Abstract:
Hal (Vateria copallifera) is an endemic plant in Sri Lanka and its bark contains
copelliferol A and B, two chemicals that have antiseptic properties. It has been
reported that Hal bark, containing polyphenolic compounds, can retard microbial
activity in various food products. Therefore, the objectives of the present study were
to determine, the best drying method for Hal bark, the best method and amount of
incorporation of Hal bark into foods, the sensory properties of Hal bark
incorporated sugar solutions and the effect of Hal bark on controlling yeast
fermentations in sugar solutions.
Hal barks were subjected to four drying methods such as drying at constant
humidity, cooling with dehumidifying, sun drying and shade drying. The best
drying method was selected by determining whether or not froth was formed within
30 min after adding Hal bark to the sugar solutions. Four sugar solutions 60% (w/v),
30% (w/v), 60% (w/v) with 3g Hal bark and 60% sugar solution boiled with 3g Hal
bark and kept overnight, after inoculation 1g of yeast were prepared and the effect
of Hal bark and yeast on reducing sugar content was determined. The effect of Hal
bark on glucose solution was studied using two glucose solutions added with 3g of
Hal bark and without Hal bark. To find out the best amount of Hal bark, different
amounts of Hal bark (1g, 2g, and 3g) and bark extract (1ml, 2ml, and 4ml) were
added to different strengths of sugar solutions such as 30% (w/v), 40% (w/v), and
50% (w/v). The yeast and mold count was determined using Sabouraud’s Dextrose
Agar. Sensory properties of Hal bark added sugar solutions were determined using a
5-point hedonic scale.
Cooling with dehumidifying appeared to the best drying method for Hal bark as it
showed the least froth formation in the sugar solution. The best sugar solution to
have maximum amount of antiseptic properties was 60%. Addition of Hal bark to
fermenting glucose solution decreased the reducing sugar content from 38.6g/100ml
to 32.2g/100ml. Hal bark can be incorporated into sugar solutions at a concentration
of 1% (w/v) whereas Hal bark extract can be added at a concentration of 2% (v/v)
without changing sensory properties. Addition of Hal bark to fermenting sugar
solution reduced the yeast population from 104 to 103 CFU/ml. Sugar solutions
incorporated with Hal bark and bark extract showed significantly higher (P<0.05)
sensory properties. The results suggest that Hal bark can be used as a natural
preservative in sugar related food products such as treacle, honey, candies etc.
