Article

Development of Fermented Taro as a Food Preservative Ingredient in Intermediate Moisture Products

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Abstract

This study focuses on the functionality of fermented taro as an antibacterial ingredient for intermediate moisture (IM) products being developed by the military. The taro is cooked and then inoculated with a food-grade bacterium, Lactococcus lactis ssp. lactis, which produces a bacteriocin, nisin, forming a fermented taro product. The fermented taro has antibacterial activity against various bacteria and is freeze-dried for eventual incorporation as a food preservative ingredient in an IM product. L. lactis yielded nisin concentrations in a range of 15,000-19,000 AU/g of taro. Challenge studies were conducted in which the fermented taro was incorporated into an IM product, the burrito sandwich. The challenge organisms consisted of three strains of Staphylococcus aureus. The burrito samples with 600 AU/g of fermented taro showed no increase in bacterial counts after 7 days. However, after 14 days the bacterial counts increased to 3 X 107 CFU/g. The burrito samples treated with 1200 AG/u of fermented taro showed no increase in growth from the original inoculum (2 X 105 CFU/g) during the challenge study. The last sampling time was at 56 days with a slight decrease in the S. aureus counts. It appears that fermented taro can be a good food preservation ingredient in IM products, though further studies will have to be done to optimize product.

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... A reduction in the amount of enteropathogenic bacteria of the Enterobacteriaceae family may be due to events that occur during the fermentation process as follows: (i) competition for receptor sites of lactobacilli ingested from fermented feed (Mulder et al. 1997), (ii) lactic acids and VFAs created by LAB and fermented feed (Prohaszka et al. 1990), (iii) antimicrobial compounds produced by LAB (Apella et al. 1992; Olsen et al. 1995), (iv) low pH (Burnell et al. 1988; Ravindran and Kornegay 1993), and (v) a combination of these factors. In addition, the activity of bacteriocin in fermented taro could be another factor that reduces pathogenic bacteria (Muller et al. 2005). Therefore, the fermentation process of SCRS in our experiment may have induced the events mentioned above and may therefore be responsible for the changes in the cecal bacteria profi le of the pigs. ...
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... To increase the pH of the sandwich, sodium bicarbonate was added to the formulation. This change was also required in a previous study using nisin as a preservative in a burrito IM product (Muller et al., 2003(Muller et al., , 2005. The BCS included only two of the BIs: purasal and nisin. ...
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Military intermediate moisture (IM) sandwiches have a shelf life requirement of two years at 80 degrees F. The stability of IM sandwiches is maintained using Hurdle technology, which typically provides a pH below 5.5 and a water activity below 0.89. These levels are effective for microbial stability; however, they can have an effect on the sensory quality of the product and can limit the development of new products. This report describes a series of challenge studies to raise both levels. Two IM products, the Italian pocket sandwich (IPS) and the bacon cheddar sandwich (BCS) were reformulated to a pH above 6 and a water activity above 0.9. Various bioactive ingredients (BIs) were then added to the reformulations (as an additional hurdle), in the form of Purasal(R)P (lactate/diacetate), epsilon-polylysine, or Nisaplin (R)(nisin), to provide microbial stability. The studies were conducted on the reformulated products with five different strains of Staphylococcus. aureus, which would be the most likely microbial contaminant in these products. The studies were carried out for 180 days at 25 degrees C. For the IPS the three BIs were incorporated into both the bread and the filling. It was determined that 4% purasal, 2.5% epsilon-polylysine, and 1.2% nisin were effective in inhibiting the growth of S. aureus. For the BCS only purasal and nisin were incorporated. They were added in the same concentrations as in the IPS, but were incorporated only in the bread. Results were similar; however, there was less S. aureus growth in the BCS control than in the IPS control. Though all three ingredients inhibited the growth of S. aureus, nisin appeared to be the most effective based on its ability not only to inhibit growth, but also to reduce the original bacterial population. It also had less effect on the sensory properties.
Article
Tubers are important sources of carbohydrates as an energy source and are used as staple foods in tropical and subtropical countries. They are generally processed into various forms before consumption. Processing makes them digestible and palatable, extends the shelf life and reduces post-harvest losses. Taro (Colocasia esculenta) is a tropical tuber crop largely produced for its underground corms contain 70–80 % starch and the corms of Colocasia antiquorum contain anthocyanins such as cyanidin-3-glucoside, pelargonidin-3-glucoside and cyanidin-3-chemnoside which were reported to have antioxidative and anti-inflammatory properties. Taro consumption has been affected by the presence of acridity factors, which cause sharp irritation and burning sensation in the throat and mouth on ingestion. Taro is rich in gums (mucilage) and small sizes of starch granules makes it a highly digestible which is used for the preparation of various foods. The present paper deals with reviewing the nutritional, antinutritional and utilization of Taro into the various food products.
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