Silkworm pupae, a waste product from the silk production industry, can be an alternative source of edible oil, thus reducing the industry’s waste. In the present work, frozen silkworm pupae were used as raw material to extract oil via an aqueous saline process. The Box–Behnken design (BBD) and response surface methodology (RSM) were used to optimize the extraction process. The extraction conditions with the highest oil yield and a low peroxide value were obtained when using a saline solution concentration of 1.7% w/v, a ratio of aqueous liquid to silkworm pupae of 3.3 mL/g, and a 119 min stirring time at the stirring speed of 100 rpm. Under these conditions, silkworm oil with a yield of 3.32%, peroxide values of approximately 1.55 mM, and an acid value of 0.67 mg KOH/g oil was obtained. The extracted oil contained omega-3 acids (α-linolenic acid), which constituted around 25% of the total fatty acids, with approximate cholesterol levels of 109 mg/100 g oil. The amounts of β-carotene and α-tocopherol were approximately 785 and 9434 μg/100 g oil, respectively. Overall, the results demonstrated that oil extracted from silkworm pupae has good quality parameters and thus can be used as a new valuable source of edible lipids.

Summary This work studied the effects of three sucrose esters (S170, P170 and L195) on the crystallisation of palm olein (PO). The effect of the emulsifiers on the crystallisation behaviour, crystallisation curves, microstructure and polymorphism was investigated. Both S170 and P170 accelerated the early stages, via template effects, but suppressed the later stages of PO crystallisation. The effect on the latter stages was stronger with P170 than S170. In contrast, L195 suppressed PO crystallisation at all time points. Through DSC, S170 and P170 only associated with the high‐melting fraction of PO whereas L195 showed little influence. All SEs exhibited no effect on polymorphism. S170 and P170 greatly reduced PO crystal size but increased crystal number while the L195 increased the crystal size but decreased the crystal number especially at low concentration. Overall, S170, P170 and L195 influence PO crystallisation kinetics but the effect was dependent on the emulsifier concentration.

Introduction Palm oil PO is derived from the mesocarp of the palm fruit and is widely used in food applications. It is semi-solid at room temperature 25 and contains similar levels of saturated and unsaturated fatty acids. Generally, PO presents the crystal habit in β-form, which is usually the most functional polymorph in many fat-based products 1. This characteristic combined with other properties such as plasticity, oxidative stability and trans-fat free ensure its beneficial applications in food products 2. PO may be fractionated into a liquid fraction palm olein: POL and a more solid fraction palm stearin: PS. POL appears clear at ambient temperature of 25 due to its high content of C 18:1 39-45 and C 18:2 10-13 3 and has been identified as a good ingredient for several food formulations. However, its application is often limited by its tendency to form granular crystals and get cloudy at low temperature during longterm storage. The visual observation of these crystals is usually seen as a defect by consumers although there is no deterioration in the oil quality 4 .

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This study provides an evaluation of the use of rheology to characterize soft, semi‐hard, and hard fats in relation to determine the crystallization onset, crystallization behavior, as well as microstructure development using either a plate–plate or a starch pasting cell (SPC). The results from this study demonstrate that when applying rheology to study fat crystallization, the results must be interpreted with care. The application of a plate–plate geometry allowed for sensitive evaluation of the initial nucleation phase, which was not possible with an SPC. Both geometries could provide information on crystallization behavior in terms of one‐step or two‐step crystallization. However, in the late stage of the crystallization process, when the fat crystals form a strong network, the SPC could not describe differences in the rheology of the fat‐crystal network, which was a possibility by the use of a plate–plate geometry. Thus, oscillatory rheology with a suitable geometry can be used to evaluate the entire crystallization process.

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