Sensory perception of bitterness and astringency in sorghum

There is a conflict of interest between the sorghum producers, for whom condensed tannins in sorghum have agronomic advantages, and sorghum users for whom condensed tannins in sorghum are perceived as nutritionally harmful and unpalatable. However, in recent years there has been growing interest in food phenolics due to their antioxidant potential. Thus, enhancing the content of phenolic compounds in plant foods through selective breeding and/or genetic improvement is now being viewed as a potent dietary option for disease prevention and control. However, the objectionable sensory attributes (bitterness and astringency) of phenolic compounds, especially condensed tannins, have resulted in low consumption of foods rich in these compounds. This study investigated the sensory attributes of products of sorghums varying in total phenol and condensed tannin content as well as their acceptance. A descriptive sensory panel described the sensory attributes including bitterness and astringency of two products, sorghum rice and bran infusions of six sorghum cultivars: three containing tannins and three with no detectable tannins. The products of all the sorghums (tannin and tannin-free) were perceived to different degrees as both bitter and astringent. The products of sorghums with the highest total phenol and tannin content were most bitter and astringent while those from tannin-free sorghums with the lowest total phenol content were least bitter and astringent. The products of NS 5511 (tannins - 1.8% catechin equivalents CE), were perceived similar in both bitterness and astringency to those of a tannin-free sorghum (PAN 8564). Using the Dual Attribute Time Intensity (DATI) sensory method the descriptive sensory panel determined the intensity and time course of bitterness and astringency of bran infusions of sorghums varying in total phenol and condensed tannin content. The infusion from the sorghum with the highest condensed tannin content (PAN 3860) was perceived as most bitter and most astringent and that from the tannin-free sorghum with the least total phenol content (Phofu) was least bitter and astringent. Bitterness of the sorghum infusions developed and reached maximum intensity significantly faster than astringency. The total duration of the astringency sensation lasted significantly longer than bitterness. The more bitter and more astringent the sorghum was, the longer the persistence of the bitter and astringent after-taste. The infusion of NS 5511 was again perceived similar to tannin-free sorghums in both bitterness and astringency. These findings seem to suggest that there is a condensed tannin threshold level at which the tannins are not ‘strongly’ perceived and thus are not objectionable. A consumer panel classified by 6-n-propylthiouracil (PROP) taster status assessed the colour, texture, flavour and overall liking of sorghum rice of two tannin-containing (tannin) sorghums and two tannin-free sorghums. The sorghum rice from PAN 3860, with the highest tannin content, received significantly lower acceptance ratings for all the sensory attributes than the other sorghums. With the exception of appearance, the acceptance of the sorghum rice from the tannin sorghum NS 5511 was not significantly different from that of the two tannin-free sorghums. The PROP tasters (medium and super) could distinguish differences among the sorghum cultivars varying in tannin content levels which presumably led to the significant difference in their acceptance ratings for the most bitter and astringent sorghum compared to others. On the other hand the non tasters preferred the cultivars equally, presumably because they could not detect taste differences (in bitterness and astringency) between the sorghum cultivars. The results of the consumer panel confirm the predictions made from the descriptive sensory panel results that not all the tannin sorghum products would be objectionable to consumers. It is proposed that the condensed tannin threshold level is 2.0% CE inclusive of the tannin content level of NS 5511 (1.8% CE). It is recommended that future breeding programmes investigate production of sorghums like NS 5511 with condensed tannin levels that fall within this threshold limit. The level of condensed tannins in these sorghums would provide the agronomic advantages for the farmer by reducing pre-harvest and post-harvest losses as well as provide the antioxidant benefits associated with them without negatively affecting the nutritional value of the food/feed. Since the negative sensory properties of these sorghums are not strongly perceived they would not be objectionable to consumers, thus making them a promising health option for millions of people.Thesis (PhD)--University of Pretoria, 2009.Food Scienceunrestricte

Application of the dual attribute time-intensity (DATI) sensory method to the temporal measurement of bitterness and astringency in sorghum

Bitterness and astringency are attributes generally cited as the cause of tannin sorghums being unpalatable. The objective here was to determine the effect of sorghums with varying tannin content on bitterness and astringency simultaneously using dual attribute time-intensity (DATI). A trained panel assessed bitterness and astringency of bran infusions of tannin and tannin-free sorghums. In both sorghum types, bitterness developed and reached maximum intensity faster (Tmax 22.5 s; P < 0.001) than astringency (27.9 s). The duration of the astringent sensation (Dtot 69.9 s) lasted longer than bitterness (66.3 s). Overall, the temporal parameters for bitterness distinguished infusions from tannin and tannin-free sorghums slightly more clearly than those for astringency. The research established that, for sorghum, bitterness and astringency are related. The DATI method also revealed that panellists’ perceptions of the time course of bitterness and astringency differ.The South African National Research Foundationhttp://onlinelibrary.wiley.co

An alternative food neophobia scale (FNS-A) to quantify responses to new foods

An alternative Food Neophobia Scale (FNS-A) was developed in three studies to measure food neophobia (reluctance to eat and avoidance of trying new foods). In Study 1, the original food neophobia scale, FNS (Pliner, & Hobden, 1992), was first critically examined leading to modifications in five and omission of two statements. Furthermore, eight positive and eight negative statements were elicited and introduced along with eight original or modified FNS statements to 575 respondents in South Africa, Lesotho, and Botswana. Study 2 (n = 1010) was used to confirm the factorial structure of the scale, and Study 3 (n = 141) was used to test the reliability of FNS-A through test-retest data. The structure of the scale was analyzed using exploratory (Study 1 and 2) and confirmatory (Study 2) factor analysis, eventually leading to four positive and four negative statements regarding new foods, loaded on two factors labelled approach and avoidance. Test-retest reliability at a 2 weeks' time interval as well as convergent and divergent validity measured against other scales was good (Study 3). In all three studies, predictive validity was evaluated against willingness to try or expected liking ratings of unfamiliar or novel food names or food concept descriptions. This evaluation showed satisfactory performance. FNS-A is a promising tool for the quantification of individual responses to unfamiliar or novel foods, but further studies in other populations and contexts are needed to confirm the applicability.Peer reviewe

Effects of Bambara groundnut and butternut blend on proximate, mineral, beta-carotene and folic acid contents of sorghum flour

The refined sorghum flour (SF) used is limited in fiber and micronutrients because of bran removal during milling, and protein digestibility is poor due to kafrin crosslinking. In this research, the effects of Bambara groundnut (BG) (15%, 25%, 35%) and butternut (BU) powder (23%) blending on SF were investigated, using 100% SF as a control. The proximate, mineral, beta-carotene and folic acid compositions of the flour mix were determined. As the BG levels increased, the protein, fat, fiber, and ash contents increased significantly (p < 0.05), ranging between 8.62–14.19%, 2.36–3.38%, 1.37–3.04% and 0.87–2.19%, respectively. The iron, zinc, calcium and phosphorus contents in mg/100 g were 3.43–5.08, 2.96–3.74, 80.00–106.67 and 150.63–594.53, respectively. The beta-carotene (mg/100 g) and folic acid (μg/100 g) contents were < 0.01–0.63 and 0.75–1.42, respectively. The mineral, beta-carotene and folic acid contents of the flour mix varied significantly (p < 0.05) from the control. The pro-vitamin A beta-carotene content was improved in the blend flours with the addition of BU powder, whereas, in the control sample, it was not detected (<0.01 mg/100 g). With the 35% BG blend, increases of 37% protein, 45% crude fiber, 48% iron, 26% zinc, 133% calcium and 154% folic acid contents from the control were observed. The study showed food-to-food fortification of SF with BG flour and BU powder has the potential to combat malnutrition, and the public health challenges associated with deficiencies in bioactive fibers, proteins and micronutrients (pro-vitamin A carotenoids, folic acid and minerals)

An alternative food neophobia scale (FNS-A) to quantify responses to new foods

SUPPLEMENTARY TABLE 1. The 24 statements used in the study to describe responses of less (willing) and more (reluctant) neophobic individuals and the codes used to identify the statements (Study 1).SUPPLEMENTARY TABLE 2. Exploratory factor analyses, conducted in ten steps, to identify items that best fit in FNS-A (Study 1).An alternative Food Neophobia Scale (FNS-A) was developed in three studies to measure food neophobia (reluctance to eat and avoidance of trying new foods). In Study 1, the original food neophobia scale, FNS (Pliner, & Hobden, 1992), was first critically examined leading to modifications in five and omission of two statements. Furthermore, eight positive and eight negative statements were elicited and introduced along with eight original or modified FNS statements to 575 respondents in South Africa, Lesotho, and Botswana. Study 2 (n = 1010) was used to confirm the factorial structure of the scale, and Study 3 (n = 141) was used to test the reliability of FNS-A through test–retest data. The structure of the scale was analyzed using exploratory (Study 1 and 2) and confirmatory (Study 2) factor analysis, eventually leading to four positive and four negative statements regarding new foods, loaded on two factors labelled approach and avoidance. Test-retest reliability at a 2 weeks’ time interval as well as convergent and divergent validity measured against other scales was good (Study 3). In all three studies, predictive validity was evaluated against willingness to try or expected liking ratings of unfamiliar or novel food names or food concept descriptions. This evaluation showed satisfactory performance. FNS-A is a promising tool for the quantification of individual responses to unfamiliar or novel foods, but further studies in other populations and contexts are needed to confirm the applicability.Writing of the paper was supported by funding for a project: InnoFoodAfrica from the European Union’s Horizon 2020 research and innovation programme. Finnish University Partnership for International Development (UniPID) provided funding (project code 210000439011) that enabled final discussions among the authors and distribution of the questionnaire in South Africa, Lesotho and Botswana.Multi-item instrumenthj2023Consumer ScienceFood Scienc

Mashing with unmalted sorghum using a novel low temperature enzyme system: impacts of sorghum grain composition and microstructure

Brewing lager beers from unmalted sorghum traditionally requires the use of high temperature mashing and exogenous enzymes to ensure adequate starch conversion. Here, a novel low-temperature mashing system is compared to a more traditional mash in terms of the wort quality produced (laboratory scale) from five unmalted sorghums (2 brewing and 3 non-brewing varieties). The low temperature mash generated worts of comparable quality to those resulting from a traditional energy intensive mash protocol. Furthermore, its performance was less dependent on sorghum raw material quality, such that it may facilitate the use of what were previously considered non-brewing varieties. Whilst brewing sorghums were of lower protein content, protein per se did not correlate with mashing performance. Rather, it was the way in which protein was structured (particularly the strength of protein starch interactions) which most influenced brewing performance. RVA profile was the easiest way of identifying this characteristic as potentially problematic

Application of the deuterium-oxide dose-to-mother technique to determine the exclusivity of breastfeeding in women in Kanye, Botswana

Objective: The objective of the study was to determine breastfeeding exclusivity and impact on the nutritional status of mothers and infants.Design: This was an observational descriptive study.Setting: The setting was government clinics in Kanye, Botswana.Subjects: Women who gave birth to singleton healthy babies participated in the study.Method: Milk intake and breastfeeding exclusivity were determined by the deuterium-oxide dose-to-mother technique. Nutritional status was assessed using anthropometric measures (height and weight) in 56 mother-infant pairs at six weeks, and again at three and six months postpartum.Results: Mothers overestimated exclusive breastfeeding rates at all of the time points. However, according to the deuterium-oxide dose-tomother technique, at three months 61% of the mothers were exclusively breastfeeding, 13% were predominantly breastfeeding, and 27% were partially breastfeeding. At six months, none of the mothers were exclusively breastfeeding. The mean body mass index (BMI) and the percentage of body fat of the mothers in all of the groups were within the healthy range of 23.9 kg/m² and 28.3%, respectively, at six months. Mean infant weight was 6.1 ± 0.95 kg, 7.6 ± 1.28 kg and 8.4 ± 1.22 kg at three, six and nine months, respectively. Infant undernutrition based on weight for age was &lt; − 2 standard deviation. Malnutrition was 5.2% and 1.7% at six weeks and six months, respectively.Conclusion: Contrary to reported high rates of breastfeeding in Botswana, low rates of exclusive breastfeeding were observed with the deuterium oxide dose-to-mother technique. Therefore, this technique can be applied as a reliable method of validating mothers’ reports and their recall of exclusive breastfeeding practices. In future, the application of this method would be helpful to identify challenges in infant feeding practices, policies and programmes, all of which need further prioritisation within the Botswana context

Terminalia Prunioides pods herbal tea: Antioxidant activity, proximate, and metal content analysis

Growth in the demand for herbal teas has led to an increase in their research and commercial activities. In this study, the quantitative assessment of Motsiara (Terminalia prunioides) pods herbal tea was performed by determining antioxidant activity, total phenolic content, proximate and metal content. The studied extracts had a significant amount of phenolic content and antioxidant activity. The proximate analysis of ash, moisture, fat, crude fiber, protein, and carbohydrates gave results within the permissible limits for plant materials and teas. For metal analysis the following elements were at permissible values: K, Ca, Mg, Na, Mn, Ni, and Fe, while As, Cu, Cr, Co, Zn, and Pb were found at higher values. The preliminary data shows that T. prunioides pods are a potential source of natural antioxidants and minerals that can be useful in herbal tea formulations

Anti-atherogenic properties of Kgengwe (Citrullus lanatus) seed powder in low-density lipoprotein receptor knockout mice are mediated through beneficial alterations in inflammatory pathways

Kgengwe fruits are commonly consumed in sub-Saharan countries. Recent reports indicated low coronary artery disease rates in those regions. To investigate anti-atherogenic properties and potential mechanisms of action of Kgengwe seed powder (KSP), male low-density lipoprotein receptor knockout (LDL-r-KO) mice were fed with an atherogenic diet supplemented with (treated, n = 10) or without (controls, n = 10) 10% (w/w) KSP for 20 weeks. Proximate analysis revealed that KSP contained 38% fibre and 15% lipids. KSP supplementation was not associated with significant changes in body weight gain rate, food intake, and plasma lipid levels. However, the average atherosclerotic lesion size in the aortic roots in the KSP-treated group was 58% smaller than that in the control group (0.26 vs 0.11 mm2, p < 0.05). This strong anti-atherogenic effect was associated with significant increases in the average plasma levels of certain cytokines such as IL-10 (6 vs 13 pg/mL, p < 0.05), GM-CSF (0.1 vs 0.2 pg/mL, p < 0.05), and EPO (7 vs 16 pg/mL, p < 0.05) along with reductions in the average levels of plasma MCP-1 (19 vs 14 pg/mL, p < 0.05) and MIP-2 (28 vs 13 pg/mL, p < 0.05). Except for relatively high levels of saturated fatty acids, KSP possesses balanced nutrient compositions with strong anti-atherogenic properties, which may be mediated through alterations in inflammatory pathways. Additional studies warrant confirmation and mechanism(s) of action of such effects.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The Association of General and Central Obesity with Dietary Patterns and Socioeconomic Status in Adult Women in Botswana

Dietary patterns and their association with general and central obesity among adult women were studied using a cross-sectional survey with multistage cluster sampling in urban and rural areas nationwide in Botswana. The participants in the study were adult women (N = 1019), 18–75 years old. The dietary patterns were identified using principal component analysis, and their associations with the body mass index and the weight-for-height ratio were examined. Factor analysis with varimax rotation was used to identify six dietary patterns (fast foods, refined carbohydrates, vegetables and fruits, fish and nuts, Botswana traditional foods, and organ and red meat dietary pattern). Overall, 24.5% of the women were overweight (BMI 25.0–29.99 kg/m2) and 24.5% were obese (BMI > 30 kg/m2). A waist-to-height ratio greater than 0.5 was observed for 42.2% of the women. With adjustment for age and education, individuals in the highest tertile of the Botswana traditional food pattern had a significantly higher risk of general obesity (RR = 1.40, 95% CI: 1.07–1.84) and central obesity (RR = 1.20, 95% CI: 0.97–1.48). With respect to the fish and nut pattern, a significant association was observed with central obesity only (RR = 1.43, 95% CI: 1.18–1.72). The Botswana traditional food pattern, characterised by a high carbohydrate intake, was found to be associated with a high risk of obesity in this study. However, more research is required to assess other factors contributing to obesity in women so that appropriate intervention programs can be put in place to help control this epidemic