The increasing production of edible insects on an industrial scale makes it crucial to implement appropriate technologies after harvesting to process safe and high quality insect products. The aim of this work was to compare the impact of different drying treatments used in the production of flour from Tenebrio molitor larvae. The larvae were subjected to freeze-drying (FD), conventional drying (CD), microwave drying (MWD), microwave drying without freezing prior blanching (MWDL), and microwave drying with addition of 0.1% butylated hydroxytoluene (BHT) during the blanching of the larvae (MWDA). The studied parameters included water activity (a_w), instrumental colour, chemical composition, lipid oxidative processes, antioxidant activity, as well as microbiological status. The freeze-drying and conventional drying of the larvae reduced the a_w of the derived flours (p < 0.0001); however, their nutritional profile revealed lower protein (p < 0.0001) and considerably higher fat content (p < 0.0001) compared to the flours after microwave treatments. The conventional drying and microwave treatment with BHT induced significantly darker colour (p < 0.0001) in comparison to the other methods. Despite the advantages of the microwave drying as a fast and energy efficient method, it displayed some negative effects associated with low lipid stability such as higher acid value (AV) and secondary products of lipid oxidation (TBARS) (p < 0.0001). This was also observed in the MWDA flour, indicating a certain pro-oxidative effect of the BHT. Regardless of the drying method, all the flours had a low microbial load.

Tenebrio molitor is considered a sustainable protein source for diets in poultry. It has been investigated in regard to the performance, health status, and product quality in different poultry species. This study was designed to evaluate the effect of low-fat Tenebrio molitor meal (LFTM) included in the broilers’ diet on the growth performance and carcass composition of the birds. The trial was conducted at the Institute of Animal Science-Kostinbrod, Bulgaria. A total of 120 male one-day-old Ross 308 broilers were allocated to 5 groups. After an adaptation period of 14 days, the birds were fed a basal diet (C) and diets including LFTM in amounts of 2.5% (T2.5), 5% (T5), 7.5% (T7.5), and 10% (T10). The growth performance of the birds was measured during the trial. At 35 days of age, 8 birds per group were slaughtered, and their carcass quality was evaluated. We found a linear response of BWG and FCR towards the inclusion of Tenebrio molitor meal (TM) in the diet. For the whole period (14–35 d), the BWG decreased (p = 0.0002), while the values of FCR increased (p = 0.0001) with the increase in the levels of the insect meal. The doses of 7.5% and 10% of the insect meal were associated with lower carcass weight and also decreased the yield of the breast. The results of the study indicated that the incorporation of LFTM, especially in amounts of 7.5–10%, could not be appropriate for broilers due to adverse effects on the growth performance and carcass composition.

An experiment with male layer-type chickens of the Lohmann Brown Classic breed was carried out at the Institute of Animal Science-Kostinbrod, Bulgaria, aiming to investigate the effect of age at slaughter on the meat quality. The birds were reared in a controlled microclimate, with an initial stocking density of 22 birds/m². At five weeks of age, fragmentation of the stocking density was applied, decreasing the number to seven birds/m². Chickens were slaughtered at five and nine weeks of age at an average live weight of 329 g and 1096 g, respectively. After slaughter, 10 chickens from each age group were subjected to analysis to determine the quality of breast and thigh meat. The results of the study showed that the age affected the meat quality parameters of the male layer-type chickens and its effect differed between the breast and thigh. The chickens slaughtered at nine weeks of age displayed a lower pH but darker meat color (p < 0.001) than those slaughtered at five weeks. Furthermore, the older birds showed a significant decrease in the intramuscular fat content in thigh meat (p < 0.01) and a tendency for diminishing in breast meat. This decrease corresponded to the lower percentage of monounsaturated fatty acids (MUFA) in the meat of the nine-week-old chickens (p < 0.01). On the other hand, the meat of the older chickens displayed a higher content (p < 0.01) of polyunsaturated fatty acids (PUFA), especially n-6, leading to a considerably higher n-6/n-3 ratio.

The objective of this study was to explore the effect of 24 and 48 h alkaline (2% pentasodium tripolyphosphate), acid (2% sodium lactate), and water-oil marinating (water : sun flavor oil = 1 : 1 and 2% salt) as well as brine soaking (2% salt) on microstructure, changes in protein, and lipid fractions and technological properties of sheep (m. Longissimus dorsi). Strong myofibrillar fragmentation after 48 h alkaline marinating was observed. Significant swelling and increasing of spaces between myofibrils were found after 24 h brine soaking. Marinating in water-oil emulsions did not show a significant impact on the muscle microstructure. Alkaline and acid marinating as well as salt soaking promote the myofibrillar protein solubility and increased the free amino nitrogen content. After 24 h acid and 48 h alkaline marinating SDS-PAGE electrophoresis showed increasing of 25–30 kDa protein bands. The results obtained for the lipid and protein oxidation confirm prooxidant action of the sodium lactate (2%) and antioxidant effect of polyphosphates (2%) in marinated sheep.

Background. The aim of this study was to explore the infl uence of acid, alkaline and water-oil marinating on morphological changes and sensory properties of horse meat (m. Longissimus dorsi).Material and methods. Nine samples (C – control stored in air, AL – alkaline marinated in 2% polyphosphates and 2% sodium chloride brine solution, AC – acid marinated in 2% sodium lactate and 2% sodium chloride brine solution, WO – marinated in water-oil emulsion (50/50) contained and 2% sodium chloride and SC – marinated in 2% sodium chloride brine solution) were examined. After 24 h and 48 h of marinating changes in morphology of marinated meat, pH and sensory properties of raw and roasted samples were established.Results. It was determined that sensory properties (aroma, fl avor and tenderness) after roasting were classifi ed as follows: AL48 > AL24 > AC24 > AC48 > SC48 > SC24 > WO24 > WO48 > С. Meat tenderness in AL48, AL24, AC24 and AC48 showed better results due to stronger morphological changes in connective and muscle tissues. Alkaline solutions were more suitable for horse meat marinating compared to acid solutions and the possible reason for strong action of alkaline solutions was lower internal meat pH.Conclusions. Alkaline marinating should be conducted for 24 h because after 48 h the meat acquires a soft and unusually tender texture. Water-oil marinating was not appropriate for horse meat.