ABSTRACT
This study was carried out to investigate the effect of different marinades on quality characteristics of chevon jerky. Chevon (Hindquarter muscle) was treated with marinades containing different levels of vinegar (0, 2.5% or 5% v/v) and papain (0, 0.004g/0.04gw/v). A 3×3 factorial design which composed of nine treatments with three replicates was used. Chevon was cut into 1.5cm x 1.5cm cubes and samples were marinated for 12h and dried in an oven for 10h at temperature of 65oC. Sensory and microbial characteristics, drying rate and rehydration ratio were determined. The samples for sensory analysis were vacuum packaged after drying and stored at room temperature. Due to the risk of mould growth on samples from treatments containing papain only (T2 and T3) after 15d of storage in a preliminary work, sensory evaluation was conducted on samples stored for 1d and 15d. Panelists were presented with randomly coded cooked samples and the tenderness, chewiness, juiciness; flavour and overall liking of the samples were evaluated using 8 point hedonic scale. The result of sensory properties showed that out of the nine treatments tested, papain (0.04g) was effective in tenderising the chevon jerky compared with all the other treatments. Samples were ranked as very tender to extremely tender while samples treated with vinegar (5%) was ranked as moderately tough to slightly tough. Samples from control (T1) obtained the highest acceptability score of 52.78% and was ranked as ―very like to extremely like‖ whereas papain 0.004g +vinegar 2.5% (T5) was the least scored 38.88% and was ranked as ―slightly like to moderately like‖. No significant (p > 0.05) differences were observed among treatments for chewiness, juiciness and flavour. However, juiciness improved with longer storage time at 15d. Samples evaluated at 1d were rated as ―extremely dry to very dry‖ (24.69%) but were ranked as ―very juicy to extremely juicy‖ (24.08%) at 15d. Samples for microbial test
were also vacuum packaged and stored at room temperature. Additionally, microbial quality analysis was conducted at 1d, 15d and 30d of storage and the effects of the nine treatments on the growth of four different microbes (total plate count, Staphylococcus aureus, E.coli, yeast and mould) during storage were investigated. As storage period increased from 15 to 30d total plate count increased from1.59 to 1.93log cfu/g, while E.coli count declined from 0.19 to 0.09log cfu/g. Additionally, Staphylococcus count decreased from 1.96 to 0.00log cfu/g and lastly as storage period progressed from 15d to 30d yeast and mould count declined from 1.17 to 0.30log cfu/g. Drying rate was determined by change in % moisture content per unit time during drying for 10h. The analysis showed that all the test samples recorded lower moisture content compared to that of the control (T1) after drying. Samples from vinegar (2.5%) recorded the least (1.71%) moisture content whereas the highest (3.61%) was observed in control (T1) samples. Rehydration studies were carried out on sample (1.5cm x 1.5cm) to distilled water ratio of 1:40 for 300min under ambient condition. As rehydration time progressed from time 0 to 300min there was an increase in weight among all test samples. Samples from control (T1) recorded the least moisture uptake of 9.83 whereas samples from vinegar 2.5% (T4) recorded the highest moisture uptake (19.94) after rehydration. Overall, the results of this study indicate that although overall likeness score favoured the control treatment, it is possible to improve meat toughness using papain to produce meat with acceptable sensory attribute than vinegar. Also, the drying process resulted in a jerky product with low moisture content which inhibited microbial growth; however, vinegar can be used in jerky production to add flavour to the product.
