volatile fingerprint. The physicochemical and thermal properties of GBF obtained from air oven drying (ODF) at three temperatures (50, 80 and 110 °C) and freeze-drying (FDF) were compared to white wheat flour (WF). Lightness and yellowness were negatively affected by the oven temperature increment. The FDF samples exhibited higher a* and L* values and had the closest browning index to WF (P-value 0.05). While the ODF110 presented the highest pasting temperature (81.23 °C) and breakdown viscosity (7118.67 cp) amongst the GBF samples, ODF50 were the only heat-treated samples that showed similar hold, final and setback viscosity values to those found in the FDF. In terms of mineral contents, all GBF samples had higher concentrations of K, Mg, Ca and Zn compared to the WF which makes GBF as a better source of these nutrients (P-value 20% fortification level was observed. The ODF-fortified samples had higher browning index compared to control and FDF ones. The addition of both GBF types improved macro minerals (Mg, Ca, Na, K and P) without a significant change in micro minerals (Fe, Zn, and Mn). The use of FDF in bread resulted in a marked increase in both resistant and slow digestible starch content in F30 compared to ODF fortified samples at their comparable fortification levels. GC-MS-based chemical fingerprinting successfully detected more than 100 volatile compounds in the GBF fortified bread samples. Chemometrics methods used to compare the effect of GBF type in bread (FDF and ODF-fortified-bread), fortification level (10%, 20% and 30%) and bread part (crumb and crust) on the formation of volatile compounds. Furan (furfural, 2-furanmethanol), Strecker aldehydes (2- methyl butanal and 3-methylbutanal) and ketone (2-undecanone) were the most abundant volatiles in crust while alcohol (1-hexanol and 1-heptanol) and ester (ester butanoic acid ethyl) abundant in the breadcrumb. The level of fortification had a significant impact on the formation of 3-methyl-butanal (P-value < 0.05). Furthermore, bread made with freeze-dried GBF had more distinguished ‘banana-like’ flavour due to the presence of ethyl ester butanoic acid and 2-undecanone, while bread made with ODF represented more Maillard-related compounds which could signify a wood malty aroma impression. It can be concluded that fortification of bread with the GBF achieved from freeze drying had a more desirable results from technological and nutritional points of view. Although between 10% and 20% fortification level there was no clear difference, the 30% bread samples showed a high value nutritious bread with distinctive volatile flavour. Overall, the type of the drying method of GBF preparation had an impact on developing discriminant volatiles compared to bread part and fortification level

The Effect of Bread Fortification with Whole Green Banana Flour on Its Physicochemical, Nutritional and In Vitro Digestibility

The use of Whole Green Banana Flour (WGBF) in bread production may be a strategy to improve the nutritional profile of bread, but the extent of improvement may depend on the processing conditions of the flour. Therefore, WGBF was produced using two methods (freeze-drying and air-oven drying) and was used in bread-making. This study investigated the effect of flour type&mdash;FDF (WGBF produced by freeze-drying) and ODF (prepared by air-oven drying at 50 &deg;C)&mdash;at fortification levels of 0% (control), 10%, 20%, and 30% on the fortified bread. A significant decrease in energy caloric value and an increase in moisture and fibre at &gt;20% fortification level (p &lt; 0.05) was noted. The ODF bread samples had a higher browning index compared to the control and the FDF samples. Addition of WGBF improved macro minerals (Mg, Ca, Na, K, and P) with a no significant change in micro minerals (Fe, Zn, and Mn). The use of FDF in bread resulted in a marked increase in resistant and slow digestible starch levels in F30 compared to ODF samples and their comparable fortification levels. The digestibility of the bread samples showed that WGBF can be used as an alternative functional ingredient to prepare bread with better nutritional value

Tropical foods as functional foods for metabolic syndrome

du Preez, R ORCiD: 0000-0003-2164-0819Tropical foods are an integral part of the traditional diet and form part of traditional medicine in many countries. This review examines the potential of tropical foods to treat signs of metabolic syndrome, defined as a chronic low-grade inflammation leading to obesity, hypertension, impaired glucose tolerance, insulin resistance, dyslipidaemia and fatty liver. It is a major risk factor for cardiovascular and metabolic disease as well as osteoarthritis and some cancers. Tropical foods such as seaweeds and tropical fruits including indigenous fruits such as Davidson's plums are effective in reducing these signs of metabolic syndrome in rats, as well as reducing degeneration of bone cartilage and altering gut microbiome. Further, waste products from tropical fruits including mangosteen rind, coffee pulp and spent coffee grounds provide further options to reduce metabolic syndrome. Production of local tropical foods and local recovery of food waste from these foods could allow the development of commercial, sustainable and cost-effective functional foods in tropical countries. The aim is to develop these functional foods to reduce the incidence of metabolic syndrome and decrease the risk of costly chronic cardiovascular and metabolic disorders locally and globally