Physico-Chemical and Sensory Evaluation of Cooked Fermented Protein Fortified Cassava (Manihot Esculenta Crantz) Flour
*Corresponding author: Joseph R. Powers
Rosales-Soto MU, Ross CF, Younce F, et al. Physico-chemical and sensory evaluation of cooked fermented protein fortified cassava (Manihot esculenta Crantz) flour. Adv Food Technol Nutr Sci Open J. 2016; 2(1): 9-18. doi: 10.17140/AFTNSOJ-2-126
©2016 Powers JR. This is an open access article distributed under the Creative Commons Attribution 4.0 International License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: The aim of this study was to investigate the effects of fermentation with Lactobacillus plantarum strain 6710, on protein- and pro-vitamin A-fortified and wild type cassava flours for production of cooked fufu.
Results: Physico-chemical analysis of fufu flour and cooked fufu were accomplished. Pasting properties determined that non-inoculated zeolin fortified cassava flour at 0 h of fermentation will cook rapidly due to its low pasting temperature. Volatiles such as acetic acid, hexanal, nonanal and decanal were detected in most samples. A trained sensory panel determined no impact of sample type on cooked fufu aroma.
ILTAB: International Laboratory for Tropical Agricultural Biotechnology; MRS: de Man, Rogosa and Sharpe; BPW: Buffered Peptone Water; RVA: Rapid Visco Analyzer; PDMS/DVB: Polydimethylsiloxane/divinylbenzene; IRB: Institutional Review Board; ANOVA: Analysis of variance; AACC: American Association for Clinical Chemistry.
Over 95% of cassava produced in Nigeria is used for human food. However, a cassava rootbased diet does not provide complete nutrition because it contains 85% starch and only 1-2% protein. Additionally, toxic compounds and rapid deterioration after harvest limit the utilization of unprocessed cassava.1
Fufu is a fermented wet cassava paste that is widely consumed in eastern and southwestern Nigeria and other parts of West Africa. However, fufu consumption has decreased due to inherent odor, short shelf life and tedious preparation.2 Regular fufu is made by fermenting freshly harvested cassava tubers in water in open containers for days and is traditionally sold in the highly perishable wet form.1 The short shelf life is a serious limitation for large-scale processors. A practical approach for improving the shelf life and marketability of fufu is drying, which is aimed at producing reconstitutable fufu dough with physico-chemical characteristics of cooked wet paste.2,3 While several methods have been used for the drying of fufu, it was determined that a rotary dryer provided a more acceptable product compared to cabinet and sun drying methods, even though the rotary drying method was not cost effective.4 In addition, as reported by Sanni et al2 several drying techniques have been reported to reduce the strong odor of fufu, but the products were sticky, bland and the quality unacceptable when reconstituted from flour.
The objectives of this study were to determine the characteristics of protein- and pro-vitamin A-fortified fermented cassava flours with or without the addition of Lactobacillus plantarum strain 6710 and their influence on the processing of cooked fufu. Similar characteristics for cooked fufu from protein- and pro-vitamin A-fortified cassava and the wild type cassava flour may allow consumers to enrich their diets nutritionally without sacrificing the inherent characteristics of commonly consumed cooked fufu.
Results and Discussion
pH and Titratable Acidity
Most naturally fermented samples (NF) reached a minimum pH value at 96 h fermentation compared to 72 h for the L. plantarum samples (LF). NFS and NF SPRO showed a pH value of 4.34 and 4.51 at 96 and 72 h, respectively. A fast decrease to pH 3.60 was observed when the lactic acid bacteria strain was added for LFS and LF SPRO at 96 and 72 h of fermentation, respectively. These results agree with Brauman et al,12 who reported that LAB produced a rapid drop in pH to ~4.5 after two days fermentation of cassava roots.
The fermentation process resulted in a gradual increase of acidity for the non-inoculated wild type (NFWT) and inoculated wild type (LFWT) cooked fufu up to 72 h of fermentation, with no further significant change at 96 h (p>0.05). An analogous tendency was shown for the NFZ and LFZ.
When Lactobacillus plantarum starter culture was added, the decrease in pH and increase in TA occurred more rapidly (24 h) when compared to samples without starter culture. This agrees with Kostinek et al,13 who determined a high capability for the obligate homo- and facultative hetero fermentative group (mostly L. plantarum) to lower the pH of the medium. Acid production and subsequent decrease extends lag phase of sensitive organisms including foodborne pathogens.14
Peak time is a property that indicates the minimum time required for fufu cooking. At 0 h fermentation, significant differences in peak time, that may have developed during the pasting analysis of the samples, were found between all NF and LF individual samples of a given cassava material, i.e. NFWT versus LFWT (p≤0.05) (Table 2), with the exception of NF PRO and LF PRO. At 96 h fermentation, NF and LF treatments were significantly different in peak time for all cassava material pairs (p≤0.05) (Table 2). Peak times were consistently higher for the NF versus LF samples (within a given sample pair). This supported the observation that the decrease of pH or increase of acidity occurs more rapidly when Lactobacillus plantarum starter culture was added. Therefore, it is likely that fermentation in NF samples was focused most prevalently on amorphous regions of starch granules, which caused an increase of peak time and did not allow a more rapid fermentation. The greatest peak time was found for NF SPRO (4.87 min) at 0 h fermentation, which could be related to protein-carotenoid interaction that increased the time to peak viscosity. Such ingredients may increase the peak time if they coat the granule, limiting water penetration and thus, hydration and swelling. Protein-carotene interaction was shown by Marx et al15 when crystalline β-carotene with bovine serum albumin in a model system proved to be stable towards isomerization irrespective of time-temperature parameters which indicated binding as the protein protected the carotenoid.
In addition, NF SPRO showed the lowest breakdown values (Table 2). A similar trend was observed for LF SPRO when compared with all inoculated cassava materials at 0 and 96 h fermentation. Therefore, these fufu flours might be able to withstand heating and shear stress compared to the other samples. At 96 h fermentation, NF SPRO also showed the highest peak time (5.14 min) even though it was not significantly different from NFWT, NFS and NF SPRO. Based on the lowest peak time, NFZ and LFZ at 0 and 96 h of fermentation will cook faster with less energy consumed, thereby saving cost and time compared to other samples. Except for NFZ, peak times for NF samples at 96 h fermentation were slightly higher than the values determined for LF samples. This may be due to the conversion of starch to simple sugars due to fermentation by the microorganisms causing a decrease of the stability of the starch materials.16
Prior to fermentation, the mean peak viscosity was greatest for NFZ fufu flour (5969 cP) as opposed to NF SPRO (3328 cP). A similar relationship was observed for LFZ and LF SPRO cassava materials (Table 2). This observation might have been influenced by greater or more rapid swelling of starch granules in NFZ, which in turn may cause instability and consequently disruption upon the heating and stirring (i.e., breakdown). Furthermore, the final viscosity and pasting temperature of NFZ flour were substantially lower, likely due to free leaching of amylose and amylopectin from the granules.17 Thus, it would
This study showed that it is possible to make a product similar to cooked fufu with protein and/or pro-vitamin A fortified cassava flours inoculated with Lactobacillus plantarum.