Review of knowledge to guide product development and breeding for sweetpotato frying quality in West Africa

This review provides background about sweetpotato in West Africa to identify the current importance and future potential of sweetpotato fried products in the region. We drew on global literature to consider current best practices and health aspects in addition to information from West Africa where frying in the form of large wedges or ‘chunk fries’ is predominant over other forms (i.e. chips (often referred to as crisps in England and the Commonwealth) and ‘French fries’). Chunk fries are produced mostly by female-run microenterprises selling them as a filling snack to roadside and market customers. Boiling, drying and reconstituting in various foods, pounding and consumption of leaves as a vegetable are also important in the region. Further research will inform the development of a product profile for chunk fried sweetpotato and inform breeding strategies to improve sweetpotato for frying and other uses.     

Boiled yam end-user preferences and implications for trait evaluation

This study aimed to establish the quality characteristics of raw and boiled yam by involving stakeholders along the food chain using a methodology that includes a state of knowledge review, focus group discussion and individual interviews, participatory processing diagnosis with processors and consumer testing. Predictive characteristics of yam for producing a high- and low-quality boiled yam were related to morphological or physicochemical characteristics: peeled yam discoloration and mucilage content being negatively appreciated while the ease of peeling, viscous state of cooking water and the ease of breaking yam into pieces positively valued. High-quality boiled yam should be white or yellowish, sticky to the fingers, nonfibrous, easy to chew, crumbly/friable, with a sweet taste and a good smell. The overall liking of boiled yam is greatly penalised by a too dark colour, hard to the touch, no sweet taste and no friability while eating.     

Development of a food product profile for boiled and steamed sweetpotato in Uganda for effective breeding

This study sought to understand user preferences of raw, boiled and steamed sweetpotato, a staple food in Uganda. A sequential methodology involving state of knowledge review, gendered food mapping, processing diagnosis and consumer testing was used in Lira and Kamwenge districts. Preferred raw sweetpotato characteristics were large roots (≥ 3 cm diameter) with a sweet taste, smooth skin and hard texture, while mealiness, sweet taste and good sweetpotato smell were important attributes for boiled sweetpotato. Processors, mostly women, highlighted ease of peeling and sappiness of raw roots. There were gender differences in quality characteristic preferences and perceived importance. The released variety, NASPOT 8, had the highest overall liking in Kamwenge and was well liked in Lira. Penalty analysis of consumer data showed that sweetness and firmness were key drivers of overall liking. The results will support breeding programmes in meeting specific end-user product profiles, selection criteria and uptake of new varieties.     

The use of sensory evaluation and consumer preference for the selection of sweetpotato cultivars in East Africa

Sweetpotato is an important staple crop in East Africa with great potential for introducing improved cultivars, but little is known about which sensory characteristics are desirable. Over a 2 year period, 600 consumers were interviewed at three locations (urban and rural) in the Lake Zone of Tanzania and their preference of 14 locally available sweetpotato cultivars in cooked form was evaluated. A simple questionnaire based on consumers first‐choice preference was used followed by socio‐economic questions. A trained sensory panel profiled the cooked sweetpotato samples, enabling comparisons with preference, location and season. Cluster analysis based on the sensory attributes was used to classify the cultivars into three groups; one cluster comprised the most preferred cultivars and another contained the least. Some cultivars were consistently preferred over the 2 year period while others were not. The location where the cultivars were grown also influenced preference. Stepwise regression indicated that the most discriminating sensory attributes were starch and stickiness. Target levels based on the mean intensity scores of these attributes are suggested as a means of screening new cultivars. The implications of these findings are discussed. Copyright © 2004 Society of Chemical Industry     

A review of varietal change in roots,tubers and bananas: consumer preferences and other drivers of adoption and implications for breeding

This review of the literature on varietal change in sub-Saharan Africa looks in detail at adoption of new varieties of bananas in Uganda, cassava in Nigeria, potato in Kenya, sweetpotato in Uganda and yams in Côte d’Ivoire. The review explored three hypotheses about drivers of varietal change. There was a strong confirmation for the hypothesis that insufficient priority given to consumer-preferred traits by breeding programmes contributes to the limited uptake of modern varieties (MVs) and low varietal turnover. Lack of evidence meant the second hypothesis of insufficient attention to understanding and responding to gender differences in consumer preferences for quality and post-harvest traits was unresolved. The evidence on the third hypothesis about the informal seed system contributing to slow uptake of MVs was mixed. In some cases, the informal system has contributed to rapid uptake of MVs, but often it appears to be a barrier with inconsistent varietal naming a major challenge.     

A review of cassava semolina (gari and eba) end-user preferences and implications for varietal trait evaluation

The purpose of this review is to support breeders and food scientists by examining research carried out on end-user preferences for gari and its derived dough product, eba, in Africa. The review focused on gari regarding the physical and chemical composition of raw cassava roots, methods of storage, the composition of gari with or without enrichment, and the sensory evaluation of gari and eba. The primary sensory attributes identified to describe gari are colour, taste, texture, aroma and flavour. Texture attribute of importance is crispiness for uncooked gari, and hand feel before consumption for eba. There was a significant correlation between the sensory characteristics of gari and the starch and cyanogenic potential (CNP) contents of the raw roots. Hence, the correlation of the end-user preferences with the chemical composition of the cassava roots could be helpful to breeders in refining selection criteria and developing high-throughput screening methods.     

Quantitative trait loci identified for foliar phylloxera resistance in a hybrid grape population

Background and Aims

A hybrid grapevine biparental mapping population was evaluated for resistance to grape phylloxera (Daktulosphaira vitifoliae Fitch) in the greenhouse and in the field. The family (n = 125) was derived from a cross of two University of Minnesota breeding selections from a complex pedigree with multiple Vitis species.

Methods and Results

The vines were evaluated for foliar phylloxera severity using visual rating in the field for multiple years. In the greenhouse, a replicated experimental design was used to quantify phylloxera severity using different traits including number of galls per plant, area under the disease progress curve, proportion of leaves with galls, average number of galls per leaf and visual rating. The plants used in the greenhouse experiment were also visually rated for root infestation.

Conclusions

Quantitative trait loci (QTL) mapping for the foliar resistance traits (reduced severity) routinely identified the region spanning ~10 to 30 cM on linkage group (LG) 14 to be associated with resistance, and inherited from the mother parent MN1264. The plants used in the greenhouse experiment were also visually rated for root infestation, and subsequent QTL mapping identified regions on LG 5 of the maternal map and LG 10 of the paternal map (MN1246) associated with root resistance.

Significance of the Study

The new QTLs identified in this report are potential novel sources of resistance and the first report of QTL for foliar phylloxera resistance in a hybrid grapegrowing region of North America. Molecular markers linked to resistance can be utilised in marker‐assisted breeding.     

A Novel Technique for Limitation of Acrylamide Formation in Fried and Baked Corn Chips and in French Fries

ABSTRACT: The effects of lowering pH by an acidulant (citric acid) on the formation of acrylamide in fried and baked corn chips and in french fries were studied by using a GC/MS. The 0.2% citric acid treatments induced 82.2% and 72.8% inhibition of acrylamide formation in fried and baked corn chips, respectively. Dipping potato cuts in 1% and 2% citric acid solutions for 1 h before frying showed 73.1% and 79.7% inhibition of acrylamide formation in french fries. In the experiment of heating 1 mL solution containing asparagine and glucose in phosphate buffers, by lowering the pH from 7.0 to 4.0, 99.1% inhibition of acrylamide formation was achieved. This is the first finding of an effective, simple, and practical way to limit the acrylamide formation in real foods.     

End-user preferences for pounded yam and implications for food product profile development

Pounded yam is a popular food in Nigeria. This study reports end-user preferences for pounded yam and implications for trait evaluation by breeding programme. The study was carried out in two pounded yam-consuming regions in Nigeria: south-east and south-west. Multistage sampling technique was used to collect information from users along food chain. This involved market, individual, key informant interviews and focus group discussions. Responses of participants were used to develop product profile of pounded yam from raw material (yam) to final product. Key user-preferred quality traits for pounded yam in both regions were colour and textural quality followed by taste and aroma which are lesser attributes. There were regional differences in ranking of these quality attributes but no gender difference. This information will be useful in determining food quality indicators that can be used to select breeding lines for preferred quality traits in pounded yam.     

From cassava to gari: mapping of quality characteristics and end-user preferences in Cameroon and Nigeria

User’s preferences of cassava and cassava products along the value chain are supported by specific root quality characteristics that can be linked to root traits. Therefore, providing an evidence base of user preferred characteristics along the value chain can help in the functional choice of cassava varieties. In this respect, the present paper presents the results from focus group discussions and individual interviews on user preferred quality characteristics of raw cassava roots and the derived product, gari, – one of the major cassava products in Sub-Saharan Africa – in major production and consumption areas of Cameroon and Nigeria. Choice of cassava varieties for farming is mainly determined by the multiple end uses of the roots, their agricultural yield and the processing determinants of roots that support their major high-quality characteristics: size, density, low water content, maturity, colour and safety. Processing of cassava roots into gari goes through different technological variants leading to a gari whose high-quality characteristics are dryness, colour, shiny/attractive appearance, uniform granules and taste. Eba, the major consumption form of gari in Cameroon and Nigeria, is mainly characterised by its textural properties: smoothness, firmness, stickiness, elasticity and mouldability. Recommendations are made, suggesting that breeding will have to start evaluating cassava clones for brightness/shininess, as well as textural properties such as mouldability and elasticity of cassava food products, for the purpose of supporting decision-making by breeders and the development of high-throughput selection methods of cassava varieties. Women are identified as important beneficiaries of such initiatives giving their disadvantaged position and their prominent role in cassava processing and marketing of gari.     

Construction of a solar drying unit suitable for conservation of food and enhancement of food security in West Africa

Drying is a widely used technique in sub-Saharan Africa which allows food conservation, weight reduction and added value for some products. However, the technique is quite complex, making the rational concept of drying devices challenging. A rational method for the design and the construction of a fruit and vegetable solar dryer is presented. A prototype was designed and constructed at the Université Libre de Bruxelles (Belgium) to test the concept and was found to be capable of drying more than 40 kg of fresh tomatoes in 10 h. A second prototype was constructed in Bandiagara (Mali) by both local craftsmen and students from the Université Libre de Bruxelles, using local materials. Speed of drying and prevention of food spoilage was far superior to that of traditional solar dryers. Based on these prototypes, a dryer industry is being constructed in Bandiagara in order to increase food self-sufficiency.     

Economic evaluation of progeny-testing and genomic selection schemes for small-sized nucleus dairy cattle breeding programs in developing countries

In developing countries minimal and erratic performance and pedigree recording impede implementation of large-sized breeding programs. Small-sized nucleus programs offer an alternative but rely on their economic performance for their viability. We investigated the economic performance of 2 alternative small-sized dairy nucleus programs [i.e., progeny testing (PT) and genomic selection (GS)] over a 20-yr investment period. The nucleus was made up of 453 male and 360 female animals distributed in 8 non-overlapping age classes. Each year 10 active sires and 100 elite dams were selected. Populations of commercial recorded cows (CRC) of sizes 12,592 and 25,184 were used to produce test daughters in PT or to create a reference population in GS, respectively. Economic performance was defined as gross margins, calculated as discounted revenues minus discounted costs following a single generation of selection. Revenues were calculated as cumulative discounted expressions (CDE, kg) × 0.32 (€/kg of milk) × 100,000 (size commercial population). Genetic superiorities, deterministically simulated using pseudo-BLUP index and CDE, were determined using gene flow. Costs were for one generation of selection. Results show that GS schemes had higher cumulated genetic gain in the commercial cow population and higher gross margins compared with PT schemes. Gross margins were between 3.2- and 5.2-fold higher for GS, depending on size of the CRC population. The increase in gross margin was mostly due to a decreased generation interval and lower running costs in GS schemes. In PT schemes many bulls are culled before selection. We therefore also compared 2 schemes in which semen was stored instead of keeping live bulls. As expected, semen storage resulted in an increase in gross margins in PT schemes, but gross margins remained lower than those of GS schemes. We conclude that implementation of small-sized GS breeding schemes can be economically viable for developing countries.     

Estimating variance components and breeding values for number of oocytes and number of embryos in dairy cattle using a single-step genomic evaluation

Reproductive technologies such as multiple ovulation and embryo transfer (MOET) and ovum pick-up (OPU) accelerate genetic improvement in dairy breeding schemes. To enhance the efficiency of embryo production, breeding values for traits such as number of oocytes (NoO) and number of MOET embryos (NoM) can help in selection of donors with high MOET or OPU efficiency. The aim of this study was therefore to estimate variance components and (genomic) breeding values for NoO and NoM based on Dutch Holstein data. Furthermore, a 10-fold cross-validation was carried out to assess the accuracy of pedigree and genomic breeding values for NoO and NoM. For NoO, 40,734 OPU sessions between 1993 and 2015 were analyzed. These OPU sessions originated from 2,543 donors, from which 1,144 were genotyped. For NoM, 35,695 sessions between 1994 and 2015 were analyzed. These MOET sessions originated from 13,868 donors, from which 3,716 were genotyped. Analyses were done using only pedigree information and using a single-step genomic BLUP (ssGBLUP) approach combining genomic information and pedigree information. Heritabilities were very similar based on pedigree information or based on ssGBLUP [i.e., 0.32 (standard error = 0.03) for NoO and 0.21 (standard error = 0.01) for NoM with pedigree, 0.31 (standard error = 0.03) for NoO, and 0.22 (standard error = 0.01) for NoM with ssGBLUP]. For animals without their own information as mimicked in the cross-validation, the accuracy of pedigree-based breeding values was 0.46 for NoO and NoM. The accuracies of genomic breeding values from ssGBLUP were 0.54 for NoO and 0.52 for NoM. These results show that including genomic information increases the accuracies. These moderate accuracies in combination with a large genetic variance show good opportunities for selection of potential bull dams.     

植物基仿肉类食品纤维结构设计与评价研究进展

为了减少动物性蛋白食品生产过程对环境的影响,新近开发出的一系列与肉类产品具有相似感官特征的植物基仿肉类食品成为了食品行业的研究热点。本文分析了植物基仿肉类食品快速发展的原因,聚焦于影响这类食品感官品质的关键性因素—纤维结构设计,总结了植物基仿肉类食品纤维结构设计的相关工艺研究进展,介绍了产品纤维结构评价方法。在此基础上,建议我国植物基仿肉类食品的开发要在结合国外优秀技术经验的同时保持中式特色,创新适用于中式烹饪的"仿鲜肉"产品;此外,还应进一步加大对植物基仿肉类食品加工技术中瓶颈问题的研究力度,完善相关标准,加强安全监管,构建具有中国特色的植物基仿肉类食品生产加工体系,促进我国植物基食品新品类的蓬勃发展。     

Selection of indigenous Saccharomyces cerevisiae strains for Nero d'Avola wine and evaluation of selected starter implantation in pilot fermentation

The present research studied Saccharomyces cerevisiae yeasts isolated from Nero d'Avola grapes, collected in different areas of the Sicily region. RAPD-PCR analysis with M13 primer was used for preliminary discrimination among 341 S. cerevisiae isolates. Inoculated fermentations with S. cerevisiae strains, exhibiting different RAPD-PCR fingerprinting, revealed the impact of selected strains on volatile compound concentration. Two selected strains were used in fermentation at cellar level and the restriction analysis of mtDNA on yeast colonies isolated during fermentation was used to control strain implantation. This study represents an important step to establish a collection of indigenous S. cerevisiae strains isolated from a unique environment, such as Nero d'Avola vineyards. Different starter implantation throughout inoculated fermentation represents an additional character, which might be considered during the selection program for wine starter cultures.     

Preliminary selection for potential probiotic Bifidobacterium isolated from subjects of different Chinese ethnic groups and evaluation of their fermentation and storage characteristics in bovine milk

A total of 29 strains of Bifidobacterium were isolated from 18 samples of human feces in different ethnic minority regions of China. All isolates were identified as Bifidobacterium longum (9 strains) and Bifidobacterium pseudocatenulatum (20 strains) based on 16S rRNA gene sequencing and phylogenetic analysis. These strains were preliminarily tested for their suitability to become probiotics by assessing their ability to survive adequately at low pH conditions and their tolerance of different concentrations of bile salts and simulated gastrointestinal juices. In vitro tests were sequentially used to predict the survival of these strains in the simulated conditions in the human gastrointestinal tract. These strains were first exposed to pH 2.5 for 3 h, and 7 out of the 29 strains were discriminated from the others by their high survival rates. Out of these 7 strains, 4 were found to grow and survive well at an even lower pH of 2.0 and in high bile salt concentration. Apart from the gastrointestinal survival capacity, both fermentation efficiency and storage characteristics are important criteria for selecting for suitable potential probiotic strains. Therefore, the fermentation efficiency in bovine milk and the bacterial viability during the storage in the resultant fermented milk were also evaluated for these 4 selected strains. In this study, we isolated and identified 29 novel Bifidobacterium strains. Based on our initial evaluation, at least 4 of them may serve as valuable resources for further dairy probiotic strain selection.