การพัฒนาผลิตภัณฑ์ผลไม้ความชื้นสูงโดยใช้เทคโนโลยีเฮอร์เดิล / เกตินันท์ กิตติพงศ์พิทยา = Development of high moisture fruit product by hurdle technology / Ketinun Kittipongpittaya
High moisture fruit products are the fresh-like fruit products with high a[subscript w] (> 0.93), which is favorable to the microorganisms. The objective of this research was to develop high moisture fruit product by hurdle technology which is the technique that combines factors such as slight reduction of a[subscript w], pH , addition of spice essential oil and low heat treatment to achieve the microbiological stability of product. Guavas of similar maturity and weight (250-280 g) were diced approximately to 1cm* 2cm *1cm size. Appropriate condition for drying diced guava was studied and found that vacuum drying at 70 ํC for 5 hours gave dried guavas with 34.02 % moisture content and a rehydration ratio of 3. They were put into pineapple puree, papaya puree and passion fruit juice at ratio of dried guava and puree 1:8 (w/w) to get new product with attractive flavor and to reduce a[subscript w] of puree, heated to 80 ํC for 10 min and stored under refrigeration overnight. Sensory evaluation was performed and it was found that dried guava in pineapple puree and in papaya puree were accepted. The ratio of dried guava and puree was then chosen by sensory test and found to be 1:8 (w/w). Essential oil of ginger, cinnamon, clove and nutmeg was added to the product and the sensory test was carried out to select the appropriate one. The product with ginger oil at 2.0 microletre/100 g puree had the highest score for color and flavor. The effect of combined treatment between mild heat treatment was determined with adding ginger oil of 2.0 microletre/100 g puree. It was seen that the ginger oil had no effect on microbial growth significantly (p>0.05) and the temperature and time 80 ํC 10 min for dried guava in pineapple puree and 80 ํC 15 minutes for dried guava in papaya puree was found sufficient to inhibit microbial growth with acceptable sensory value. The effect of lowering a[subscript w] and pH, using fresh ginger and mild heat treatment was studied and found that these hurdles except using fresh ginger had the effect on stability of the product. Storage test of the product was conducted to investigate alterations in physical, sensory and microbilogical properties. This was done byproducing the product under selected condition, adding ginger oil of 2.0 microletre/100 g puree, packing 450 g of product in the glass bottle and storing under room temperature (25-27 ํC) and refrigeration (4-5 ํC) for three months. It was evident that firmness of dried guava both in pineapple and papaya puree decreased as storage time increased. The yellowness of pineapple puree trended to increase while the redness of papaya puree reduce during the storage time. However, the product could be kept for at least 1 month at room temperature and at least 3 months in the refrigerator. This high moisture fruit product should be another choice for consumers. It gives pleasant color, flavor and texture of fruits especially when kept in the refrigerator as a dessert.
