Physicochemical characteristics and structural changes of fermented faba bean extrudates prepared by twin-screw extrusion.

In this study, fermented faba bean blends with different locust bean gum (LBG) contents were processed in a co-rotating twin-screw extruder. The effects of extrusion process variables and the LBG level on physicochemical, sensory and structural characteristics of expanded extrudates were investigated. The results showed that physical characteristics of extrudates including expansion, apparent density and texture were significantly affected by variation of screw speed and die temperature, but the effect of LBG level was only significant for expansion and density. FTIR-ATR analysis revealed that a significant change occurred in the protein secondary structure as well as in the short-range ordered molecular structure of starch during fermentation and extrusion. The X-ray diffraction patterns of extrudates exhibited V-type pattern. Microstructure of the extrudates analyzed by FE-SEM exhibited variations in cell size and wall thickness depending on extrusion processing conditions and LBG level, which in turn lead to different textural perceptions.

Statistical investigation of the bioprocess conditions of alkali combined twin-screw extrusion pretreatment to enhance fractionation and enzymatic hydrolysis of bulgur bran.

BACKGROUND: Bulgur bran (BB) is a potential source for the production of value-added products such as fermentable sugars and xylooligosaccharides (XOs). In this study, alkali combined twin-screw extrusion pretreatment was performed and statistically optimized to enhance fractionation and enzymatic hydrolysis of BB. The pretreatment conditions (barrel temperature, screw speed and alkali impregnation) were optimized by Box-Behnken design (BBD) to obtain the highest hemicellulose separation from BB. The obtained fractions were analyzed for the production of fermentable sugars and XOs. RESULTS: The results revealed that twin-screw extrusion of BB performed at 67 °C barrel temperature and 250 rpm screw speed after alkali impregnation at 0.02 g alkali g-1 biomass concentration provided 40.4% higher hemicellulose separation yield compared to the untreated BB. Alkali combined twin-screw extrusion pretreatment increased the enzymatic hydrolysis yield of BB fourfold, whereas a 13-fold increase was achieved after the separation of hemicellulose from pretreated BB. Xylose (X1)-free xylobiose (X2) was the main product after xylanase hydrolysis of hemicellulose fraction. SEM images confirmed the morphological modifications in BB, which were in agreement with the enhanced fractionation performance and the higher enzymatic hydrolysis yield. CONCLUSION: The results of this study suggested that pretreatment by alkali combined twin-screw extrusion followed by alkali extraction could be a reliable and effective process for fractionation of BB and production of fermentable sugars and XOs. © 2022 Society of Chemical Industry.

Impact of tomato pomace powder added to extruded snacks on the in vitro gastrointestinal behaviour and stability of bioactive compounds.

In this study, extruded snacks enriched with tomato pomace powder (TPP) at ratios of 5, 10, 15, and 20% (w/w) were prepared based on some preliminary experiments. The effect of tomato pomace addition to extruded snacks on the total phenolic content, total antioxidant capacity, contents of lycopene and phenolics, as well as their in vitro bioaccessibility; and additionally, physical, textural and sensory properties of the samples were investigated. According to the results, increasing levels of TPP in snacks significantly increased the content of individual phenolics including gallic acid, protocatechuic acid, 2,5-dihydroxybenzoic acid, chlorogenic acid, rutin and quercetin. Similarly, increased amount of TPP in snacks enhanced the bioaccessible protocatechuic acid, chlorogenic acid, rutin and quercetin as well as lycopene (p < 0.05). TPP incorporated snacks displayed lower expansion indices, water absorption index (WAI) and water solubility index (WSI) and lightness; but had higher hardness, redness and yellowness values than the control. However, snacks had acceptable physical and sensory properties when enriched with 10% of TPP. The results suggest that tomato pomace can be added as a functional ingredient to improve the nutritional value of snack products.

Effects of instant controlled pressure drop process on physical and sensory properties of puffed wheat snack.

BACKGROUND: In this study, research on the development of a puffed wheat snack using the instant controlled pressure drop (DIC) process was carried out. Snack products were produced by expanding moistened wheat under various DIC processing conditions in order to obtain adequate puffing, followed by drying in a hot air dryer. The effects of operational variables such as wheat initial moisture content (11-23% w/w, wet basis), processing pressure (3-5 × 102 kPa) and processing time (3-11 min) on the physical (density, color and textural characteristics) and sensory properties of the product were investigated. RESULTS: The physical properties of the wheat snack were most affected by changes in processing pressure, followed by processing time and wheat moisture content. Increasing processing pressure and time often improved expansion and textural properties but led to darkening of the raw wheat color. The most acceptable snack in terms of physical properties was obtained at the lowest wheat moisture content. Sensory analysis suggested that consumer acceptability was optimal for wheat snacks produced at higher processing pressure, medium processing time and lower moisture content. CONCLUSION: The most desirable conditions for puffed wheat snack production using the DIC process were determined as 11% (w/w) of wheat moisture content, 5 × 102 kPa of processing pressure and 7 min of processing time. © 2016 Society of Chemical Industry.

Determination of volatile nitrosamines in various meat products using comprehensive gas chromatography-nitrogen chemiluminescence detection.

An optimized method was developed for the extraction, pre-concentration and analysis of nitrosamines (NAs) in various meat products. Values of reproducibility, linearity, limit of detection (LOD) and limit of quantitation (LOQ) for six NA standards (N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodi-n-propylamine, N-nitrosopyrrolidine, N-nitrosopiperidine, N-nitrosodi-n-butylamine) were determined. The LODs using this method were between 1.66-3.86 and LOQs between 6.96-16.71 µg L(-1). The screening of four different types of meat samples (sausage, salami, sucuk and doner kebab) showed that all samples contained levels of various NAs, identified with high confidence using comprehensive gas chromatography (GCxGC) and a fast responding element specific nitrogen chemiluminescence detector (NCD). The sum of the six NAs were highest in the doner kebab samples, being between 0.51-16.63 µg kg(-1) and were lowest in the sausage samples at 0.45-2.93 µg kg(-1). The described method is simple, rapid, selective and sensitive.