1SEAFAST Center and 2Dept. of Food Science and Technology, Bogor Agricultural University
ABSTRACT
Rice-Based Emergency Canned Food (RB-ECF) has been made from rice and meat (chicken) as a main ingredient; which is produced to fulfill the required daily energy level (2100 kcal) and consumed directly in emergency condition. The product was packed in 307 x 113 silver enamel can and canned in retort at 250°F (Tr) with CUT = 21 minutes. The product's weight was 200 gram per can with the total energy value was 639.42 kcal. The total energy value was got from fat (49.63%), protein (11.26%), and carbohydrate (39.11%).
Rice with different amylose content (19.50% –Cisadane, 23.88% -IR 64 and 28.24% -IR 42) has been used to make RB-ECF. Thermal processing was carried out by different time–temperature schedules to achieve 15 and 20 minutes sterilized value (Fo). Objective analysis of the products showed that amylose content and Fo value affected the color and texture of the products.
I. INTRODUCTION
Emergency food product is a processed food for emergency situations, which can be consumed directly and meet the daily nutritional needs. The main characteristics is good palatibility, safe to consume, easy to distribute, and contain sufficient nutrients daily needs. Ideally, contribution of calories from protein, fat and carbohydrate respectively is 10-15%, 35-45% and 40-50% (Zoumas et al, 2002).
Rice (Oryza sativa) is consumed mainly in the cooked form. Because it is the staple food for most Indonesian people, the development of rice-based emergency canned food (RB-ECF) needs to be done. Starch is the major component of rice and consequently play an important role in food product quality. Functional properties of starch have considerable effect on the quality of starch-based product (Bhattacharyya et al, 2004; Kaur et al, 2005).
Length of time process that needed to achieve a certain sterilized value at retort commercial sterilization, significantly change the color and texture of food canned. Retort sterilization will normally disrupt starch structure which leads to a soft, mushy texture not well-regarded by consumers. Past research showed that apparent amylose content was the best overall indicator for predicting canning stability (Patindol et al, 2007).
The objective of this study was to observe the effect of different time–temperature schedules to achieve sterilized value (Fo) and amylose content of rice on the color and texture of the RB-ECF.
II. MATERIAL AND METHODS
Rice with different amylose content (Cisadane, IR 64 and IR 42) and other ingredients were procured from Pasar Bogor. The starch and amylose content of rice was determined by DNS method and iodometry method respectively (both as described by Apriyantono et al, 1989); and amylopectin content obtained as the difference of starch content with amylose content (Table 1).
RB-ECF was prepared as shown in Figure 1, used rice and meat (chicken) as a main ingredient. Product was canned in silver enamel can, 307 x 113 in size. Weight of product was 200 gram per can with the total energy value was 639.42 kcal. Distribution energy from fat, protein and carbohydrate were 49.63, 11.26 and 39.11%. Thermal processing was carried out by different time–temperature schedules at 250oF to achieve 15 and 20 minutes sterilized value (Fo) was shown in Table 2.
Color analysis of product was made using chromameter (Minolta CR-200) for L value, a value and b value. Texture profile analysis was performed at room temperature by using TA-XT2 texture analyzer. Hardness, springiness, cohesiveness, gumminess, chewiness and adhesiveness were determined.
III. RESULTS AND DISCUSSION
1. Color Properties
RB-ECF color was significantly affected by amylose content of rice and processing time (Figure 2-3). Amylose content affected the brightness value (L value) and a-value, but they insignificantly affected b-value of RB-ECF. L-value of product increased with increasing amylose content, and blueness (-a value) were vice versa. According to Haryadi (2006), rice with high amylose tend to absorb more water and expand bigger when they were cooked and made their color becomes brighter.
Processing time affected the color of product. This result is in accord with Bhattacharya (1996), who found that pressure and steaming time had marked effects on product's Hunter color. The decrease of the brightness was more pronounced at longer processing time. Severe cooking had less effect on yellowness (b value) than on blueness (-a value). The color change has been hypothesized to be caused mainly by non enzymic browning of the Maillard reactions (Lamberts et al, 2006).
Hardness and stickiness is the most important physical properties of RB-ECF among all the physical properties, which makes significant influences in increasing consumer acceptability. Amylose content strongly influences hardness and stickiness (adhesiveness) of rice product. Figure 4 showed the hardness and gumminess of product increased as amylose content increased, were adhesiveness vice versa. Rice with a high amylose content tends to cook firm and dry, whereas rice with a intermediate amylose content tends to be softer and stickier and rice with a low amylose content is quite soft and sticky. This result agree with Bhattacharya et al (1999) that concluded that apparent amylose content was highly correlated with rice noodle hardness, gumminess, and chewiness. This result is also in line with Ong and Blanshard (2002) that found that hard cooking rice tended to have a higher amylose content (or amylose:amylopectin ratio) and more longer chain amylopectin than soft cooking rice, which feature is thought to encourage more extensive intra and/or inter molecular interactions with other components in rice grain, such as protein, lipid and non-starch polysaccharides and results in a firmer texture.
Slightly decreasing of hardness and increasing of stickiness were found when processing time was increased. It was probably due to deformation of the grain and exposed endosperm after grain splitting sharply changed hardness and stickiness values. Increasing time sterilisation also induced high gelatinization, wich resulted in a softer and stickier texture in the product.
Springiness value of product varied from 0.901 until 1.006 mm, where amylose content made a small variation in springiness. This results were agreement with a previous report by Cheng et al (2005). Interaction of amylose content and processing time affected springiness value differently. At the Fo was 15 minutes, the springiness of product increased as amylose content increased. The springiness value decreased with increasing amylose content at the longer time processing (Fo = 20 minutes). The different of amylopectin structures may explain why rices can have different springiness properties.
Amylose content had positive impact strongly influences hardness and stickiness of rice product. Figure 4 showed the hardness and gumminess of product increased as amylose content increased. Chewiness refers to number of chews required to masticate product before it was suitable for swallowing or the amount of work required to chew the sample for sensory evaluation. It was observed that amylose content had main effects on chewiness. Chewiness increased with the increase in amylose content, but not affected by processing time (Figure 4).
IV.CONCLUSION
The results demonstrate that time schedulling (processing time) of thermal processed and amylose content of rice distinctly affected color and texture of RB-ECF. These treatment affected the brightness value (L value) and a-value, but they insignificantly affected b-value of product. At product texture, amylose content strongly influences hardness, gummines, chewiness and stickiness (adhesiveness) whereas time schedulling affected hardness, gumminess and adhesiveness values.
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