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Consumers of potato in Uganda prefer potato tubers that are soft when cooked. Softness is commonly used as an antonym for firmness. Therefore, consumers like potatoes that require little effort to bite through. This SOP describes laboratory-based methods for measuring instrumental texture in steamed potato. The methods described include details about sample preparation, conditions of instrumental texture analysis and description of textural parameters measured. To cook the samples, cubed pieces measuring 2.5cm on each side were excised from potato tubers and steamed between pieces of banana leaves over boiling water for 15 minutes. A similar procedure is used when preparing potato samples for descriptive sensory analysis where whole tubers are peeled and steamed between layers of banana leaves over boiling water for 40 minutes. The proposed texture analysis procedure is conducted on 2.5 cm cubes of potato using a 60° conical probe to a maximum distance of 10 mm for penetration, 75mm cylindrical plate for two-cycles texture profile analysis (TPA), and 5-blade grid Ottawa cell for extrusion. The methods were validated by comparing with descriptive sensory analysis of steamed potato on the same samples, and significant correlations were found. While all the methods were discriminant, the penetration method seemed to be preferred in lieu of extrusion and texture profile analysis.

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: Yam (Dioscorea alata L.) is the staple food of many populations in the intertropical zone where it is grown. The lack of phenotyping methods for tuber quality hinders the adoption of new genotypes from the breeding programs. Recently, near infrared spectroscopy (NIRS) has been used as a reliable tool to characterize the chemical composition of the yam tuber. However, it failed to predict the amylose content, although this trait is strongly involved in the quality of the product. Results: This study used NIRS to predict the amylose content from 186 yam flour samples. Two calibration methods were developed and validated on an independent dataset: Partial Least Square (PLS) and Convolutional Neural Network (CNN). To evaluate final model performances, the coefficient of determination (R2), the root mean square error (RMSE), and the Ratio of Performance to Deviation (RPD) were calculated using predictions on an independent validation dataset. Tested models showed contrasting performances (i.e. R2 of 0.72 and 0.89, RMSE of 1.33 and 0.81, RPD of 2.13 and 3.49 respectively, for the PLS and the CNN model). Conclusion: According to the quality standard for NIRS model prediction used in food science, the PLS method proved unsuccessful (RPD<3 and R2<0.8) for predicting amylose content from yam flour, while the CNN proved reliable and efficient method. With the application of deep learning method, this study established the proof of concept that amylose content, a key driver of yam textural quality and acceptance, could be predicted accurately using NIRS as a high throughput phenotyping method.

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: Stretchability is the most important sensory textural attribute considered by consumers of pounded yam. It is important both for the processor during pounding and for the consumer during consumption to measure this attribute while screening large populations of yam genotypes intended for advanced breeding and eventual adoption. Texture determined by sensory evaluation and consumer perception is time consuming and expensive. It can be instrumentally mimicked by texture analyser, thereby providing an efficient alternative screening tool. Results: Two instrumental methods (uniaxial extensibility and lubricated squeezing flow) were applied to assess the extensional properties of pounded yam. In order to evaluate the accuracy, repeatability and discrimination of the methods, six yam genotypes with contrasting extensional properties, previously evaluated by 13 panellists in terms of stretchability and moldability and by 99 participants randomly selected in terms of overall liking, were used. Both methods allowed the discrimination of different genotypes as a function of extensional properties. Principal components showed that the genotypes were grouped within separate components associated with specific sensory attributes and their related instrumental texture parameters. Moreover, significant correlations were found between uniaxial extensibility textural attributes, bi-extensional viscosity and consumer overall liking. However, the sensory attributes were not significantly correlated with instrumental data and consumer overall liking. Conclusion: Bi-extensional viscosity and uniaxial extensibility attributes can be used to discriminate and screen yam genotypes for their strechtability characteristics.

BACKGROUND: Boiled yam key quality attributes typical for West African consumers are: crumbly, easy to break, and sweet taste. New yam varieties are being developed but high or medium throughput tools to assess the required quality traits and their range of acceptance are limited. This study assessed the acceptance thresholds of these quality attributes and established the predictive models for screening yam varieties that meet the required consumers' preferences. RESULTS: Overall liking was associated with sweet taste, crumbly and easy to break (r values 0.502, 0.291 and -0.087, respectively). These parameters and selected biophysical parameters highly discriminated the boiled yam varieties. Crumbly texture and easy to break were well-predicted by penetration force and dry matter, whereas sweet taste by dry matter and sugar intensity. A high crumbliness and sweet taste are preferred (sensory scores above 6.19 and 6.22 for crumbly and sweet taste, respectively, on a 10 cm unstructured line scale), while a too high easiness to break is disliked (sensory scores ranging from 4.72 to 7.62). Desirable biophysical targets were between 5.1 and 7.1 N for penetration force, dry matter around 39% and sugar intensity below 3.62 g/100g. Some improved varieties fulfilled the acceptable thresholds, and the screening was improved through the deviation from optimum. CONCLUSION: The acceptance thresholds and the deviation from optimum for boiled yam assessed through the instrumental measurements are promising tools for yam breeders.

The instrumental measurement of extensibility texture (which represents sensory stretchability) may be considered as an important procedure for measuring the quality parameter in selecting yam genotypes for pounded yam. Nineteen alata and rotundata varieties of yams from several Ivorien populations were collected in CNRA Bouake station to determine the baseline characteristics of the yams regarding the pounded yam extensibility. The uniaxial extensibility (UAE) and the bi-extensional viscosity (BEV) of pounded yam was determined by standard operating procedures (SOP) after the pounded yam was prepared following a standard method. The training mission was conducted to train the Centre National de Recherche Agronimique (CNRA) and Université Nangui-Abrogoua (UNA) teams to set up and measure extensibility of pounded yam instrumentally using the texture analyser and standard procedures; uniaxial extensibility and lubricated squeezing flow (LSF). Some Statistical evaluations were presented to show the accuracy, repeatability, and discriminant power of the procedures. Context: Support training on new SOPs to determine the instrumental extensibility texture of pounded yam Content: Instrumental extensibility texture of pounded yam Objectives: To train the partners in the setting up of the texture analyser and determination of extensibility of pounded yam by different protocols - To evaluate the accuracy, repeatability, and discriminability of extensibility texture protocols used to measure instrumental extensibility parameters - To familiarize trainees on techniques for conducting other textural measurement protocols (such as extrusion, penetration, and Texture Profile Analysis, TPA).

The cooking quality of pulses depends essentially on water transfers; they are thermally thin objects. These water transfers are driven by multiple thermal events related to starch (gelatinization, melting) and proteins (denaturations). The objective of this study was to understand the physicochemical processes involved in the cooking of legumes in order to propose technological ways of innovation (facilitating their preparation mode, ready to use...). This study identified, at steady state, the phase changes of starch and protein macronutrients of legumes (lentil, chickpea, bean), using differential scanning calorimetry (DSC) for the separation of thermal events (starch/protein). Modeling by de-summarization of DSC peaks and representation of binary water/starch and water/protein phase diagrams was developed. The combination of these two phase diagrams has made it possible, by adjustment, to represent the behaviour of the ternary water/starch/protein system and to propose a distribution of water between starch/proteins. For example, for chickpeas and beans, the amount of water attributed to the starch increases from less than 10% of the total water to about 35-45% at the end of cooking. The results of this work were able to model the water/starch/protein equilibrium states and will facilitate the representation of dynamic water transfer model in legumes during pre-soaking and cooking.

The stretchability of pounded yam is considered a key textural attribute that is preferred by consumers of pounded yam who regard the attribute as important for accepting the pounded yam as high quality food product. In order to describe the sensory perception of stretchability of pounded yam quantitatively, it is necessary to develop instrumental protocols that can measure the sensory texture reliably. Instrumental extensibility can represent the sensory stretchability of pounded yam. The new SOPs for uniaxial extensibility and bi-extensional viscosity developed for pounded yam at CIRAD was used to determine the extensibility of pounded yam using the texture analyser instrument. The mission was conducted between 4-7 October 2022 to train the BOWEN University, Iwo team to set up the texture analyser and measure bi-extensional viscosity (BEV) of pounded yam using the lubricated squeezing flow (LSF) protocol; and to measure the extensibility of pounded yam using the uniaxial extensibility protocol. After demonstration of the protocols using available genotypes (Kamilu & Ewura), statistical evaluations were presented to inform of the accuracy, repeatability, and discriminability of the protocols. A few challenges were however encountered in the use of the Perten Instruments texture analyser for the measurements. These challenges were not encountered by the use of a Stable microsystems texture analyser at International Institute of Tropical Agriculture (IITA), where the training was eventually concluded. A new version of the software may be a solution. Also accessories adapted to this PERTEN analyser is required.

The stretchability of Eba and pounded yam is a key textural attribute preferred as an acceptable quality parameter by consumers of Eba and pounded yam, respectively. The two new SOPs for determination of uniaxial extensibility and bi-extensional viscosity developed for pounded yam was adapted to determine the extensibility of pounded yam and Eba, respectively, as measured by the texture analyser instrument. The instrumental extensibility parameters will represent the sensory stretchability of Eba and pounded yam. The mission was conducted at International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria between 26-30 September 2022, to train the IITA and the Faculty of Agricultural Sciences, University of Abomey Calavi (FSA-UAC), Benin teams to set up the texture analyser and measure bi-extensional viscosity of Eba using the lubricated squeezing flow (LSF) protocol; and to measure the extensibility of pounded yam using the uniaxial extensibility protocol. Some modifications were introduced in the protocols, specific to the food product profile of Eba, by changing test speed to 12mm/min and biaxial strain to 1.0. Statistical evaluations were presented to inform of the accuracy, repeatability, discriminability and best instrument measurement parameters of the protocols.

The stretchability of fufu is considered as a key textural attribute preferred by consumers of fufu as an acceptable quality parameter. The NRCRI team were trained in Nigeria between 19-23 September, 2022. The new SOP for uniaxial extensibility already developed for pounded yam was considered to determine the extensibility of fufu, while the new SOP for bi-extensional viscosity already developed for pounded yam was adapted to measure the bi-extensional viscosity of fufu using a test speed of 120mm/min and biaxial strain of 1.0. The training was done to determine instrumental extensibility texture of fufu using a texture analyser, which may represents the sensory stretchability of fufu. The mission was conducted to train the National Roots Crop Research Institute (NRCRI) team to set up and measure extensibility of fufu using three protocols; uniaxial extensibility, lubricated squeezing flow (LSF) and Kieffer dough gluten extensibility (KDGE) rig. Some modifications were introduced in the protocols, specific to the food product profile of fufu, and statistical evaluations were presented to show the accuracy, repeatability, and discriminance of the protocols.

Fufu, a fermented wet paste food product from cassava is a good source of dietary energy and is one of the widely consumed foods in Nigeria and other West African countries. In fufu processing, retting involves the steeping of cassava roots in water for a period of 72 hours. Due to the genetic make-up of different cultivars of cassava, there is variation in the retting abilities of these cassava roots. Therefore, it is of importance to standardize the procedure involved in determining the different retting behaviors of these different cassava cultivars using a hand held penetrometer. This SOP encapsulates the materials required for the standardized procedure, as well as the instrument involved. The protocol for evaluating the retting ability of cassava genotypes was standardized using the hand-held penetrometer by measuring firmness of 42 cassava genotypes (37 breeder's elite clones, 3 released elite clones, 2 landraces) with contrasting root quality attributes during various retting regimes. Data obtained showed that the protocol effectively classified the genotypes into three distinct groups: fast (low firmness), intermediate (intermediate firmness) and slow (high firmness) retting groups.

This SOP describes the method for determining the bi-extensional viscosity (BEV) by application of lubricated squeezing flow (LSF) on pounded yam produced from different yam varieties using a texture analyser under fixed conditions. A full description of the sample preparation (pounded yam), conducting the experimental measurements, calculation using the obtained raw data and results expression are proposed. This SOP could be adapted for other pasty products such as Eba, Fufu or Matooke in order to obtain the corresponding bi-extensional viscosity that may be related to other sensory quality traits.

The ease of peeling fresh cassava root has been a major bottle neck which affects productivity of cassava processor in Nigeria and other cassava producing regions in the world. This study involves standardization of the protocol for measuring ease of peeling fresh cassava roots. This document describes the procedure for measuring ease of peel of cassava using root weight, length, circumference, ease of peeling , smoothness of skin, peel thickness, peel weight, and peeling time of different genotypes with different shape (cylindrical, conical and irregular) and size (small, medium and big). These root characteristics determine the ease of peeling cassava roots. The protocol involves evaluation of 3 roots from each different cassava genotype possessing contrasting root quality attributes (geometric characteristics) by three (3) champion processors

Steam-cooked cassava preparation show variations related to the cassava piece size and the cooking mode; this presumably affect the sensory descriptors and texture of final product. In this context, a robust methodology for steam-cooked cassava preparation and texture analyses was established. After washing and cutting the roots in about 5 cm long, each piece is divided in the shape of half cylinder prior to peel, and then washed in tap water before cooking. Ideal cooking time (ICT) defined as fixed cooking duration (45 min) of cassava varieties was determined. The ICT is used to steam the samples which were tested at 45 °C by penetration test, simple compression and extrusion test using conical probe P/40C, compression plate (P/75) and Ottawa cell with 5-blade grid respectively. All methods (penetrometry, compression, extrusion) exhibited clear discrimination between cassava varieties regarding texture parameters.

Pounded yam is a glutinous dough product made from yam tubers often consumed in bolus form along with stews or soups. It is considered a common cuisine in West Africa in countries like Nigeria, Benin, Ghana, Cameroon and Ivory Coast. Often mislabelled as 'fufu' in some cultures, pounded yam is prepared by peeling mature yams, washing, dicing, cooking, and pounding into a uniform consistency. Pounded yam is often preferably made from Dioscorea rotundata varieties of yam, and less often prepared from the Dioscorea alata varieties. This may be associated with the traditional consumer preference for a sufficiently doughy, stretchable, mouldable, and acceptably firm pounded yam. These quality attributes may be measured instrumentally by the use of texture analysers and can be possibly correlated with human sensory perception scores. The standard operating protocol (SOP) for determination of extensibility of pounded yam is based on its viscoelastic property. It measures how extensible the dough is when made into a sheet of about 1.5 mm thickness and a uniaxial force is exerted by a standard P/1SP probe under fixed test conditions. The conditions are: test mode: compression, load module: 5 kg, pre-test speed: 5 mm/s, test speed: 1 mm/s, post-test speed: 10 mm/s, trigger force: 5 g, target mode: distance, Distance: 40 mm. The repeatability of cooking replicates and ANOVA to classify four contrasting yams of varying textural quality were conducted. Correlations between sensory, instrumental, and consumer overall likeability provided relationships between measurable and discernible extensibility of pounded yam.

Qymyz is a traditional acidic and ethanolic beverage in central Asian countries made from mare milk fermentation with lactic acid bacteria (LAB) and yeasts. Modeling the growth of microorganisms during fermentation is one of the methods used to control the quality of fermented products. The objective of the study was, firstly, to model the growth kinetics of Kazachstania unispora found in qymyz, and, secondly, to understand their interaction with Lacticaseibacillus casei and Lactobacillus kefiri during the fermentation of mare milk. The K. unispora optimum values of pH and temperature were 4.81 ± 0.22 and 30.16 ± 0.53 °C, respectively, with an optimal growth rate (µopt) of 0.56 ± 0.02 h−1. K. unispora had an ethanol production rate of 6.1 × 10−8 mg·CFU−1. Growth, in terms of limiting substrates showed a lower Ks value for galactose at 0.13 ± 0.04 mg·mL−1 with µopt of 0.45 ± 0.01 h−1, while, for glucose, the Ks was 0.24 ± 0.03 mg·mL−1 with the same µopt. Cocultures of K. unispora were conducted with L. casei and L. kefiri in a synthetic medium and mare milk. The results showed that K. unispora growth was limited and, thus, its ethanol production capacity was inhibited. VOC analysis of mare milk fermented with the studied strains and their cocultures resulted in 37 major volatile compounds. Statistical analysis of the VOC profiles showed that K. unispora modulates the aroma production in coculture with LAB.