Production of fermented sweet potato flour using indigenous starter cultures

Abstract

The present study develop various microorganisms for starter culture purpose from fermented sweet potato and used the developed starters in the fermentation of sweet potato and products for consistent quality product with improved hygiene. Sweet potato was purchased from different markets and microorganisms were isolated and developed as starters. Comparative studies on different starters for the fermentation of sweet potato for 48 h were investigated. The microbial count of the starter cultures increased as fermentation period increased from 6.06 to 9.14 cfu/ml, the pH reduced from 5.49 to 3.28 while the total titrable acid increased from 0.001 to 0.04. Amongst the various starters used, the use of the mixed cultures (combination of lactic acid bacteria L201 and yeast 601A) as starter cultures in the fermentation of sweet potato for 48 h had the best attributes in terms of texture, flavour, rate of fermentation and consistency when prepared as meal (bolus). The mineral analysis showed that most of the mineral content in the sample increased after fermentation for calcium (Ca) 2043.9 to 2177.5 ppm and Mn 6.29 to 26.32 ppm. The functional properties of the fermented sweet potato flour produced showed moisture content of 10.42%, water absorption capacity of 1.77 g/g and swelling capacity of 86.67%.

Evaluation of starter culture fermented sweet potato flour using FTIR spectra and GCMS Chromatogram

“…After this period has elapsed, the fermented chips were drained and dried in a cabinet drier (Mitchel, Model SM220H) at 55°C for 9 h and milled into flour (≤ 250 μm) using the method of Ajayi et al (2016) and the starter culture fermented sweet potato flour was produced.…”

“…Starter cultures are cheaply reproducible in large amount; they also help provide desirable sensory properties and assist in reducing fermentation period. Ajayi et al (2016) have done work on the fermentation of sweet potato into flour using starter culture.…”

Colour Profile, Pasting and Sensory Properties of Processed Sweet Potato Flour

“…Sweet potato is also an excellent source of vitamin A (14187 IU/100 g) and it is highly nutritious in terms of vitamin C (2.4 mg/100 g), calcium (30 mg/100 g) and iron which is required for adequate energy (0.61 mg/100 g) and magnesium (25 mg/100 g) [6,7]. Despite its high carbohydrate content, sweet potato has a low glycemic index due to low digestibility of the starch making it suitable for diabetic or overweighed people [8,9,10,11,1].…”

“…Starter cultures are preparation or material containing large numbers of variable microorganisms, which may be added to accelerate a fermentation process [18,19]. They help to elicit specific changes in the chemical composition, nutritional value and sensorial properties of the substrate [7,20]. Moreover starter cultures help to reduce fermentation period [21], improve nutritional qualities of food [22] and provide consistency and reliability of performance [23].…”

“…Moreover starter cultures help to reduce fermentation period [21], improve nutritional qualities of food [22] and provide consistency and reliability of performance [23]. Other functions of starter cultures may include the following: flavour, aroma, and alcohol production [7]. Starter cultures can be single (one selected strain of particular species of microorganism) or mixed cultures (two or more strains from a species and/or of different families and genera) with definite characteristics that are beneficial in the manufacture of a desired product [24].…”