195 research outputs found
Digital imaging based classification and authentication of granular food products
No full textIn the food industry there are many types of product that are in the form of
particles, granules or grains. Consistent material size and quality within any
given sample is an important requirement that is well known in industry. In
addition it is possible that samples of material may be of unknown type or
have been subject to adulteration, thus making material authentication a real
requirement. The present work implements an advanced, but cost-effective,
digital imaging and image processing technique to characterize granular
foodstuffs either in real time process control or in an off-line, sample-based,
manner. The imaging approach not only provides cost-effective and rugged
hardware when compared with other approaches but also allows precise
characterization of individual grains of material. In this paper the imaging
system is briefly described and the parameters it measures are discussed.
Both cluster and discriminant analyses are performed to establish the
suitability of the measured parameters for authenticity study and a simple
fuzzy logic is implemented based on the findings. Tests are performed,
using rice as an example, to evaluate the performance of the system for
authenticity testing, and encouraging results are achieve
Empowerment and impact through informal or street food vending: a crop post-harvest project in Africa and South Asia
No full textEffect of roasting time and storage time on sensory attributes and consumer acceptability of peanut butters in southern Africa
No full textThis study explored how sensory attributes and consumer acceptability of peanut butters varied with differing roasting times (40 to 55 min) and storage times (up to 48 weeks) for shelf-life testing. Quantitative descriptive analysis generated sensory terms that were appropriate to the local situation. Increased roasting time was associated with the sensory attributes brown colour, roasted taste and burnt taste. Consumer acceptance varied among consumers with two preferred roasting times of either 40 min (67% of consumers) or 50 min (23% of consumers). This was related to distinct peanut flavour profiles. During the storage study of five selected butters consumer acceptability did not alter with storage period. Sensory testing, however, was more sensitive to product changes: sensory attributes that varied with storage were sticky texture, stale odour and sweetness
Study of sensory evaluation, consumer acceptability, affordability and market price of rice
No full textThe purpose of the study was to evaluate consumer acceptance, affordability and market value of a
prototype parboiled rice (PPR) in relation to three local samples and a high-value imported one. While descriptive
sensory evaluation and central location testing are used to evaluate consumer acceptability, this study suggests
that affordability and market price of rice can also be assessed. The PPR was acceptable and the suggested
market price was influenced by both affordability and acceptability. Acceptance scores suggested a potential
higher price; consumers discounted the prototype rice and the extent depended on affordability. The concept of
consumer acceptability and affordability varied widely among consumers and this was related to the market price,
demographics and attitudes towards rice. Sensory attributes associated with quality were positively related with
price but negatively with affordability. Acceptability was related to rice consumption and purchasing behaviour,
whereas affordability was associated with income, gender and quality perception. Low affordability groups knew
the least about the benefits of rice. The implications are discussed
International Editorial Advisory Board
No full textProfessor Sandro Scandolo, ItalyProfessor Alessandro Laio, ItalyProfessor Joel Koech, KenyaProfessor Jerome Nriagu, USADr. Arch. Barnabas Nawangwe, UgandaDr. Tomlins Keith, UKDr. Olaniran Fasina, USADr. (Mrs.) Prajeab Jammne, IndiaMr. V. Prakash, IndiaSubscription
Consumer acceptance of quality protein maize (QPM) in East Africa
No full textBACKGROUND: Undernutrition in sub-Saharan Africa remains problematic, and quality protein maize (QPM) can benefit populations whose diets are heavily based on maize and who are consequently at risk for inadequate intakes of quality protein. However, changes in the chemical composition of QPM may affect its sensory characteristics and, hence, acceptance. Acceptance tests were therefore conducted to evaluate QPM varieties in three East African countries using central location tests with one or two varieties in each country, using the most popular preparations: ugali (Tanzania), githeri (Kenya) and injera (Ethiopia). In total, 281 urban and rural consumers of both sexes and varying levels of education evaluated the products on standard sensory criteria: appearance, aroma, texture, taste and overall, using a Likert scale.
RESULTS: The results show that African consumers can differentiate QPM products from their conventional counterparts, indicating that the QPM trait results in distinguishable sensory changes. Analysis by ordinal mixed regression models showed that consumers found QPM acceptable and even preferable to conventional maize.
CONCLUSION: The sensory characteristics of QPM are therefore no impediment to its adoption; on the contrary, when coupled with good agronomic performance, they may help its utilization, leading to a positive impact in nutritionally vulnerable populations
International Editorial Advisory Board
No full textª¤? Professor Sandro Scandolo, Italyª¤? ª¤?Professor Alessandro Laio, Italyª¤? ª¤?Professor Joel Koech, Kenyaª¤? ª¤?Professor Jerome Nriagu, USAª¤? ª¤?Dr. Arch. Barnabas Nawangwe, Ugandaª¤? ª¤?Dr. Tomlins Keith, UKª¤? ª¤? Dr. Olaniran Fasina, USAª¤? Dr. (Mrs.) Prajeab Jammne, Indiaª¤? ª¤?Mr. V. Prakash, Indiaª¤?ª¤
Effect of pretreatments for retaining total carotenoids in dried and stored orange-fleshed-sweet potato chips
No full textVarious dipping pretreatments have been investigated for orange-fleshed sweet potato (OFSP) to retain carotenoids after drying and subsequent storage. Effects of blanching, sodium metabisulfite (0.5 or 1%), acids (ascorbic acid [1%] or citric acid [0.5%]) or salt (1%), either singly or as mixtures, were tested on dried OFSP chips that were stored for up to 6 months in ambient conditions. Overall, there was a positive effect of dipping on total carotenoid content after drying compared with control (P < 0.05). A slight improvement in carotenoid content was observed during the first month of storage with ascorbic acid, sodium metabisulfite, and mixtures of sodium metabisulfite and citric acid, or ascorbic acid and salt pretreatments, but these higher levels were not maintained over longer storage periods (4–6 months). The general lack of improvement was believed to result from the leaching and degradation of the chemicals during storage
Sensory properties and consumer acceptance of novel hibiscus (hibiscus sabdariffa) beverages
No full textAs bebidas à base de extratos de hibisco são ricas em ácidos orgânicos, compostos fenólicos e polissacáridos, substâncias com potenciais benefícios para a saúde, sendo tradicionalmente consumidas na Africa Ocidental, na Ásia e na parte sul da América do Norte. A sua divulgação na Europa e dos Estados Unidos tem sido lenta e dirigida sobretudo a nichos de mercado, no entanto, o crescente interesse dos consumidores europeus e norte-americanos em bebidas com ingredientes únicos ou exóticos, com potenciais benefícios para a saúde, criaram recentemente novas oportunidades de mercado para bebidas de hibisco de alta qualidade.
Entre 2010 e 2015, o projeto Europeu African Food Tradition rEvisited by Research (AFTER) investigou a produção, a comercialização e o consumo de bebidas de hibisco (Hibiscus sabdariffa var. sabdariffa ruber) no Senegal e na Europa, com o objetivo de otimizar a sua produção industrial, minimizando a degradação dos compostos fitoquímicos. Pouco se sabia sobre o perfil sensorial destes produtos, na sua forma tradicional ou melhorada e sobre como as mesmas eram avaliadas pelos consumidores, fatores essenciais para o sucesso destes produtos em particular fora dos seus mercados tradicionais. Esta dissertação teve como objetivo avaliar o impacto da otimização dos processos de produção industrial das bebidas de hibisco levadas a cabo pelo projeto AFTER (1) nas propriedades físico-químicas dos produtos resultantes com impacto na qualidade sensorial; (2) no seu perfil sensorial; (3) na perceção e aceitação por parte dos consumidores em mercados tradicionais (Senegal) e potenciais (França, Portugal e Reino Unido).
O uso de cálices de hibisco secos à sombra e triturados das cultivares Vimto e Koor (50:50) e de condições moderadas de tempo e temperatura de extração e pasteurização, deu origem a novas bebidas com uma cor mais intensa e mais vermelha, maior concentração em antocianas monoméricas e polifenois e consequentemente maior capacidade antioxidante do que as bebidas convencionais, maior equilíbrio entre a concentração de açúcares e de ácidos e maior intensidade aromática. O estudo efetuado com consumidores no Senegal (N=150), mostrou que as novas bebidas foram positivamente avaliadas e melhor apreciadas que bebidas convencionais, sem que a perceção do caracter tradicional tenha sido alterada. Três segmentos de consumidores com distintos padrões de aceitação das bebidas foram identificados. A avaliação hedónica foi influenciada por preferências pessoais relativamente à cor, aroma e equilíbrio doçura-acidez, por características sociodemográficas e hábitos de consumo.
Vinte e duas bebidas de hibisco foram avaliadas por painéis de provadores no Senegal e em Portugal. Léxicos em Português, Inglês e Francês contendo 21 descritores definidos, e referenciados foram desenvolvidos. As características distintivas das bebidas de hibisco eram a cor vermelha, o aroma floral (hibisco) e frutado (aronia/arando, ginja e framboesa) e o sabor predominantemente ácido (infusões de hibisco e bebidas preparadas a partir de concentrados) ou doce (bebidas preparadas a partir de xaropes). Eram ainda percetíveis aromas de chá preto, passa de uva, mel e feno, assim como sabor amargo e adstringência. O vocabulário usado por profissionais não-treinados (N=30) e por consumidores foi estudado usando entrevistas semiestruturadas (N=75) e questões Check-all-that-apply (N=490) no Senegal, em França, Portugal e Reino Unido. Léxicos gráficos contendo 27 atributos sensoriais e 15 termos gerais foram desenvolvidos. Diferenças com origem na cultura e familiaridade com o produto foram observadas. A comparação dos perfis sensoriais obtidos com provadores treinados e consumidores permitiu uma melhor compreensão da linguagem destes últimos.
Estudos com consumidores em França, Portugal e Reino Unido (N=403) mostraram padrões similares de aceitação e perceção pelos consumidores. Diferenças importantes foram observadas relativamente ao Senegal. Na generalidade, os consumidores na Europa, gostaram menos das bebidas do que no Senegal, embora avaliações hedónicas médias positivas tenham sido observadas para todas as bebidas. No Senegal os consumidores avaliaram mais favoravelmente uma maior intensidade de cor e maior doçura e de forma mais depreciativa menor acidez. Na Europa e caracter floral e frutado das bebidas constituíram importantes fatores de aceitação das mesmas. Segmentos de consumidores foram identificados. A aceitação e perceção foram influenciadas pela familiaridade com o produto e com produtos com características de algum modo similares na Europa (caso dos sumos de frutos vermelhos); por características sociodemográficas; e por preferências individuais inatas ou culturalmente adquiridas. Foram observadas diferenças entre segmentos de consumidores na Europa relativamente ao perfil sensorial de uma bebida ideal, mas não no Senegal.Hibiscus beverages are rich in organic acids, phenolic compounds and polysaccharides, which have been demonstrated to be linked to important health benefits. They are traditionally consumed in West African countries, in Asia and in the Southern part of the North American continent. In Europe and United States of America, hibiscus beverages have slowly penetrated niche markets. Due to the rising number of health conscious consumers, along with the growing interest of North Americans and Europeans in beverages made from unique or exotic ingredients, new mainstream market opportunities for high quality hibiscus beverages have been recently created.
Between 2010 and 2015, the African Food Tradition rEvisited by Research (AFTER) project, investigated the production, trading and consumption of hibiscus beverages made from dried hibiscus (Hibiscus sabdariffa var. sabdariffa ruber) calyx extracts in Senegal and Europe. Key improvements were proposed to increase production process efficiency and minimize degradation of phytochemical compounds. The aims of this thesis encompassed the evaluation of the impact of the reengineering processes held under AFTER project scope (1) in the main chemical-sensory properties of hibiscus beverages; (2) on their sensory profile; (3) on consumer acceptance in traditional markets (Senegal) and potential markets (France, Portugal and United Kingdom).
The selection of a blend of shade dried ground hibiscus calyces (Vimto:Koor cultivars 50:50) and the use of mild water extraction and pasteurization conditions, led to the production of beverages with a more intense redder colour, higher monomeric anthocyanin, total phenolic content and higher antioxidant capacity than their conventional counterparts. Colour evaluation by trained panelists was mainly linked to colour density and to anthocyanin/polyphenol content, while flavour assessments were associated to titratable acidity and sugar-to-acid ratio. New beverages presented also a more intense aroma than conventional ones. Results of hedonic assessments held in Senegal (N=150), indicated that all improved beverages were liked by roughly three-quarters of consumers and were better accepted than a traditional one (baseline comparison). Three clusters of consumers with distinct overall liking patterns were identified. Acceptance was driven personal preferences regarding colour intensity, aromatic character, balance between sweetness and acidity but also by gender, age frequency of consumption and education level. Importantly, new beverages were still perceived by consumers as traditional products.
Given the scarcity of information about hibiscus beverages sensory profile, sensory lexicons were developed in French, Portuguese and English. Twenty-two samples, including freshly prepared and ready-to-drink infusions, syrups, concentrates and an instant tea, were evaluated by trained panelists, resulting in 21 defined and referenced descriptors, subsequently assembled in a sensory wheel. A distinctive red colour, a floral (hibiscus) and fruity aroma (aronia/cranberry, sour cherry and raspberry) and a predominant acid (in case of infusions and beverages prepared from concentrates) or sweet taste (for beverages prepared from syrups) were the main sensory attributes. Also moderate or low intensities of black tea, honey, raisin and hay odours and of bitter taste and astringency were perceived in all products. The vocabulary used by untrained panelists was also investigated in Europe and Senegal through professional meetings (N=30), consumer focus groups (N=75) and check-all-that-apply questions (N=490), resulting in graphical lexicons with 27 sensory and 15 overall impression terms. Training, food culture and product familiarity influenced results. Trained panelists used precise terms to describe the aromatic profile of hibiscus beverages (e.g., reminiscent of dried hibiscus flowers, with berry, raisin, hay and sweet notes), whereas untrained ones were more prolific in general expressions (e.g., strong in hibiscus in Senegal; floral and fruity in Europe).
Consumer studies in France, Portugal, United Kingdom (N=403), showed similar patterns of acceptance and perception for hibiscus beverages in European countries. Positive mean overall liking ratings were observed for all beverages. Major differences were observed relatively to Senegal where consumers favored higher intensities of red colour and sweetness. In Europe fruity and floral character constituted important drivers of liking. Consumer segments were identified. Perception and acceptance was influenced by consumers’ sociodemographic characteristics and by innate and culturally acquired preferences. Besides exposure to product category, also exposure and liking of familiar products, with somewhat similar characteristics to hibiscus beverages (like red fruit beverages), was shown to influence liking in Europe. Differences across consumer segments in the profile of an ideal beverage were observed in Europe but not in Senegal
Investigating carotenoid loss after drying and storage of orange-fleshed sweet potato
No full textBiofortified orange-fleshed sweetpotato (OFSP) is being promoted to tackle vitamin A deficiency, a serious public health problem affecting children and pregnant/lactating women in sub-Saharan Africa. The aim of the study was to quantify and understand the factors influencing carotenoid losses in dried OFSP. Losses were determined in chips after drying and storage. A preliminary study demonstrated that carotenoid levels were not significantly different following either solar or sun drying. Carotenoid loss after drying was generally correlated with high initial moisture content and high carotenoid content in fresh sweetpotato roots. Losses of pro-vitamin A were less than 35% in all cases. Flour made from OFSP could therefore be a significant source of provitamin A. In contrast, storage of chips at room temperature in Uganda and Mozambique for four months resulted in high losses of pro-vitamin A (ca. 70-80% loss from the initial dried product). Low-cost pre-treatments, such as blanching, antioxidants and salting, did not reduce carotenoid losses during storage. Enzymatic catabolism of b-carotene in dried OFSP was considered unlikely because of low peroxidase activities at low water activities and the loss of peroxidase activity during storage. To understand further the factors causing the losses, dried sweet potato chips were stored under controlled conditions of temperature (10; 20; 30; or 40ºC), water activity (0.13; 0.30; 0.51; 0.76) or oxygen (0 [under nitrogen]; 2.5; 10 or 21% [air]). Oxygen was the main cause of degradation followed by temperature. An Arrhenius kinetic model was used to show that carotenoid breakdown followed first order kinetics with an activation energy of 68.3kJ.mol-1 that was in accordance with the literature. Experimental observations fitted well with data predicted by the kinetic model. The formation of the volatile compounds,b-ionone; 5,6-epoxy-b-ionone; dihydroactinidiolide; b-cyclocitral that were clearly related to the degradation of b-carotene, helped further understand breakdown patterns of b-carotene
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