Kansen voor fruit in openbaar groen?

Heel wat steden en gemeenten hebben fruit in hun openbaar groen. De verantwoordelijken voor het groen van de steden en gemeenten geloven dat fruit in het openbaar domein een meerwaarde kan zijn, vooral op vlak van educatie, beleving en sociale cohesie. Fruitproductie op zich is hieraan duidelijk onder -geschikt. Tegelijkertijd geven ze aan dat er nood is aan kennis en ondersteuning rond fruit. Joris Dewinter, Master of Science in de Biowetenschappen: Land- en Tuinbouw aan UGent, schreef voor zijn masterproef 208 steden en gemeenten aan, verspreid over Vlaanderen. Daarvan wensten er 81 deel te nemen. Uiteindelijk werden er 56 bevraagd in een “semi-gestructureerd” interview

Stability of semi-liquid shortenings related to their composition and storage temperature

Semi-liquid shortenings are increasingly being investigated as alternatives for butter and margarine in industrial bakery applications driven by the health concerns related to the intake of saturated fatty acids. In semi-liquid shortenings, a low amount of lipid hardstock will form a (gelled) three dimensional network that entraps the liquid oil. Hereby, the ability to retain the liquid oil inside the network or the oil binding capacity, the overall rigidity and the ability to recover when sheared are of main importance. Before applying the semi-liquid shortenings to bakery applications, these are stored at a certain temperature. During this storage period, undesired changes like oiling off and/or softening might occur. Therefore, research about their structural changes upon storage is crucial. In this research, the stability of four dynamically produced semi-liquid shortenings was investigated. All semi-liquid shortenings contained 6% hardstock in rapeseed oil, two of them were triglycerides (TAG) and two were monoglycerides (MAG). Within each type (TAG – MAG), one was based on hydrogenated palm oil and one on hydrogenated rapeseed oil. The semi-liquid shortenings were stored at 5, 15 and 20°C for 8 week and analyzed after three time points (1 week, 4 weeks, 8 weeks) with rheology (amplitude sweep, flow measurements, thixotropy), polarized light microscopy (PLM), oil binding capacity (OBC) test, differential scanning calorimetry (DSC) and X-ray scattering techniques (XRS). It was found that the rigidity and rheology of the TAG-based shortenings was more impacted by storage temperature compared to the MAG-based ones. For the TAG-based shortenings, the rigidity was higher when stored at higher temperatures (G*20°C > G*15°C > G*5°C). Additionally, flow curves indicated higher values for the yield and flow stress. Storage at 5°C resulted in a flow curve with a traditional shear thinning behavior, while storage at 15 and 20°C resulted in the presence of an overshoot. When comparing the palm-based shortenings with the rapeseed-based ones, it was found that the former ones showed a higher rigidity and yield stress. However, they had a lower recovery capacity in the three step thixotropy test. Generally, no drastic decrease in the oil binding capacity and rigidity were found as function of the storage time. This showed that the semi-liquid shortenings were stable up to 8 weeks of storage, which is an important quality characteristic for their applicability in the food industry

Effect of temperature during production and storage of monoglyceride oleogels

Oleogelation is a promising approach to reduce the amount of saturated fatty acids is solid-like fats without losing its structure. Within the field of oleogelation, different hardstocks are used to structure the fat mixture that is rich in unsaturated fatty acids. Different hardstocks requires different structuring routes to form a three dimensional network that entraps the liquid oil. One of the promising methodologies is the use of monoglycerides (MAG) given their ability to form a gel at low concentrations. This research includes a follow-up study of two dynamically produced MAG-based oleogels. Both oleogels contained 6% of a monoglyceride hardstock (fully hydrogenated rapeseed oil) in rapeseed oil and were stored at 5, 15 and 20°C for 8 weeks. Differences in the cooling rate during production resulted in differences in the formation of the fat crystal network that was analyzed with polarized light microscopy (PLM), rheology and oil binding capacity (OBC) test after a storage time of 1 week, 4 weeks and 8 weeks. Generally, the differences between the two oleogels were more pronounced compared to the differences as function of the storage time and temperature. The microstructure of the oleogel produced with the lowest cooling rate (MO1) showed large crystals compared to the dense crystal network of MO2. These large crystals of MO1 were not able to hold the liquid oil resulting in an oleogel with a low oil binding capacity, rigidity and yield stress. These results showed that the stability of monoglyceride oleogels largely depends on the production process and less on the storage conditions

Microstructure development in semi-liquid shortenings upon storage

Saturated fats are widely used as an ingredient in food to obtain the desired organoleptic properties (mouthfeel, texture and aroma release). Although this type of fat is wanted in many applications, its intake needs to be reduced due to the negative effect of the saturated fatty acids on cardiovascular diseases. In order to maintain the desired properties while lowering the amount of saturated fatty acids, gelled oil systems can be used and structured to behave similarly. Oleogelation is an oil structuring technique in which liquid oil is embedded in the fat crystal network of a hardstock. The production of (semi-liquid) shortenings is an example of oleogelation. The term ‘shortening’ is derived from ‘the shortenings effect’ or the ability to weaken, lubricate or shorten the structure to obtain the desired texture. Shortenings have a viscoelastic behavior and their structure is largely dependent on their composition and processing conditions, resulting in a large field of application. This research evaluated the microstructure development in semi-liquid shortenings (6% hardstock in rapeseed oil) upon storage. The shortenings, produced at an industrial pilot plant, were stored at 5, 15 and 20°C and evaluated from nano- tot macroscale with (ultra-)small and wide angle X-ray scattering, differential scanning calorimetry, rheology, oil binding capacity test and polarized light microscopy at week 1, 4, 8, 13 and 27 during storage. The aim was to investigate the influence of six different hardstocks on the properties (from nanoscale to macroscale) of the shortening and their behavior upon storage

Multiscale analysis of monoglyceride oleogels during storage

Oleogelation offers the possibility to reduce the saturated fatty acid (SAFA) content while maintaining the desired organoleptic properties. Hereby, SAFA are replaced by other structurants which can create a three-dimensional network that immobilizes the liquid oil. Depending on the type of structurants, different structuring routes are identified. The use of monoglycerides (MAGs) as structurants is a promising approach thanks to their great self-assembling properties. However, implementation into the food industry is still hampered due to insufficient characterization. This research includes a multiscale analysis of two dynamically produced MAG-based oleogels as a function of the storage time (up to 8 weeks). Slight differences in the production process resulted in differences in techno-functional properties between the MAG-based oleogels MO1 and MO2. MO1 consisted of larger crystals, which resulted in a lower rigidity, lower stability and lower oil binding capacity compared to the other oleogel (MO2). On the nanoscale, it was found that the crystal nanoplatelets (CNPs) of MO1 contained a higher number of lamellae compared to the MO2. Additionally, the results obtained with ultra-small angle X-ray scattering indicated a larger equivalent diameter for the CNPs of MO1. As a function of the storage time, both oleogels did not show major structural changes up to 8 weeks of storage.</jats:p

Multiscale analysis of monoglyceride oleogels during storage

Oleogelation offers the possibility to reduce the saturated fatty acid (SAFA) content while maintaining the desired organoleptic properties. Hereby, SAFAs are replaced by other structurants which can create a three-dimensional network that immobilizes the liquid oil. Depending on the type of structurants, different structuring routes are identified. The use of monoacylglycerols (MAGs) as structurants is a promising approach thanks to their great self-assembling properties. However, implementation into the food industry is still hampered due to insufficient characterization. This research includes a multiscale analysis of two dynamically produced MAG-based oleogels (6% MAGs in oil, MO1 and MO2) as a function of the storage time (up to 8 weeks). Slight differences in the production process resulted in pronounced differences in techno-functional properties of the MAG-based oleogels. MO1 consisted of larger crystals, which resulted in a lower rigidity, reduced stability, and lower oil binding capacity compared with the other oleogel (MO2). On the nanoscale, it was found that the crystal nanoplatelets (CNPs) of MO1 contained a higher number of lamellae compared with MO2. Additionally, the results obtained with ultra-small angle x-ray scattering indicated a larger equivalent diameter for the CNPs of MO1. As a function of the storage time, both oleogels did not show major structural changes up to 8 weeks of storage