Frequently asked questions about chlorophyll fluorescence, the sequel

[EN] Using chlorophyll (Chl) a fluorescence many aspects of the photosynthetic apparatus can be studied, both in vitro and, noninvasively, in vivo. Complementary techniques can help to interpret changes in the Chl a fluorescence kinetics. Kalaji et al. (Photosynth Res 122: 121-158, 2014a) addressed several questions about instruments, methods and applications based on Chl a fluorescence. Here, additionalChl a fluorescence-related topics are discussed again in a question and answer format. Examples are the effect of connectivity on photochemical quenching, the correction of F-V/F-M values for PSI fluorescence, the energy partitioning concept, the interpretation of the complementary area, probing the donor side of PSII, the assignment of bands of 77 K fluorescence emission spectra to fluorescence emitters, the relationship between prompt and delayed fluorescence, potential problems when sampling tree canopies, the use of fluorescence parameters in QTL studies, the use of Chl a fluorescence in biosensor applications and the application of neural network approaches for the analysis of fluorescence measurements. The answers draw on knowledge fromdifferent Chl a fluorescence analysis domains, yielding in several cases new insights.Kalaji, H.; Schansker, G.; Brestic, M.; Bussotti, F.; Calatayud, A.; Ferroni, L.; Goltsev, V.... (2017). Frequently asked questions about chlorophyll fluorescence, the sequel. 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Spray drying in food industry

Suszenie rozpyłowe jest techniką, która w w znaczący sposób zmieniła się od czasów jej pierwszych pionierskskich zastososowań w przemyśle spożywczym. W artykule scharakteryzowano podstawowe parametry warunkujące przebieg procesu i przedstawiono zagadnienia związane z suszeniem trzech grup produktów: napojów typu instant, produktów pochodzenia mikrobiologicznego oraz soków owocowych. Omówiono również aktualnie najnowsze kierunki rozwoju tego procesu.Spray drying is a technique which has been significantly modified since its first applications in food industry. In this paper the basic paremeters of spray drying were described, the drying of three groups of products was discussed: instant beverages, products of microbiological origin and fruit juices. Additionally, some curent and the newest trends in spray drying development were also presented

Spray-drying of enzymes: causes of inactivation, methods and mechanisms of stabilizing them

Inaktywacja enzymów wywołana procesem suszenia oraz próby opisu jej przyczyn i mechanizmów są przedmiotem wielu publikacji naukowych. W niniejszym artykule przedstawiono analizę najważniejszych przyczyn inaktywacji oraz podano przykłady badań obrazujących opisane mechanizmy. Do przyczyn tych zaliczono: działanie podwyższonej temperatury, niekorzystny wpływ ubytku wody z układu, niekorzystny wpływ adsorpcji białek na powierzchni międzyfazowej oraz uszkodzenia mechaniczne. Opisano również, oraz zilustrowano przykładami, metody i mechanizmy stabilizacji aktywności enzymów w czasie suszenia rozpyłowego, takie jak: zastępowanie wody, stan szklisty oraz adsorpcja międzyfazowa.Enzyme inactivation generated by the spray drying process and attempts to describe both the possible causes and the mechanisms thereof constitute a subject matter of many scientific papers. In the present paper, the analysis of the most important causes of inactivation is presented, and some examples are given to illustrate the mechanisms described. The causes of inactivation include: impact of increased temperature, adverse effect of removing water from the system, adverse effect of protein adsorption on interfacial surface, and mechanical damages. Some methods and mechanism applied to stabilize the enzyme activity during spray-drying are described and exemplified, such as: water replacement, glassy state, and interfacial adsorption

Właściwości fizyko-chemiczne preparatów miodowych suszonych rozpyłowo

The aim of work was to characterise the physical and chemical properties of spray dried honey preparations and the changes in these properties during storage. Spray drying was performed at inlet air temperature 160 and 200°C, atomising disk speed 32 000 and 38 000 rpm, with the use of two types of carriers: dextrin and maltodextrin. The resulting powders had the desirable physical properties: low water content and activity, complete solubility and low cohesiveness. The powders produced with the use of dextrin had higher hygroscopicity and poorer solubility, they were also characterised by the highest water absorption during storage. Powders obtained with the use of reduced atomisation speed were the most stable in terms of water absorption and the changes of hygroscopicity during storage. Solubility of all powders was stable during storage.Celem pracy było określenie właściwości fizycznych i chemicznych preparatów miodowych suszonych rozpyłowo oraz zmiany tych właściwości w czasie przechowywania. Suszenie rozpyłowe przeprowadzono przy temperaturze powietrza wlotowego 160 do 200°C, szybkość obrotowa dysku rozpylającego wynosiła 32 000 i 38 000 obrotów na minutę, użyto dwóch rodzajów nośników: dekstrynę i maltodekstrynę. Otrzymane proszki miały pożądane właściwości fizyczne: niską zawartość i aktywność wody, całkowitą rozpuszczalność i niską spójność. Proszki wytworzone z wykorzystaniem dekstryny miały wyższą higroskopijność i gorszą rozpuszczalność, charakteryzowały się najwyższą ilością wchłoniętej wody w czasie przechowywania. Proszki otrzymane z wykorzystaniem zmniejszonej szybkości obrotowej dysku rozpylającego były bardziej stabilne pod względem absorpcji wody i zmiany higroskopijności podczas przechowywania. Rozpuszczalność wszystkich proszków była stabilna w czasie przechowywania

Metody suszenia mikroorganizmow i produktow syntezy mikrobiologicznej

Przedstawiono charakterystykę mikroorganizmów i produktów syntezy mikrobiologicznej (jako obiektów suszenia) oraz podstawowe przyczyny degradacji tych materiałów w czasie odwadniania. Zaprezentowano najczęściej stosowane metody suszenia, pozwalające na zachowanie aktywności biologicznej duktów: suszenie rozpyłowe, fluidyzacyjne i sublimacyjne. Wyodrębniono również suszenie na nośnikach, charakterystyczne dla grupy materiałów biotechnologicznych. Opisano także nowe, pozostające w e prób laboratoryjnych, niekonwencjonalne sposoby suszenia.Feature of microorganisms and products of microbiological synthesis as drying objects and basic reasons of the products degradation during dewatering were presented. Most often applied drying methods, which allow of keeping of products biological activity: spray, fluid and freeze drying were described. Drying on carriers, characteristic for biotechnological products, was indicated. Remaining in phase of laboratory tests, unconventional ways of drying were also presented

Effect of kappa carrageenan hydrolysates on limiting excessive ice crystals growth in ice creams

Celem pracy było pozyskanie nowych substancji stabilizujących i zaprojektowanie układu mającego na celu ograniczenie procesu rekrystalizacji w trakcie przechowywania lodów mlecznych. Pierwszy etap badań obejmował proces hydrolizy kwasowej κ-karagenu, z wykorzystaniem H₂SO₄ i HCl. Przy użyciu chromatografii żelowej SEC określono masę cząsteczkową otrzymanych hydrolizatów. Następnie podjęto próbę wykorzystania otrzymanych związków jako stabilizatorów do lodów mlecznych. Kolejnym etapem badań była analiza procesu rekrystalizacji na podstawie fotografii kryształów lodu wykonanych po przygotowaniu lodów mlecznych, po tygodniu oraz po miesiącu ich przechowywania, za pomocą mikroskopu Alphaphot-2 YS2 i kamery Nikon DS-F. W badanych próbkach oprócz κ-karagenu i jego pochodnych zastosowano również dodatek żelatyny, gumy guar, alkoholu i gotowych mieszanek stabilizujących firmy Danisco (DuPont). Hydroliza kwasowa z zastosowanie HCl i H₂SO₄ wpłynęła na redukcję masy cząsteczkowej κ-karagenu ok. 10-krotnie. Na podstawie fotografii kryształów lodu zawartych w lodach mlecznych stwierdzono, że obecność hydrolizatów κ-karagenu miała większy wpływ na ograniczenie procesu rekrystalizacji niż dodatek samego κ-karagenu czy dodatek przemysłowych mieszanek stabilizujących. Po miesiącu przechowania średnica kryształów lodu w próbkach lodów z dodatkiem hydrolizatu κ-karagenu uzyskanego po hydrolizie HCl nie przekroczyła 16 μm, podczas gdy w próbkach z dodatkiem niehydrolizowanego κ-karagenu, po tym samym czasie – przekraczała 25 μm.The objective of the research study was to produce new stabilizing substances and to develop a system to reduce the recrystallization process while storing ice cream products. The first stage of the research comprised an acid hydrolysis process of κ-carrageenan with the use of H₂SO₄ and HCl. A SEC gel permeation chromatography was applied to determine the weight of the hydrolysates produced. Then, an attempt was made to utilize the compounds produced as stabilizers for ice creams. The next research stage was to analyze, with the use of Alphaphot-2 YS2 microscope and Nikon DS-F camera, the process of recrystallization on the basis of the ice crystals images taken instantly after the ice creams were made, after one week and, next, one month of storing them. In addition to κ-carrageenan and its derivatives, gelatin, guar gum, alcohol, and ready-mixed stabilizing mixtures manufactured by Danisco Co. (DuPont) were added to the samples investigated. The acid hydrolysis with the use of H₂SO₄ and HCl caused the molar mass of κ-carrageenan to decrease by ca. 10 times. Based on the images of ice crystals contained in ice cream products, it was found that the presence of κ-carrageenan hydrolysates had a greater effect on reducing the recrystallization process than the addition of κ-carrageenan alone or the addition of industrial compound stabilizers. As regards the ice cream samples with the added κ-carrageenan hydrolysate after hydrolysis with HCl, after one month of storing the ice creams, the equivalent diameter of ice crystals therein did not exceed 16 μm, whereas, as regards the ice cream samples stored for one month and with the non-hydrolyzed κ-carrageenan added, that diameter exceeded 25 μm

Textural characteristics of selected fat blends

Celem pracy było określenie wyróżników tekstury wybranych miksów tłuszczowych za pomocą testów penetracji z próbnikami stożkowym i cylindrycznym oraz w teście smarowności. Pomiary wykonano w kontrolowanych warunkach temperatury w 4 i 20°C. Miksy tłuszczowe zawierały od 62 do 70% tłuszczu ogółem, w tym tłuszcz mleczny stanowił w produkcie od 10 do 52%. Wśród badanych próbek najmniejszą twardością charakteryzowały się miksy, w których w fazie tłuszczowej przeważał tłuszcz mleczny w stosunku do dodanego tłuszczu roślinnego. Duża twardość miksów o zawartości tłuszczu roślinnego powyżej 45% mogła wynikać m.in. z zawartości nasyconych wyższych kwasów tłuszczowych w produkcie. Zastosowanie testu penetracji z wykorzystaniem końcówki stożkowej wpłynęło na większą powtarzalność pomiarów, co ułatwiło interpretację i ocenę tekstury badanych miksów w porównaniu do końcówki cylindrycznej. Smarowność miksów pogarszała się wraz ze wzrostem ich twardości.Spreadable mixed fat product can be based on milk fat blended with vegetable oils or butter blended with vegetable fats. These fat blends are more popular because consumers expectthe products with attractive sensory properties of butter with spreadability typical for margarines. The texture of fat blends is one of most important feature in the quality evaluation. The aim of this study was an instrumental analysis of texture attributes of selected commercial fat blends with total fat content in the range of 62–70%. The content of milk fat in blends ranged from 10 to 52%. Texture of blends were analysed using the penetration tests with a cylinder probe P/5 and also with conical probe P/45C. Spreadability was measured using a TA-HDplus Texture Analyzer with a TTC Spreadability Rig. Thermal cabinet TCHD/LN2 integrated with a texture analyser provided an accurately controlled temperature environment during instrumental tests. The selected texture attributes (hardness, adhesiveness, consistency, stickiness, softness, spreadability) were analysed at temperature of 4 and 20°C. The results obtained at different temperature showed the decrease of hardness and penetration work was observed at room temperature. The lowest hardness was detected for blends with high content of milk fat. The samples with substantial addition of vegetables fats were harder what can be related with their composition e.g. the addition of palm oil can cause the increase of saturated fatty acids. The addition of vegetable oils caused the hardening of blends. The highest hardness and adhesiveness and the lowest spreadability values were recorded for blends with 10% of milk fat and 52% of vegetable oils (palm and linseed oils) as well as for blends of 25% of butter and 45% of vegetable fats. The higher hardness and the lower spreadability of fat blends was observed. It was concluded that the penetration test with a conical probe was well-suited and applicable for measuring the texture attributes of fat blend in comparison to penetration with cylindrical probe. The cone penetration test enabled to assay diversity of blends texture. The changes of penetration force of blends during the period when the samples were removed from refrigeration and brought to ambient temperature were also recorded. The hardness of sample 10/62 (contained 10% of milk fat and 52% of vegetable oils) significantly decreased during the first 20 min of exposure to room conditions. More stable in terms of hardness were blends with higher content of milk fat