Doctoral Degrees (Microbial, Biochemical and Food Biotechnology)

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Browsing Doctoral Degrees (Microbial, Biochemical and Food Biotechnology) by Subject "Alfalfa"

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    The chemical, microbial and sensory evaluation of lucerne (Medicago sativa L.) for human consumption and acceptability
    (University of the Free State, 2014-06) Mielmann, Annchen; Hugo, C. J.; Bothma, C.
    English: Lucerne (Medicago sativa L.) has not recently been investigated as an alternative protein source for human consumption in SA. The chemical (degrees Brix, macro- and micro-minerals, protein, AA, dry matter, moisture, ash, fat, fibre, carbohydrates and energy content) composition, microbial content, and shelf-life of three lucerne cultivars, ‘SA Standard’ (‘SAS’), ‘WL525’ and ‘WL711’, were investigated. It was compared to SB (Beta vulgaris var. cicla L.), to identify the lucerne cultivar to use for future research purposes. The Brix content of the lucerne cultivars was significantly (p<0.01) higher than SB. Raw lucerne cultivars had significantly (p<0.01; p<0.001) higher Ca and S contents than raw SB. The K, S and Mn content for the raw lucerne cultivars were significantly (p<0.001) higher than the cooked cultivars. The protein content of the raw lucerne cultivars were significantly (p<0.001) higher than the raw SB. Cooked ‘SAS’ and ‘WL525’ had significantly (p<0.001) higher protein contents than cooked SB. Both raw and cooked ‘SAS’ had a significantly (p<0.001) higher carbohydrate and energy contents than both raw and cooked ‘WL525’, ‘WL711’ and SB. The lucerne cultivars contained higher values of essential and non-essential AA than SB. The total bacterial count, coliform count, lactic acid bacteria count and mould count conformed to standards, while cooking significantly (p<0.001) reduced the bacterial load. The shelf-life of cooked lucerne and SB samples were of satisfactory microbiological quality until day seven. The sensory descriptive attributes of the three lucerne cultivars were determined, by using GDA, and consumers’ acceptance (degree of liking for aroma, taste, mouthfeel and overall acceptability). ‘SA Standard stew’ showed the lowest value, of the lucerne samples, for fibrous appearance, chewy and fibrous mouthfeel, bitter taste, and bitter and metallic aftertaste. Principal component analysis showed that, three stew samples (SB, ‘SAS’ and ‘WL525’) and plain SB displayed ‘positive’ attributes, such as soft and wet appearance, spinach beet aroma and salty taste. ‘WL711 stew’ and three plain samples (‘SAS’, ‘WL525’ and ‘WL711’) were associated with ‘negative’ descriptors, namely grassy aroma, fibrous and chewy texture, fibrous appearance, bitter taste, and bitter and metallic aftertaste. ‘SA Standard stew’ was the most preferred lucerne cultivar, as it’s values for degree of liking for aroma, mouthfeel, taste and overall acceptability were numerically higher than ‘WL525’ and ‘WL711’. External preference mapping indicated that three consumer clusters, with different lucerne preferences, were obtained by AHC. ‘SA Standard stew’ was the lucerne sample preferred by all the consumers, except those with some primary education and a yearly income of R501 000 – R750 000 per year, who indicated only a high acceptance for this sample. While 63.1% of the respondents knew what lucerne was, 77% was unfamiliar with the term ‘alfalfa’ and 90.3% never consumed lucerne before. Younger respondents of the white population group, with a grade 12 or higher education, were significantly (p<0.001) more knowledgeable about lucerne. The predictors, sensory qualities and synonyms, contributed significantly (p<0.001) to consumers’ attitudes towards lucerne. While respondents believed that ‘health general’ (40.1%) was the most important advantage of eating lucerne, ‘sensory properties’ (35.4%) and ‘vegetables spinach’ (24.5%) were regarded as the most important disadvantage and association, respectively. The differences in lucerne knowledge of respondents from different demographic backgrounds indicated a need to inform SA consumers, on the benefits of consuming lucerne. Based on these findings, lucerne could be implemented as an alternative vegetable protein and therefore, cultivar ‘SAS’ was proposed for future studies and product development.