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Roots, tubers and bananas (RTBs) contribute immensely to food security and livelihoods in sub-Saharan Africa, Asia and Latin America. The adoption of RTB genotypes in these regions relies on the interplay among agronomic traits, ease of processing and consumer preference. In breeding RTBs, until recently little attention was accorded key textural traits preferred by consumers. Moreover, a lack of standard, discriminant, repeatable protocols that can be used to measure the textural traits deter linkages between breeding better RTB genotypes and end user/consumer preferences. RTB products texture – that is, behaviour of RTB food products under unique deformations, such as disintegration and the flow of a food under force – is a critical component of these preferences. The preferences consumers have for certain product texture can be evaluated from expert sensory panel and consumer surveys, which are useful tools in setting thresholds for textural traits, and inform breeders on what to improve in the quality of RTBs. Textural characterization of RTBs under standard operating procedures (SOPs) is important in ensuring the standardization of texture measurement conditions, predictability of textural quality of RTBs, and ultimately definition of RTB food product profiles. This paper reviews current SOPs for the textural characterization of RTBs, including their various associated methods, parameters, challenges and merits. Case studies of texture characterized during development of SOPs and evaluation of texture of RTB populations are discussed, together with insights into key textural attributes and correlations between instrumental, sensory and consumer assessment of texture unique to various RTB food products. Hardness was considered a universal key textural attribute to discriminate RTBs. The review should provide adequate insight into texture of RTB food products and critical factors in their measurement. It aims to promote inclusion of texture in breeding pipelines

BACKGROUND: Consumer preferences for boiled or fried pieces of roots, tubers and bananas (RTBs) are mainly related to their texture. Different raw and cooked RTBs were physiochemically characterized to determine the effect of biochemical components on their cooking properties. RESULTS: Firmness in boiled sweetpotato increases with sugar and amylose contents but no significant correlation was observed between other physicochemical characteristics and cooking behaviour. Hardness of boiled yam can be predicted by dry matter (DM) and galacturonic acid (GalA) levels. For cassava, no significant correlation was found between textural properties of boiled roots and DM, but amylose and Ca2+ content were correlated with firmness, negatively and positively, respectively. Water absorption of cassava root pieces boiled in calcium chloride solutions was much lower, providing indirect evidence that pectins are involved in determining cooking quality. A highly positive correlation between textural attributes and DM was observed for fried plantain, but no significant correlation was found with GalA, although frying slightly reduced GalA. CONCLUSION: The effect of main components on texture after cooking differs for the various RTBs. The effect of global DM and major components (i.e. starch, amylose) is prominent for yam, plantain and sweetpotato. Pectins also play an important role on the texture of boiled yam and play a prominent role for cassava through interaction with Ca2+.

BACKGROUND: Potato varieties have diverse biophysical characteristics, so it is important for breeders to have the capacity to choose those that meet the preferences of end users, such as mealiness, firmness, and taste, among others. Combining user preferences with descriptive information regarding the sensory characteristics of boiled potatoes can contribute to the improvement of consumer-driven varieties. This study aimed to factor in the preferences of end users to improve the prospects for varietal acceptance, adoption, and discrimination among genotypes in potato breeding. RESULTS: The priority quality traits (traits that play the most significant roles in acceptance and adoption) of the boiled potatoes were determined by evaluating gender and livelihood using the G+ tool. The G+ tool is designed to assess gender impact on roots, tubers and bananas (RTB) traits by serving as a validation check to reflect on important gender-based issues in agricultural food systems in order to reduce harm and promote positive impact. Potato genotypes were differentiated by penetration (textural parameters as measured by standard texture probe) and the procedure was repeatable, as there was no significant difference between the cooking replicates at 40 min of cooking. Instrument-based texture parameters, such as penetration peak force (hardness/firmness) and area (area under the curve, which represents energy needed to penetrate) of boiled potato tubers were significantly associated with sensory attributes such as fracturability and hardness in the mouth. An attempt to differentiate genotypes using near-infrared spectroscopy (NIRS) revealed that the average results observed for the calibration for yellow color (r2 = 0.70), homogeneity of color (r2 = 0.48), moisture in mass (r2 = 0.40), and uniformity of texture (r2 = 0.56) suggested that these parameters could be used for initial breeding screening purposes. CONCLUSIONS: The preferred traits of the boiled potato can be integrate

BACKGROUND: Previously, a lexicon and protocol for quantitative descriptive analysis (QDA) was established for the Uganda sweetpotato breeding program. The implication of QDA scores for priority sensory attributes on consumer preference should be determined to interpret results efficiently and make decisions effectively. The present study aimed to develop a gender-responsive decision tree to obtain an overall sweetpotato eating quality score to facilitate demand-led targeted breeding selection. It focused on Kamuli and Hoima districts (Uganda) and uses pre-lease advanced clones ('NKB3', 'NKB105', 'NKB135', 'D11' and 'D20'), released varieties ('NASPOT 8' and 'NAROSPOT 1') and landraces ('Muwulu-Aduduma', 'Umbrella'). RESULTS: Including boiled sweetpotato sensory characteristics, namely mealy, sweet taste, sweetpotato smell, firm and not fibrous, in breeding design would benefit end-users, especially women given their role in varietal selection, food preparation and marketing. 'D20', 'NASPOT 8' and 'NAROSPOT 1' were most liked in both districts. 'NKB3' and 'D11' were the least liked in Hoima, whereas 'Muwulu-Aduduma' was the least liked in Kamuli. There was a positive correlation between color and overall liking (r2 = 0.8) and consumers liked the color (average rating ≥ 6 on a nine-point hedonic scale) of all genotypes. Threshold values (average rating on 11-point scales) for consumer acceptability were identified (sweet taste = 6, sweetpotato aroma and flavor = 6, firmness = 3, and mealiness = 4). A regression decision tree tool was created to calculate an eating quality selection index when screening lines in breeding programs using the values. CONCLUSION: Decision trees that include consumer needs and gender considerations would facilitate demand-led breeding and make varietal selection in sweetpotato breeding programs more effective.

The 5-year project 'Breeding roots, tubers and banana products for end user preferences' (RTBfoods) focused on collecting consumers' preferences on 12 food products to guide breeding programmes. It involved multidisciplinary teams from Africa, Latin America, and Europe. Diverse data types were generated on preferred qualities of users (farmers, family and entrepreneurial processors, traders or retailers, and consumers). Country-based target product profiles were produced with a comprehensive market analysis, disaggregating gender's role and preferences, providing prioritised lists of traits for the development of new plant varieties. We describe the approach taken to create, in the roots, tubers, and banana breeding databases, a centralised and meaningful open access to sensory information on food products and genotypes. Biochemical, instrumental textural, and sensory analysis data are then directly connected to the specific plant record while user survey data, bearing personal information, were analysed, anonymised, and uploaded in a repository. Names and descriptions of food quality traits were added into the Crop Ontology for labelling data in the databases, along with the various methods of measurement used by the project. The development and application of standard operating procedures, data templates, and adapted trait ontologies improved the data quality and its format, enabling the linking of these to the plant material studied when uploaded in the breeding databases or in repositories. Some modifications to the database model were necessary to accommodate the food sensory traits and sensory panel trials.

BACKGROUND: The assessment of user acceptability in relation to crop quality traits should be a full part of breeding selection programs. Our methodology is based on a combination of sensory approaches aiming to evaluate the sensory characteristics and user acceptability of root, tuber and banana (RTB) varieties. RESULTS: The four-stepped approach links sensory characteristics to physicochemical properties and end-user acceptance. It starts with the development of key quality traits using qualitative approaches (surveys and ranking) and it applies a range of sensory tests such as Quantitative Descriptive Analysis with a trained panel, Check-All-That-apply, nine-point hedonic scale and Just-About-Right with consumers. Results obtained on the same samples from the consumer acceptance, sensory testing and physicochemical testing are combined to explore correlations and develop acceptability thresholds. CONCLUSION: A combined qualitative and quantitative approach involving different sensory techniques is necessary to capture sensory acceptance of products from new RTB clones. Some sensory traits can be correlated with physicochemical characteristics and could be evaluated using laboratory instruments (e.g. texture). Other traits (e.g. aroma and mealiness) are more difficult to predict, and the use of a sensory panel is still necessary. For these latter traits, more advanced physicochemical methods that could accelerate the breeding selection through high throughput phenotyping are still to be developed.

The objective of the work was to develop, test and evaluate a color and mealiness classification model based on images of sweetpotato roots. A total of 3018 images were collected from 950 samples from October 2021 to November 2022. The captured image data samples were harvested from several sites, including Namulonge, Arua, Bulindi, Nassari, Serere, Rwebitaba, Iganga, Kabarole, Mbale, Mpigi, Busia, Kamuli, Hoima, Kabale and Kenya. Calibrations were done using reference data collected by a sensory panel. Up to twelve cooked roots per genotype were used for sensory evaluation of traits per session. Calibrations used various linear and non-linear models. Using linear regression, high performances were observed of the calibration for orange color intensity (R2 = 0.92, Mean Squared Error (MSE) =0.58), suggesting that the model is sufficient for field application. For mealiness-by-hand and positive area, the best model has a Mean Absolute Error (MAE) of 2.16 and 9.01 respectively.

A variety of imaging sensors are currently used in research and commercial practices to quantify complex crop traits for breeders. Imaging technology is a fast, non-destructive high-throughput phenotyping tool that has been used widely for accurate acquisition of crop traits on a large scale. The DigiEye is a computer-controlled digital camera system for measuring colour and capturing high-quality repeatable images. The SOP highlights the procedure of calibrating the DigiEye, for accuracy and consistance of results.

Prioritizing sensory attributes and consumer evaluation early in breeding trials to screen for end-user preferred traits could improve adoption rates of released genotypes. In this study, a lexicon and protocol for descriptive sensory analysis (DSA) was established for sweetpotato and used to validate an instrumental texture method for which critical values for consumer preference were set. The study comprised several phases: lexicon development during a 4-day workshop; 3-day intensive panel training; follow-up virtual training, evaluation of 12 advanced genotypes and 101 additional samples from two trials in 2021 by DSA and instrumental texture analysis using TPA double compression; and DSA, instrumental texture analysis and consumer acceptability tests on 7 genotypes in on-farm trials. The established sweetpotato lexicon comprising 27 sensory attributes enabled characterization and differentiation of genotypes by sensory profiles. Significant correlation was found between sensory firmness by hand and mouth with TPA peak positive force (r = 0.695 and r = 0.648, respectively) and positive area (r = 0.748, r = 0.715, respectively). D20, NAROSPOT 1, NASPOT 8, and Umbrella were the most liked genotypes in on-farm trials (overall liking = 7). An average peak positive force of 3700 gf was proposed as a minimum texture value for screening sweetpotato genotypes, since it corresponded with at least 46 % of consumers perceiving sweetpotatoes as just-about-right in firmness and a minimum overall liking of 6 on average. Combining DSA with instrumental texture analysis facilitates efficient screening of genotypes in sweetpotato breeding programs.

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 purpose of this activity was to understand the important quality characteristics of boiled/steamed sweetpotato from the perspective of processors, through participatory processing demonstrations from raw material to finished product. The activity was conducted in Northern (Lira) and Western Uganda (Kamwenge). Preparation of sweetpotato in Lira was by boiling whereas steaming was used in Kamwenge. Good processing characteristics, in both regions, included easy to peel (firm peel, less pulp is lost), firm root, smooth peel and flesh surface while the undesirable ones were difficult to peel (soft peel, more pulp is lost in the process of peeling) and soft root. Average processing yield from peeling to boiled product for Lira varieties was 74.4% while for Kamwenge (steaming) it was 81.5%. In Lira, preferred boiled sweetpotato characteristics were absence of sap, mealiness, sweet taste and good smell of sweetpotato. Processors here disliked boiled sweetpotatoes which were sappy, fibrous, and not sweet and did not have a characteristic smell. In Kamwenge, preferred steamed sweetpotato had a nice colour (yellow, white, whitish on the inside), was mealy, firm, had a sweet taste and good sweetpotato smell. Least preferred characteristics for steamed sweetpotatoes were; pale colour, fibrousness, not sweet and off odour. Overall, in Lira, Otada (local) was the most preferred variety followed by Okonynedo (local) with NASPOT 8 (improved) and Arakaraka (local) jointly ranked third. In Kamwenge, NASPOT 8 (improved) was most preferred, followed by Kiribwamukwe (local), Otandibata (local) and lastly Ndererabaana (local).

The aim of this activity was to establish the essential quality characteristics of boiled potato through participatory processing demonstrations with processors at every step from raw material to final boiled product. The activity was conducted in Central (Rakai) and South Western Uganda (Kabale). Boiled potatoes were prepared similarly by boiling in both Kabale and Rakai. When processing, in both regions, ease of peeling (associated with ease of removing 'eyes'), firmness and tubers which were not watery (low water content) were preferred. Potatoes which were not good for processing were; difficult to peel (deep eyes), watery and soft. Average processing yield from peeling to boiled product for Kabale varieties was 79% while for Rakai it was 68%. In Kabale, the most preferred boiled potato characteristics were firmness, mealiness, good potato taste and smell whereas the least preferred were white colour, too soft, watery, not mealy, lacking good potato taste and smell. Processors in Rakai liked mealiness, firmness, softness and smoothness (in the mouth), good potato taste and smell. The poor characteristics were; not mealy, too soft, watery, hard, no potato taste and smell. Generally, in Kabale, the most preferred variety was Rwangume (NAROPOT 4, improved), followed by Kinigi (local), Kachpot 1 (improved) and Victoria (improved). In Rakai, varietal preference for boiled potato in descending order was; Kasumali (local), Deodeo (NAROPOT 4, improved), Kabale (local) and Victoria (improved).

The purpose of this activity was to understand the important quality characteristics of boiled/steamed sweetpotato from the perspective of processors, through participatory processing demonstrations from raw material to finished product. The activity was conducted in Northern (Lira) and Western Uganda (Kamwenge). Preparation of sweetpotato in Lira was by boiling whereas steaming was used in Kamwenge. Good processing characteristics, in both regions, included easy to peel (firm peel, less pulp is lost), firm root, smooth peel and flesh surface while the undesirable ones were difficult to peel (soft peel, more pulp is lost in the process of peeling) and soft root. Average processing yield from peeling to boiled product for Lira varieties was 74.4% while for Kamwenge (steaming) it was 81.5%. In Lira, preferred boiled sweetpotato characteristics were absence of sap, mealiness, sweet taste and good smell of sweetpotato. Processors here disliked boiled sweetpotatoes which were sappy, fibrous, and not sweet and did not have a characteristic smell. In Kamwenge, preferred steamed sweetpotato had a nice colour (yellow, white, whitish on the inside), was mealy, firm, had a sweet taste and good sweetpotato smell. Least preferred characteristics for steamed sweetpotatoes were; pale colour, fibrousness, not sweet and off odour. Overall, in Lira, Otada (local) was the most preferred variety followed by Okonynedo (local) with NASPOT 8 (improved) and Arakaraka (local) jointly ranked third. In Kamwenge, NASPOT 8 (improved) was most preferred, followed by Kiribwamukwe (local), Otandibata (local) and lastly Ndererabaana (local).

The aim of this activity was to establish the essential quality characteristics of boiled potato through participatory processing demonstrations with processors at every step from raw material to final boiled product. The activity was conducted in Central (Rakai) and South Western Uganda (Kabale). Boiled potatoes were prepared similarly by boiling in both Kabale and Rakai. When processing, in both regions, ease of peeling (associated with ease of removing 'eyes'), firmness and tubers which were not watery (low water content) were preferred. Potatoes which were not good for processing were; difficult to peel (deep eyes), watery and soft. Average processing yield from peeling to boiled product for Kabale varieties was 79% while for Rakai it was 68%. In Kabale, the most preferred boiled potato characteristics were firmness, mealiness, good potato taste and smell whereas the least preferred were white colour, too soft, watery, not mealy, lacking good potato taste and smell. Processors in Rakai liked mealiness, firmness, softness and smoothness (in the mouth), good potato taste and smell. The poor characteristics were; not mealy, too soft, watery, hard, no potato taste and smell. Generally, in Kabale, the most preferred variety was Rwangume (NAROPOT 4, improved), followed by Kinigi (local), Kachpot 1 (improved) and Victoria (improved). In Rakai, varietal preference for boiled potato in descending order was; Kasumali (local), Deodeo (NAROPOT 4, improved), Kabale (local) and Victoria (improved).