Optimization of the Formula and Process of Donut Enriched with Bagasse

By-products have traditionally been used as animal feed and are considered agricultural waste. However, they are rich in fiber and bioactive compounds, and efforts have been made to utilize them as functional ingredients and for the enrichment of food products. On the other hand, the intake of a sufficient amount of dietary fiber can regulate the flow of intestines, prevent and treat diabetes, cardiovascular and intestinal cancers. In this regard, in recent decades, there has been a tendency to seek new sources of dietary fiber and natural antioxidants, such as agricultural byproduct that were considered. In this regard, sugar cane bagasse, which has chemical compounds such as cellulose, hemicellulose, lignin, as well as phenolic compounds, waxes and minerals. Currently, bagasse used to production Cement (Tian et al., 2016), sand and grains (Sales et al., 2010), Chipboard (Garzon-Barrero et al., 2016), enzymes (Bocchini et al., 2005), single proteins (Rodriguez et al., 1992), vanillin (Mathew & Abraham, 2005), succinic acids (Chen et al., 2016), citric acid (Zhoghi et al., 2013), lactic acid (Laopaiboon et al., 2010). Donut is the only wheat industrial product that has a lot of attractive sensory features in spite of its high fat content. Therefore, one of the goals of the researchers in recent years has been finding solutions to improve its quality by reducing the absorption of oil or increasing the health components such as fiber. Therefore, this study was conducted to investigate the possibility of production of functional donuts that enriched with bagasse.

In this study, in order to optimize the formulation of donuts with two varieties of sugarcane bagasse fiber (0-25%), soybean soluble polysaccharide (0-2%) and frying time (2-5 minutes) on the physicochemical characteristics of donuts  and sensory properties by using mini-tab software  (version 16) and  central composite rotatable design (CCRD)  was investigated. The mean comparison was performed using Fisher test at 95% probability level. Bagasse were treated according to the method of Gao et al. (2013). Donuts were prepared according to the formulation by Nouri et al., 2017. Ingredients used in control donut formulation were consisted of 100 g of wheat flour (9  g/100g proteins, (Arde jonob Co., Khuzestan, Iran), 38 g of water, 9g of Shortening (Behshahr Industrial Co., Tehran, Iran), 13g of Egg, 13g of water for yeast, 6.3g of sugar, 6.3g of nonfat dried milk powder (Pegah Co., khozestan, Iran), 3g of active dried yeast (Nabmayeh, Khozestan, Iran), 1.6g of Vanilla extract (AbyazChimieEssence and Colour Co., Tehran, Iran), 1.6g of baking powder (Soheil Powder, Tehran, Iran), and 1.6g of Salt. The volume of the donuts was determined using the rapeseed displacement AACC method 10-05 (AACC, 2000). Moisture content of donuts crumb was measured using a Heraeus oven (model UT 5042, Germany) at 105 ºC for 3.5 h (Kim et al., 2015). The fat content of dried donuts was determined by Soxhlet extraction with petroleum ether for 5 h (Melito & Farkas, 2012). Firmness and springiness were measured in triplicate using a TA.XT2i Texture Analyzer (Stable Micro Systems, Goldalming, UK). The donuts were evaluated for over all acceptance of based on a five-point hedonic scale. The scale of values ranged from “dislike extremely” (score 1) to “like extremely” (score 5). And lightness was evaluated with Konica Minolta colorimeter.

The results showed that most of the proposed models in this study were proportional and meaningful from R2 and R2 (Adj). Also, the lack of fit these model were meaningless and their coefficient of variation was also appropriate. So, bagasse fiber increased moisture, hardness, cohesiveness and gumminess, fat, crust and crumb a, fiber and decreased specific volume, crust L. Increasing frying time increases hardness, cohesiveness, gumminess, and decreases crust L and moisture. Soybean soluble polysaccharide had no significant effect on these cases. According to the panelists, donuts containing bagasse fiber were harder and less chewable and had a darker color than the control sample. Response surface methodology described that donuts with optimum formulation of 9.09% bagasse fiber and 0.78% soybean soluble polysaccharide and the frying time of 2 minutes and 36 seconds would be the most desirable sample that has acceptable consumer characteristics. Investigating the optimal sample composition showed that iron and zinc mineral elements, fiber, fat, and total acceptance were higher than the control sample. However, no significant difference was observed in the control and optimum sample protein content. Also, with increasing durability, the moisture content of the product decreases. On the other hand, the specific volume of the control sample during the days of storage did not have a significant difference at 5% level. While the optimum sample volume in the days of shelf life has decreased. There was no significant difference between the control and optimum sample peroxidase in the first and third days, while on the fifth day, both were significantly decreased. The examination of texture characteristics suggests that the donut crumb of controlled and optimized was harder during the storage period, while the optimum sample was softer than the control sample.