Bovine Serum Albumin Rejection by an Open Ultrafiltration Membrane: Characterization and Modeling.

The classic application of ultrafiltration (UF) is for the complete retention of proteins, and in that situation, the transport behavior is well established. More open membranes with fractional retention are used when separating different proteins. However, protein transport has not been well documented yet in the literature. The bovine serum albumin (∼69 kDa) observed rejection ranges from 0.65 to 1 using a 300 kDa molecular weight cut-off membrane at different pH, ionic strength, and pressure. We demonstrated that, especially with open UF, the transport of proteins through the membrane is dominated by advection, with insignificant diffusion effects (p value > 0.05). We showed that with open UF, retention is not only caused by size exclusion but also to a large extent by electrostatic interactions and oligomerization of the proteins. Mass transfer in the polarization layer was relatively independent of the pH and ionic strength. It was underestimated by common Sherwood relations due to a relatively large contribution of the reduction in the flow turbulence near the membrane by the removal of fluid through the membrane. We propose a model that allows relatively quick characterization of the rejection of proteins without prior knowledge of the pore sizes and charges based on just a limited set of experiments. Therefore, protein rejection with the open UF system can be targeted by tuning the processing conditions, which might be useful for designing protein fractionation processes.

Quantifying techno-functional properties of ingredients from multiple crops using machine learning.

Food ingredients with a low degree of refining consist of multiple components. Therefore, it is essential to formulate food products based on techno-functional properties rather than composition. We assessed the potential of quantifying techno-functional properties of ingredient blends from multiple crops as opposed to single crops. The properties quantified were gelation, viscosity, emulsion stability, and foaming capacity of ingredients from yellow pea and lupine seeds. The relationships were quantified using spline regression, random forest, and neural networks. Suitable models were picked based on model accuracy and physical feasibility of model predictions. A single model to quantify the properties of both crops could be created for each techno-functional property, albeit with a trade-off of higher prediction errors as compared to models based on individual crops. A reflection on the number of observations in each dataset showed that they could be reduced for some properties.

Recovery of lactose from simulated delactosed whey permeate by a low-temperature crystallization process.

Delactosed whey permeate is the mother liquor/by-product of lactose manufacture, but it still contains around 20 wt% lactose. The high mineral content, stickiness, and hygroscopic behavior prevent further recovery of lactose in the manufacturing process. Therefore, its use is currently limited to low-value applications such as cattle feed, and more often it is seen as waste. This study investigates a new separation technique operating at sub-zero conditions. At low temperature, precipitation of calcium phosphate is expected to be reduced and the lower solubility at sub-zero temperature makes it possible to recover a large portion of the lactose. We found that lactose could be crystallized at sub-zero conditions. The crystals had a tomahawk morphology and an average size of 23 and 31 µm. In the first 24 h, the amount of calcium phosphate precipitated was limited, whereas the lactose concentration was already close to saturation. The overall rate of crystallization was increased compared with the crystals recovered from a pure lactose solution. Mutarotation was rate limiting in the pure system but it did not limit the crystallization of lactose from delactosed whey permeate. This resulted in faster crystallization; after 24 h the yield was 85%.

Scaling up continuous eutectic freeze crystallization of lactose from whey permeate: A pilot plant study at sub-zero temperatures.

Eutectic freeze crystallization is explored as an alternative to the state-of-the-art evaporation process for the recovery of lactose from whey permeate. At the so-called eutectic freezing point, both water (the solvent) and lactose (the solute) crystallize and can be removed continuously while continuously feeding whey permeate. This continuous process is demonstrated on a pilot scale at sub-zero temperatures. In the first instance, only freeze concentration of whey permeate took place at -4 °C. It was possible to reach a lactose concentration of 30 wt% and hardly any nucleation was observed. The resulting ice had high purity, with a lactose concentration of ±2 wt%. Next, the eutectic phase was reached, and lactose and ice crystallized simultaneously and were continuously removed from the system, the resulting crystals had parallelogram morphology with an average size of 10 µm. Ice was recovered at a rate of 60 kg/h and lactose was recovered at a rate of 16 kg/h, yielding over 80% of the feed lactose. A conceptional design was proposed for an improved yield and reduction of energy. Yields of at least 80% and up till 95% could be achieved. Compared to the state-of-the-art mechanical vapor recompression (MVR), EFC is 80% more energy efficient.

Structure analysis of multi-component pastes - The effect of water distribution on the rheological properties.

Techno-functional properties of multi-component blends and ingredients are determined by the contribution of each ingredient and the water distribution between those ingredients in the blends. However, ingredients can consist of multiple components, which should be considered to better understand the properties of ingredients and blends thereof. Recently, empirical models were used to describe the viscosity of mildly refined ingredient blends. While many compositions were described well by the empirical models, blends with high fiber contents were not predicted sufficiently well. Therefore, in this research, the multi-component blends of commercial pea protein, pea starch, and pea fiber isolates were investigated on their rheological properties as a function of dry matter content. The same properties were then measured for blends of two of these isolates mixed in different ratios. From the rheological experiments, estimations of the water distribution were made with the polymer blending law. The results were compared with CLSM images. A quantitative analysis of the CLSM images mostly confirmed the model outcomes. The isolate ratio could describe the isolate blends sufficiently well, meaning that it was not necessary to know the exact compositions of the ingredients. It was concluded that changes in meso-structure of the blends, for example a phase transition at high fiber contents, caused the lower predictability by the recently published empirical viscosity models. This study demonstrates that the water distribution in multi-component blends plays a crucial role for their viscoelastic properties and the contribution of the individual isolates and components. Moreover, these polymer blending laws that include water distribution provide extra mechanical insights into the fraction behavior in multi-component blends.

Functionality-driven food product formulation - An illustration on selecting sustainable ingredients building viscosity.

Currently, food industries typically favour formulation of food products using highly refined techno-functional ingredients of high purity. However, there is a growing interest in less pure techno-functional ingredients with a lower degree of refining as they deliver the same functional properties with reduced environmental impact. We propose that instead of selecting formulations based on purity, they should be selected based on their techno-functional properties. This article illustrates that the shift in perspective may increase the sustainability of food production. The functionality-driven product formulation is explored through a case study in which yellow pea ingredients are selected to increase the viscosity of a salad dressing. The relation between the ingredients (in terms of composition; protein, starch fibre, and a residual fraction) and the final viscosity was quantified and validated using multiple linear regression. The model described the observations well: the final viscosity is mostly dominated by the starch content; protein content has only a marginal impact; and dietary fibre contributes to viscosity with an antagonistic effect with starch. Based on the multiple linear regression model and further formulation optimisation, we identified various combinations of ingredients (with either a high or low degree of refining) that would result in the target final viscosity. An evaluation of the global warming potential of all blends showed that the desired viscosity could be achieved using only isolates, as well as by using only mildly refined fractions. The latter is associated with a global warming potential that is 80% lower than the one based on isolates. This case study demonstrates the proof of concept for this approach, showing it can aid in identifying alternative product formulations with similar techno-functional properties but with a higher sustainability.

Separation of Fructose and Glucose via Nanofiltration in Presence of Fructooligosaccharides.

Fructose and glucose are commonly present together in mixtures and may need to be separated. Current separation methods for these isomers are complex and costly. Nanofiltration is a cost-effective method that has been widely used for separating carbohydrates of different sizes; however, it is not commonly used for such similar molecules. Here, we report the separation of fructose and glucose in a nanofiltration system in the presence of fructooligosaccharides (FOS). Experiments were performed using a pilot-scale filtration setup using a spiral wound nanofiltration membrane with molecular weight cutoff of 1 kDa. We observed three important factors that affected the separation: (1) separation of monosaccharides only occurred in the presence of FOS and became more effective when FOS dominated the solution; (2) better separation was achieved when the monosaccharides were mainly fructose; and (3) the presence of salt improved the separation only moderately. The rejection ratio (Rf/Rg) in a fructose/glucose mixture is 0.92. We reported a rejection ratio of 0.69, which was observed in a mixture of 50 g/L FOS with a fructose to glucose ratio of 4.43. The separation is hypothesized to occur due to selective transport in the FOS layer, resulting in a preferential binding towards fructose.

Are axial and radial flow chromatography different?

Radial flow chromatography can be a solution for scaling up a packed bed chromatographic process to larger processing volumes. In this study we compared axial and radial flow affinity chromatography both experimentally and theoretically. We used an axial flow column and a miniaturized radial flow column with a ratio of 1.8 between outer and inner surface area, both with a bed height of 5 cm. The columns were packed with affinity resin to adsorb BSA. The average velocity in the columns was set equal. No difference in performance between the two columns could be observed. To gain more insight into the design of a radial flow column, the velocity profile and resin distribution in the radial flow column were calculated. Using mathematical models we found that the breakthrough performance of radial flow chromatography is very similar to axial flow when the ratio between outer and inner radius of the radial flow column is around 2. When this ratio is increased, differences become more apparent, but remain small. However, the ratio does have a significant influence on the velocity profile inside the resin bed, which directly influences the pressure drop and potentially resin compression, especially at higher values for this ratio. The choice between axial and radial flow will be based on cost price, footprint and packing characteristics. For small-scale processes, axial flow chromatography is probably the best choice, for resin volumes of at least several tens of litres, radial flow chromatography may be preferable.

Model-based high-throughput process development for chromatographic whey proteins separation.

In this study, an integrated approach involving the combined use of high-throughput screening (HTS) and column modeling during process development was applied to an industrial case involving the evaluation of four anion-exchange chromatography (AEX) resins and four hydrophobic interaction chromatography (HIC) resins for the separation of whey proteins having close pIs. From the HTS data, one resin of each type was selected (Capto Q and Octyl Sepharose 4 FF). Next, batch uptake experiments were performed to determine the adsorption isotherms of the major whey proteins on the selected resins, followed by isotherm parameters regression. Using the obtained isotherm parameters, the candidate chromatographic operations were modeled and experimentally validated. Finally, these were model-optimized and evaluated based on their optimized performances. In this example, Capto Q performed much better than Octyl Sepharose 4 FF in terms of column capacity, loading, throughput and productivity; hence, Capto Q was selected as the resin of choice for whey proteins separation. This operation was further scaled up from the lab scale (1 mL) to a preparative scale (35 L), with reproducible column elution profile. By this approach, a much wider space of operating variables could be investigated, thereby increasing the chances of finding the ideal operating conditions while keeping experimentation to the minimum.

Perspectives for the industrial enzymatic production of glycosides.

Glycosides are of commercial interest for industry in general and specifically for the pharmaceutical and food industry. Currently chemical preparation of glycosides will not meet EC food regulations, and therefore chemical preparation of glycosides is not applicable in the food industry. Thus, enzyme-catalyzed reactions are a good alternative. However, until now the low yields obtained by enzymatic methods prevent the production of glycosides on a commercial scale. Therefore, high yields should be established by a combination of optimum reaction conditions and continuous removal of the product. Unfortunately, a bioreactor for the commercial scale production of glycosides is not available. The aim of this article is to discuss the literature with respect to enzymatic production of glycosides and the design of an industrially viable bioreactor system.

Chemical and sensory evaluation of crude oil extracted from herring byproducts from different processing operations.

Fish oils extracted from marinated herring (frozen and unfrozen) byproducts and maatjes herring byproducts were evaluated on their chemical and sensory properties. The obtained crude oils had very low content of copper (<0.1 mg/kg oil), and iron values were 0.8, 0.1, and 0.03 mg/kg oil, respectively, for oil from maatjes and frozen and fresh byproducts. For the maatjes oil, a much lower value was found for alpha-tocopherol compared to the other oils. Storage stability results showed that the oils behave differently. Secondary oxidation products were measured for fresh oil, while for the maatjes and frozen byproducts' oil, tertiary oxidation products were detected. Over storage time, the maatjes and frozen byproducts' oils became more intense in odor, correlating positively at the end with sensory attributes of train-oil, acidic, marine and fishy. The best correlation between sensory and chemical analyses was found for FFA and fishy off-odor (r = 0.781).

Seasonal changes in crude and lipid composition of herring fillets, byproducts, and respective produced oils.

Crude and fatty acid composition analyses were performed on fillets, byproducts, and oil originating from herring (Clupea harengus) caught off the North Sea from June 1999 to January 2001. Monthly statistical differences were found in the fat content, the range of variation being larger in fillets than in byproducts. The most consistent change observed in fillets was an increase of unsaturation from May to September reflected in a reduced percentage of monounsaturated fatty acids, whereas for byproducts and oil this trend was not so well defined. The results indicated that the lowest values of the total amount of polyunsaturated fatty acids (PUFAs) in the oil were found from January to March (approximately 14%), coinciding with the postspawning and starvation period. In contrast, the highest values were found from June to August (approximately 23%). Thus, the herring byproducts are all year an adequate raw material for fish oil production; however, during the summer they are richer in PUFAs.

Composition and stability of herring oil recovered from sorted byproducts as compared to oil from mixed byproducts.

Herring oils produced from three different types of byproducts, only heads, mixed, and headless byproducts, were compared. Heads byproducts and its oil presented the highest oxidation levels and the lowest alpha-tocopherol content. Heads contained the lowest polyunsaturated fatty acids content and the highest amount of saturated fatty acids. No significant differences were found between the fatty acid composition of the mixed and the headless either in byproducts or in its oil. The oil was stored at two different temperatures (20 and 50 degrees C). Testing general linear models showed that oxidation was related to the peroxide value with a positive significant effect of the temperature, while the free fatty acids' model was more complex, with significant contribution of all of the effects studied. Fluorescence measurement was the one that correlated best with the oxidation progress.