This study compares the quality of extrudates made from corn grits with the addition of up to 8% of spirulina powder. The sensory properties (shape, color, aroma, taste and crispness), chemicals (content of water, protein, fat, ash, fiber, carbohydrates, carotenoids, chlorophyll and phycocyanin) and physical properties (color, water absorption index, expansion indices, texture and water sorption properties) were determined. It has been found that spirulina-enriched extrudates had slightly lower sensory scores, but the addition of spirulina improved their nutritional value. The contents of protein, ash, fiber and β-carotene increased in extrudates with 8% of spirulina by 34, 36, 140 and 1,260%, respectively. The increasing addition of spirulina caused a decrease in extrudates lightness, an increase in their greenness and yellowness accompanied by a decrease of expansion indices and an increase of softness. Only small differences were found in water sorption properties, suggesting a similar behavior of spirulina-enriched extrudates during storage.

Edible insects are more and more widely researched and presented as a good source of nutrients. Among the available raw materials, cricket powder (CP), obtained from roasted and crushed crickets, deserves attention because it can be used as an ingredient in many food products. The aim of this study was to determine the effect of CP addition on the physical and sensory properties of extruded corn snacks. In the extrusion process, five variants of corn snacks were produced with 2%, 4%, 6%, and 8% additions of CP, and with 8% CP and 2% baking powder. Snacks without CP addition were used as a control (R). The study also evaluated the storage life of the manufactured snack products based on their sorption properties. It was found that increasing the CP content in snacks has a significant effect on their characteristics, with a lower expansion ratio as the result of the higher CP content in the extrudates. CP increased the solubility and decreased the water absorption of the snacks. Color changes were also observed in the produced snacks. The more CP in the recipe, the darker the end product. In addition, the color parameters a* and b* were shifted towards red and blue in cross-sections of snacks with higher percentages of CP. According to the sensory analysis, CP additions up to 6% allow for obtaining sensory-attractive snacks. Statistical analysis of the results showed that the snack parameters, expansion ratio, and water absorption index are of the greatest importance for sensory acceptance. Therefore, when planning the incorporation of CP into this type of product, special attention should be paid to obtaining extrudates with appropriate parameters.

A b s t r a c t. This study evaluated the kinetics of water vapour adsorption on the surface of starch molecules derived from wheat. The aim of the study was to determine an equation that would allow estimation of water content in tested material in any timepoint of the adsorption process aimed at settling a balance with the environment. An adsorption isotherm of water vapour on starch granules was drawn. The parameters of the Guggenheim, Anderson, and De Boer equation were determined by characterizing the tested product and adsorption process. The equation of kinetics of water vapour adsorption on the surface of starch was determined based on the Guggenheim, Anderson, and De Boer model describing the state of equilibrium and on the model of a first-order linear inert element describing the changes in water content over time.

In sea transport, a very important thing is an assignment of cargo to a particular class of storage climate conditions and it is carried out on the basis of the requirements that cargo places upon its storage atmosphere. The water content of black tea must not fall below 2%, as the product otherwise becomes hay-like and its essential oils readily volatilize, while on the other hand, it must not exceed 9% as it then has a tendency to grow mould and become musty. Therefore, tea requires particular temperature, humidity/moisture and possibly ventilation conditions. In this context, tea is a hygroscopic material that has the ability to absorb or desorb water in response to temperature and relative humidity of the atmosphere surrounding it. The moisture content of tea is one of the most important variables affecting its chemical and sensory properties. Therefore, to explore and predict the behaviour during transport of tea, its equilibrium moisture content must be determined for a range of transport temperatures and relative humidities. The present paper focuses on the evaluate the hygroscopic properties of tea from Rwanda with different degree of fragmentation based on isotherms of water vapour sorption and characteristics selected parameters of the surface microstructure determining transport conditions and therefor microbiological stability of teas.

Celem pracy była ocena właściwości fizykochemicznych handlowych odżywek białkowych w proszku. Materiał doświadczalny stanowiły 4 preparaty w formie proszku: izolat białek sojowych, koncentrat białek serwatkowych, białko konopi oraz koncentrat białka grochu. Zakres badań obejmował oznaczanie zawartości i aktywności wody, kąta nasypu i zsypu, gęstości luźnej i utrzęsionej, barwy, właściwości rekonstytucyjnych oraz sorpcyjnych wybranych preparatów, m.in. powierzchni właściwej sorpcji i pojemności warstwy monomolekularnej. Na podstawie przeprowadzonych badań stwierdzono, że oceniane produkty charakteryzowały się różnym poziomem zawartości i aktywności wody, determinowanym składem surowcowym preparatu białkowego w proszku. Najwyższe wartości tych parametrów zaobserwowano w białku konopnym oraz w koncentracie białek grochu. Na podstawie oceny gęstości nasypowej luźnej i utrzęsionej oraz kąta nasypu stwierdzono, że proszki badanych białek cechowała średnia kohezyjność oraz zróżnicowana sypkość. Bardziej korzystnymi właściwościami fizykochemicznymi charakteryzowały się produkty pochodzenia roślinnego. Pomiar kąta zsypu pozwolił na stwierdzenie zależności pomiędzy stosowaną powierzchnią pomiaru a sypkością badanego białka w proszku. Dowiedziono, że największą trwałością przechowalniczą charakteryzowało się białko serwatkowe, natomiast najniższymi wartościami Vm i powierzchni właściwej sorpcji – białko konopne. Powyższe badania pozwoliły określić trwałość przechowalniczą preparatów handlowych białek w proszku produkowanych przemysłowo oraz ocenić ich wstępną przydatność w operacjach manipulacyjnych lub przeładunkowych.