The influence of water content and water activity (a sub(w)) on the concentration of volatile compounds in the head-space vapour over model and food samples was studied. Starch-water model systems and three different food systems (hard cheese, apple puree and raw ham) were prepared with a sub(w) values ranging from 0 to 1. For each sample gas chromatographic analyses of volatiles in the headspace vapour and water activity measurements were carried out. For solid foods at intermediate a sub(w) values the highest volatile concentration in the headspace strongly depended on the availability of water. The head-space volatile concentration decreased rapidly when the water became totally free and the water vapour pressure was close to that of pure water | E' stata studiata l'influenza del contenuto in umidita' e dell'attivita' dell'acqua (a inf(w)) sulla quantita' delle sostanze volatili presenti nel vapore dello spazio di testa di sistemi modello e di alimenti aventi una attivita' dell'acqua nell'intervallo di valori di a inf(w) tra 0 e 1. Sui campioni posti in recipienti chiusi ermeticamente sono state determinate per via gascromatografica le sostanze volatili nello spazio di testa e l'attivita' dell'acqua. La concentrazione delle sostanze volatili nello spazio di testa e' risultata fortemente influenzata dalle proprieta' di adsorbimento dell'acqua da parte delle diverse matrici alimentari. La presenza di sostanze volatili e' stata riscontrata al massimo livello, in tutti i casi esaminati, in corrispondenza dell'inizio del ramo ascendente della isoterma di adsorbimento dell'acqua, per discendere rapidamente ai valori piu' elevati di a inf(w), oltre i quali l'acqua presente nell'alimento diviene totalmente disponibile per agire come solvente

External corrosion of tinplate cans containing food products, although less frequent and comparatively less dangerous than internal corrosion, should anyhow be studied more in depth, since the consumer requires not only high-quality products, but also cans having a good appearance. The objective of this experimental work was to study the influence of the main ions present in cooling waters on the corrosion of metal food cans. After a short introduction on tinplate corrosion phenomena and on the chemical and processing factors affecting it, the results are shown which were obtained from electrochemical corrosion trials performed using model solutions at various concentrations as well as cooling water samples directly taken from food plants. This research work yielded information on the corrosion mechanisms (extent and morphology) of the various species and parameters affecting the aggressivity of industrial waters (presence of additives, free chlorine content and conductivity) | La corrosione esterna delle scatole di banda stagnata contenenti prodotti alimentari, sebbene meno frequente e relativamente meno pericolosa della corrosione interna, deve comunque essere oggetto di maggiore attenzione, in quanto il consumatore richiede, oltre a prodotti di alta qualita', contenitori di aspetto accettabile. Oggetto del lavoro sperimentale e' stato lo studio dell'influenza dei principali ioni presenti nelle acque di raffreddamento sulla corrosione delle scatole metalliche per alimenti. Dopo una breve introduzione sui fenomeni di corrosione della banda stagnata e sui fattori chimici e di processo che la condizionano, il lavoro illustra i risultati ottenuti nelle prove di corrosione elettrochimiche effettuate con soluzioni modello a diverse concentrazioni e con acque di raffreddamento prelevate direttamente presso industrie alimentari. A conclusione della ricerca sono state ottenute informazioni sul meccanismo di corrosione (intensita' e morfologia) delle diverse specie e sui parametri che influenzano l'aggressivita' delle acque industriali (presenza di additivo, concentrazione di cloro libero e conducibilita')

Algae can be used as an ingredient for food production, as well as a source of marine hydrocolloids and various biologically active substances. There is a lack of studies on the significant floral diversity of the northern seas. It justifies the need not only to determine the species composition of common red algae species, but also to scrutinize its chemical composition and methods to obtain sulfated polysaccharides for further use in the food industry. The chemical composition of a natural mixture consisting of two species of red algae – Ptilota serrata and Ptilota gunneri - gathered in the littoral near Bolshoy Solovetsky Island in the period 2019–2023 had been explored. The research demonstrated that there were no significant differences in the content of ash, protein, carbohydrates and fiber in the mixtures, depending on the month of gathering. When developing a production technology for a water-soluble polysaccharide from a P. serrata and P. gunneri mixture, it was revealed that the rational algae pretreatment mode was maintaining the pH level, duration 1 hour, temperature (22 ± 2) deg C. The polysaccharide extraction modes are the following: temperature (120 ± 2) deg C, duration 1 hour and pH medium level 7. To purify the polysaccharide extract, it is most rational to use activated carbon in an amount of 0.5–1.0% by extract weight, duration (60 ± 5) minutes, temperature (98 ± 2) deg C. The water-soluble polysaccharide should be dried using freeze-drying or spray dryers. The authors recommend using a water-soluble polysaccharide from a P. serrata and P. gunneri red algae mixture as a thickener in production such foods as fruit desserts, sauces and jelly-like soft drinks. | Морские водоросли могут использоваться для производства продуктов питания, как источник морских гидроколлоидов и различных биологически активных веществ. Значительное флористическое многообразие северных морей практически не изучено, что обосновывает необходимость не только определения видового состава массовых видов красных водорослей, но и исследования их химического состава и способов получения сульфатированных полисахаридов с целью их дальнейшего применения в пищевой промышленности. Представлены результаты исследования химического состава природной смеси, состоящей из двух видов красных водорослей – Ptilota serrata и Ptilota gunneri, собранных на литорали у о. Большой Соловецкий в период 2019–2023 гг. Показано, что в смесях отсутствуют значимые различия в содержании золы, белка, углеводов и клетчатки в зависимости от месяца их сбора. При разработке технологии получения водорастворимого полисахарида из смеси P. serrata и P. gunneri, установлено, что рациональным режимом предобработки водорослей является поддержание рН среды, продолжительность 1 ч, температура (22 ± 2) град. С. Экстрагирование полисахарида следует проводить при температуре (120 ± 2) град. С, продолжительности 1 ч и рН среды 7. Для очистки экстракта полисахарида наиболее рационально использовать активированный уголь в количестве 0,5–1,0% к массе экстракта, продолжительность (60 ± 5) мин, температура (98 ± 2) град. С. Сушку водорастворимого полисахарида следует проводить с использованием сублимационной или распылительной сушилок. Рекомендовано использовать водорастворимый полисахарид из смеси красных водорослей P. serrata и P. gunneri в качестве загустителя при изготовлении таких пищевых продуктов, как десерты фруктовые, соусы и кисели питьевые.