Omega-3 fatty acid imparted good evidence of health benefits. Flaxseed oil, being the richest vegetarian source of alpha linolenic acid (omega-3 fatty acid), was incorporated in cookies by replacing shortening at level of 5 %, 10 %, 20 %, 30 %, 40 % and 50 %. Effect of shortening replacement with flaxseed oil on physical, textural and sensory attributes were investigated. Spread ratio and breaking strength of cookies increased as flaxseed oil level increased. Sensory score was not significantly affected up to 30 % shortening replacement with flaxseed oil as compared with the control cookies. Above 30 % flaxseed oil, sensory score was adversely affected. Fatty acid profile confirmed the enhancement of omega-3 fatty acid from 0 (control) to 14.14 % (30 % flaxseed oil cookies). The poly-unsaturated to saturated fatty acid ratio (P/S) increased from 0.088 (control) to 0.57 while ω -6 to ω -3 fatty acid ratio of flaxseed oil cookies decreased from 4.51 (control) to 0.65 in the optimized cookies. The data on storage characteristics of the control and 30 % flaxseed oil cookies showed that there was significant change in the moisture content, Peroxide value (PV) and overall acceptability (OAA) up to 28 days of storage at 45°C packed in polyethylene bags. Flaxseed oil cookies were acceptable up to 21 days of storage and afterwards noticeable off flavour was perceived.

Flaxseed imparted the evidence of health benefits in human being. Response surface methodology (RSM) was employed to develop flaxseed fortified rice -corn flour blend based extruded product using twin screw extruder. The effect of roasted flaxseed flour (RFF) fortification (15-25 %), moisture content of feed (12-16 %, wb), extruder barrel temperature (120-140°C) and screw speed (300-330 RPM) on expansion ratio (ER), breaking strength (BS), bulk density (BD) and overall acceptability (OAA) score of extrudates were investigated using central composite rotatable design (CCRD). Increased RFF level decreased the ER and OAA score significantly while increased BS and BD of extrudates (p<0.01). Moisture content of extruder feed was positively related to ER (p<0.01) and OAA (p < 0.05) and negatively related to BD (p < 0.01). Extruder barrel temperature was found to be negatively related to ER and OAA (p<0.05) and positively related to BD (p<0.1). Quadratic effect of screw speed was significantly positively related to ER (p < 0.01), BS (p<0.05) and negatively related to BD (p<0.01). 15 % RFF fortification with rice flour, 16 % moisture content (wb) of extruder feed, 120°C extruder barrel temperature and 330 RPM of screw speed gave an optimized product of high desirability with corresponding responses as 3.08 ER, 0.53 kgf BS, 0.106 g.cm −3 BD and 7.86 OAA.

Considering the evidence of flaxseed and its defatted flaxseed meal (DFM) for human health benefits, response surface methodology (RSM) based on three level four factor central composite rotatable design (CCRD) was employed for the development of DFM incorporated cornrice flour blend based extruded snack. The effect of DFM fortification (7.5-20 %), moisture content of feed (14-20 %, wb), extruder barrel temperature (115-135°C) and screw speed (300-330 RPM) on expansion ratio (ER), breaking strength (BS), overall acceptability (OAA) score and water solubility index (WSI) of extrudates were investigated using central composite rotatable design (CCRD). Significant regression models explained the effect of considered variables on all responses. DFM incorporation level was found to be most significant independent variable affecting on extrudates characteristics followed by extruder barrel temperature and then screw rpm. Feed moisture content did not affect extrudates characteristics. As DFM level increased (7.5 % to 20 %), ER and OAA value decreased. However, BS and WSI values were found to increase with increase in DFM level. Based on the defined criteria for numerical optimization, the combination for the production of DFM incorporated extruded snack with desired sensory attributes was achieved by incorporating 10 % DFM (replacing rice flour in flour blend) and by keeping 20 % moisture content, 312 screw rpm and 125°C barrel temperature.

Response surface methodology based at three levels and four factors central composite rotatable design was employed to develop groundnut meal (GM) incorporated extruded snack-food using twin screw extruder. The effect of GM incorporation (15-25%), moisture content of extruder feed (14-18%), screw speed (300-330 rpm) and barrel temperature (110-130 °C) on responses like expansion ratio (ER), breaking strength (BS), water solubility index (WSI) and overall acceptability (OAA) score of extrudates. A second-order polynomial model was used to study and explain the relationships between the responses and independent variables. GM content was found to be the most significant variable as it affected negatively ER and OAA (p \ 0.01) while positively BS (p \ 0.01) and WSI (p \ 0.1). Moisture content significantly affected negatively on ER (p \ 0.05), WSI (p \ 0.01), OAA (p \ 0.05) and positively on BS (p \ 0.01). Screw speed significantly affected negatively ER (p \ 0.05), OAA (p \ 0.01) and positively BS (p \ 0.05). Barrel temperature did not affect significantly on the responses within experimental levels. By employing graphical superimposition GM content of 20%, moisture content of 15%, screw speed of 309 rpm and barrel temperature of 130 °C were optimized. Extruded snackfood at optimized variables showed higher protein and fiber content as compared with control.

Attempts were made to understand the drying kinetics, different heats involved, and change in physiochemical properties during Refractance Window (RW) drying of strawberry puree on an in‐house fabricated RW drier. RW drying of puree was conducted at 75°C water temperature with 1.5 mm thickness. The drying was carried out from initial moisture content 614% (db) to 5.1% (db) with1.2 m/s exhaust air velocity. RW drying took place only in the falling rate period. The sensible heat of strawberry puree, convective heat loss from puree surface to air, and convective heat loss from the bottom surface (hot water to air) of the dryer were 70, 205, and 61.96 W, respectively. The evaporative capacity of 5.28 kg m−2 hr−1 was calculated at experimental parameters. This confirms that the drying system is advantageous. RW dried strawberry puree was rehydrated as exact of fresh strawberry puree considering total solids. Total phenolic content and ascorbic acid were significantly (p < .05) reduced from 246.33 mg gallic acid equivalent (GAE) (fresh strawberry puree) to 204.67 mg GAE per 100 g (reconstituted RW dried strawberry puree); 33.31–28.54 mg/100 g, respectively. Color characterization through L*, a*, b*, darkness factor (b*/a*), chroma (C), and hue angle (h*) revealed that reconstituted RW dried puree sample was darker compared with fresh puree. Practical Applications Among various drying methods of fruit purees, hot air drying is the most widely used. It results in an unpleasurable taste and color. During the falling rate drying period, the less thermal conductivity of fruit puree restricts heat transfer in conventional drying. Refractance Window (RW) drying adopts low‐temperature drying for less time, which leads to advantages like effective and economical drying. RW drying technology can be promising at the commercial level in product quality and much‐reduced production cost.