Food quality profile of pounded yam and implications for yam breeding

Open Access ArticleBACKGROUND Assessment of the key preferred quality traits in pounded yam, a popularly consumed yam food product in West Africa, is often done through sensory evaluation. Such assessment is time-consuming and results may be biased. Therefore, there is a need to develop objective, high-throughput methods to predict the quality of consumer-preferred traits in pounded yam. This study focused on how key quality traits in pounded yam proposed to yam breeders were determined, measured by biophysical and biochemical methods, in order to shorten the breeding selection cycle through adoption of these methods by breeders. RESULTS Consumer tests and sensory quantitative descriptive analysis (QDA) validated that preferred priority quality traits in pounded yam were related to textural quality (smooth, stretchable, moldable, slightly sticky and moderately hard) and color (white, cream or light yellow). There were significant correlations between sensory textural quality attributes cohesiveness/moldability, hardness, and adhesiveness/stickiness, with textural quality measurements from instrumental texture profile analysis (TPA). Color measurement parameters (L*, a*, and b*) with chromameter agreed with that of sensory evaluation and can replace the sensory panel approach. The smoothness (R2 = 1.00), stickiness (R2 = 1.00), stretchability (R2 = 1.00), hardness (R2 = 0.99), and moldability (R2 = 0.53) of pounded yam samples can be predicted by the starch, amylose, and protein contents of yam tubers estimated by near-infrared spectroscopy. CONCLUSION TPA and Hunter colorimeter can be used as medium-high throughput methods to evaluate the textural quality and color of pounded yam in place of the sensory panelists

Helicobacter pylori strains from a Nigerian cohort show divergent antibiotic resistance rates and a uniform pathogenicity profile

Antibiotic resistance in Helicobacter pylori is a factor preventing its successful eradication. Particularly in developing countries, resistance against commonly used antibiotics is widespread. Here, we present an epidemiological study from Nigeria with 111 isolates. We analyzed the associated disease outcome, and performed a detailed characterization of these isolated strains with respect to their antibiotic susceptibility and their virulence characteristics. Furthermore, statistical analysis was performed on microbiological data as well as patient information and the results of the gastroenterological examination. We found that the variability concerning the production of virulence factors between strains was minimal, with 96.4% of isolates being CagA-positive and 92.8% producing detectable VacA levels. In addition, high frequency of bacterial resistance was observed for metronidazole (99.1%), followed by amoxicillin (33.3%), clarithromycin (14.4%) and tetracycline (4.5%). In conclusion, this study indicated that the infection rate of H. pylori infection within the cohort in the present study was surprisingly low (36.6%). Furthermore, an average gastric pathology was observed by histological grading and bacterial isolates showed a uniform pathogenicity profile while indicating divergent antibiotic resistance rates

Effect of Parboiling on Physico-chemical Qualities of Two Local Rice Varieties in Nigeria

Two varieties of local rice in paddy form were used for this study. The rice were collected from local farmers at Okemesi Ekiti in Ekiti State of Nigeria (western Nigeria). The rice were divided into halves, one half was processed by Parboiling, Drying and Milling, the other half was processed by Drying and Milling only. The result from the study showed that parboiling affected the physico-chemical qualities of the rice varieties. There were differences in the physical dimension, appearance, colour, water absorption, cooking time, amylose, protein, fat and carbohydrate contents of the parboiled and non-parboiled rice samples. Varietal differences also exist between the rice samples. Parboiling reduced the breakage, fat, protein and amylose content of the rice while the cooking time, water uptake and thiamine contents were increased. It can therefore be inferred that parboiling which has been the means of processing rice in Nigeria can be a way of improving vitamin content and milling properties of rice and should attract the interest of food technologists and food processors to develop the rice industry. The Journal of Food Technology in Africa Volume 6 No.4, 2001, pp. 130-13

Physicochemical properties of yam starch: effect on textural quality of yam food product (pounded yam)

Yam (Dioscorea spp.) is the second most important root and tuber crop in Africa after cassava. This study was conducted to determine the relationship between physicochemical properties of yam starch (amylose and amylopectin, swelling, solubility and water binding capacity) and the textural quality (stretchability, cohesiveness, adhesiveness, hardness) of pounded yam, a major food product in West Africa. Yam starch was extracted from six tubers each of Dioscorea alata and D. rotundata and their physicochemical properties were determined by standard methods. Pounded yam was prepared from the same set of tubers. Textural quality evaluation was conducted on the pounded yam samples by sensory texture profiling. Data generated were evaluated by canonical correlation analysis. Results showed that D. rotundata with high swelling power, low amylose and water binding capacity gave pounded yam samples, which were cohesive, stretchable, moderately soft and less sticky compared to D. alata with high amylose, water binding capacity and low swelling power that gave pounded yam samples, which were very soft, unstretchable, sticky and incohesive. Canonical analysis showed significant associations (P<0.05) between the physicochemical properties and textural quality of pounded yam samples. These results from D. rotundata were further validated using eighteen other randomly selected yam varieties from this yam species. The reproducibility of physicochemical parameters for the assessment of food textural quality was established. Thus, they can serve as indicators of food textural quality in the selection of yam for food quality by breeders and processors

Effect of parboiling on physico-chemical qualities of two local rice varieties in Nigeria

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Pasting characteristics of fresh yams (Dioscorea spp.) as indicators of textural quality in a major food product: pounded yam

Low efficiency of available screening procedures constrains breeding and selection of yams (Dioscorea spp.) towards high textural quality of food products made from their tubers. This study was undertaken to determine the potential usefulness of pasting characteristics of fresh yams as rapid indicators of food textural quality in Ô pounded yam Õ, a staple food for millions of yam consumers, especially in West and Central Africa. Significant associations (P< 0.05) were found, through canonical correlation analysis, between pasting characteristics of fresh yams from six varieties, each, of Dioscorea rotundata and Dioscorea alata and the textural quality of pounded yam samples prepared from them. Good textural quality of pounded yam was associated with high peak viscosity, breakdown, final viscosity, holding strength and setback viscosity but with low pasting temperature in the fresh yam