Applications of sand roasting and baking in the preparation of traditional Indian snacks: nutritional and antioxidant status

Background In India, the sand roasting technique is widely used by street food vendors, villagers and cottage industries for making various value-added food products from different cereals, millets and legumes. The traditionally produced sand-roasted products are commonly utilized as ready to eat snacks or for the preparation of various other snacks. Results During the high-temperature short-time treatment of sand roasting, the produced products are bestowed with characteristics such as higher puffing, crispiness, volume, and improved color, aroma, flavor and texture. In terms of nutrition, the roasting process enhances the carbohydrate and protein digestibility, β-glucan extractability, levels of dietary fiber, minerals, and antioxidants and reduces the inherent antinutrients levels in cereals and legumes. In addition, the complete destruction of seed microflora enhances the shelf life and thus consumer acceptance. The sand-roasted products act as prebiotic dietary fiber and serves as an alternative to polished grains for the consumers. Thus, the simplest, inexpensive, traditional sand roasting method of dry heat application is used for making precooked ready to eat weaning foods and preparation of cost-effective dietary pediatric and geriatric formulations. The technique is also employed for roasting various beans, fryums, nut, and pulse decortication and as a pretreatment process for tamarind kernel powder production, while the sand baking method is widely used for baking cakes, vegetables, meat, fish, eggs and starchy tubers. Conclusions The techniques of sand roasting and baking are gaining importance as cheap, effective, oil-free, healthier ways of cooking. However, further studies are needed on micronutrient availability and functional food development for community nutritional disorders. Also, the residual silica levels and difficult working environment mandates the development of energy-efficient and high-output-orientated technologies such as continuous, microwave, and fluidized bed roasters.

Pulsed Infrared Roasting of Groundnuts and its Quality

The application of high intensity, pulsed infrared radiation for roasting of groundnuts is attempted and the product quality is compared with that of the conventionally roasted samples. Product qualities such as lightness (color), compressive strength (texture) and free fatty acid content are analyzed for different combinations of roasting duration (4-12 min) and temperature (160-200°C), selected based on central composite rotatable design (CCRD). Pulsed infrared roasting at 178-188°C for 6.8-9.2 min resulted in optimum product quality in terms of color, texture and free fatty acid content. The other parameters such as oil and moisture content, peroxide value and sensory characteristics of roasted nuts are also evaluated for the select temperature-duration combinations. The oil yield increased marginally with roasting duration and temperature. Peroxide number, an indicator of the stability of fat, did not vary during infrared roasting. Groundnuts processed at 180°C for 8 min scored high in terms of sensory attributes. Infrared roasting resulted in better product quality as compared to drum and sand roasting.

Leaching of Sodium Sulphide Roasted Ilmenite Sand

The possibilities of co-leachings of Ti(IV) and Fe(III) from the roasted product of ilmenite sand with sodium sulphide at the optimum conditions by hydrochloric and sulphuric acid were investigated. The leaching was dependent on hydrochloric and sulphuric acid concentrations, temperature and leaching time. The optimum conditions for the best dissolution of Ti(IV) and Fe(III) were: temperature 100°C, time 60 min for 1:1 ilmenite to sodium sulphide weight ratio roasted product and 10 min for 1:2 ilmenite to sodium sulphide weight ratio roasted product, acid concentration 4-6 N and agitation speed 400 rpm. About 95 % Ti(IV) and 93 % Fe(III) dissolutions were obtained from hydrochloric acid leaching and 95 % Ti(IV) and 91 % Fe(III) were obtained from sulphuric acid leaching at a solid to liquid phase ratio (S/L) of 0.10 kg dm-3. Keywords: Ilmenite sand, Roasting of ilmenite sand, Sodium sulphide roasted ilmenite, Leaching of roasted product, Dissolution of titanium and iron. Bangladesh J. Sci. Ind. Res. 42(4), 367-376, 2007