To study the physicochemical properties of sesame paste produced by a novel process technology-ball milling, the effects of different ball milling times (8, 16, 24, 32, and 40 min) at 650 rpm on particle size, texture, rheological properties, volatile compounds, consumer sensory evaluation, and microstructure of sesame paste were investigated. The results showed that ball milling has no significant differences in proximate composition and colour of sesame paste, but the D90 value of particle size decreased to 32.04 μm. Compared to others, the sesame paste ball-milled for 8 min has the highest viscosity of 277.195 gÁs. The sesame paste obtained by ball milling for 32 and 40 min produced 55 and 56 volatile compounds, respectively. Regardless of male and female, sesame paste obtained by ball milling for 24, 32, and 40 min have high overall acceptability. This investigation shows that ball milling is a new technology of potentially great value in the industrial production of sesame paste, which can be used to produce high-quality sesame paste with specific characteristics.

Sesame hull is a byproduct of sesame processing and is currently treated as waste, but it could be an important source of pectic polysaccharides. To increase the value of the sesame crop, pectic polysaccharides were extracted from sesame hull using four different chelators, namely trans-cyclohexane-1,2diamine tetraacetic acid (CDTA), ethylene diamine tetraacetic acid (EDTA), sodium tripolyphosphate (STLP), and sodium hexametaphosphate (SHMP), which were named CSP, ESP, STP, and SHP, respectively. Physicochemical and functional properties were assessed. SHP mainly contained homogalacturonan (HG) linear regions but the others had more branching with rhamnogalacturonan (RG-I) as the predominant region. CSP showed the highest molecular weight (155 kDa) with a smooth surface. The molecular weight of ESP, STP, and SHP ranged from 40 kDa to 90 kDa and presented cracked surfaces. Furthermore, CSP had the highest oil holding capacity (9.03 g oil g −1 dry matter). ESP showed Newtonian-fluid characteristics (n = 1.06) and weaker thermal stability than others. STP had the highest viscosity and good emulsifying stability in concentrations of 1% and 2%. SHP showed excellent water holding capacity, foaming capacity, emulsifying stability, and antioxidant activity. This study provides valuable information for selecting a suitable chelator to extract desirable pectic polysaccharides from sesame hull waste.

ate for traditional oils (soybean, corn, canola, etc.) but not for tigernut oil, because tigernut meal contains relatively high levels of starch (up to 30％) , which is readily gelatinized and/or denatured 7,8) . Therefore, research on the separation technologies of tigernut oil has focused on coldpressing 9) and subcritical fluid extraction 5) . Mechanical cold pressing is easier to operate with many advantages over subcritical extraction, especially in retaining the natural compositions and flavor of the oil. However, the oil yield from tigernut is relatively low in cold-pressed extraction, which is potentially due to the partial denaturation of tigernut starch 10,11) . Because of its high yield and low risk of starch denaturation, subcritical fluid extraction is attracting increasing attention and was used for this study. For this extraction method, different low-boiling solvents, such as n-butane, n-propane, dimethyl ether and tetrafluo-Abstract: In this study, tigernut oil was extracted from tigernut meal by subcritical n-butane extraction with the assistance of microwave pretreatment. Effects of microwave pulse duration, particle size of tigernut meal, and subcritical extraction variables (temperature, time, solid-liquid ratio, number of extraction cycles) on extraction efficiency were examined by single-factor experiments and Response Surface Methodology (RSM) modeling. The results indicate that microwaving (560 W, 6 min) significantly increased the subcritical extraction efficiency. The variation of extraction yield could be interpreted as a nonlinear function of extraction time, temperature and liquid-solid ratio. Changing the independent variables could affect the oil extraction efficiency. The subcritical extraction of tigernut oil with a liquid-solid ratio of 3.62 kg/(kg of tigernut meal) at a temperature of 52℃ for 32 min after three extraction cycles produced the most oil, and a maximum yield (24.736%) of tigernut oil was achieved. The ratio of unsaturated to saturated fatty acids (4.68 UFA/SFA), low acid value (3.30 mg KOH/g oil), low peroxide value (0.28 meq.kg -1 ), and preponderance of oleic acid indicate a high-quality oil. To describe the extraction kinetics, a modified Brunner's mathematical model was used. The model fit the experimental data well over the entire operating range, and the explanation coefficient exceeds 96%. Our results can be used to develop an optimized method for subcritical fluid extraction of tigernut oil and can move industry further toward implementing microwave-assisted subcritical extraction in oil processing.

Summary This study investigated the structural changes of sesame kernel cellulosic polysaccharides during roasting and identified the volatile products produced from the degradation of cellulosic polysaccharides. The results showed that rhamnose and galacturonic acid of cellulosic polysaccharides were more susceptible to non‐enzymatic browning reaction than glucose. The degradation of cellulosic polysaccharides in the roasting temperature range of 180–220°C resulted in decreasing in their molecular weight from 163 270 to 125 477 Da. The crystallinity increased from 16.4% to 32.5% revealing that mainly the amorphous regions of cellulosic polysaccharides were degraded during roasting. In addition, the volatiles from degradation of the amorphous region were rich in aldehydes (10.17–33.33%) and furans (12.84–41.55%). This study provides a new perspective for improving the quality of sesame kernel products in the food industry.

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