Enhancing Red Yeast Biomass Yield and Lipid Biosynthesis by Using Waste Nitrogen Source by Glucose Fed-Batch at Low Temperature.

This work reports the effect of simple feeding strategies and temperature to obtain high-cell-density cultures of Rhodotorula glutinis var. rubescens LOCKR13 maximizing the de novo lipid productivity using deproteinated potato wastewater (DPW) as a basic medium. Feeding DPW with glucose enables a high yield of Rhodotorula glutinis var. rubescens LOCKR13 biomass (52 g d.w. L−1) to be obtained. The highest values of lipid accumulation (34.15%, w/w), production (14.68 g L−1) and yield coefficients (YL/S: 0.242 g g−1), and volumetric productivity (PL: 0.1 g L−1 h−1) were reached by the strain in the two-stage fed-batch process at 20 °C. The lipid of yeast biomass was rich in oleic acid (Δ9C18:1) and palmitic acid (C16:0), and the lower temperature of incubation significantly increased the MUFA (especially oleic acid) content. For the first time, a unique set of thermal analyses of the microbial oil was performed. The isotherms of the oxidation kinetics (PDSC) showed that lipids extracted from the biomass of red yeast had high oxidative stability. This feature of the yeast oil can be useful for long-shelf-life food products and can be promising for the production of biodiesel.

The Effect of Composition, Pre-Treatment on the Mechanical and Acoustic Properties of Apple Gels and Freeze-Dried Materials.

This study aimed to determine the effect of the addition of apple juice concentrate (AJC) on the properties of agar gel and dried materials. Agar gels with the addition of apple juice concentrate in the range of 5-20% were prepared with or without the addition of maltodextrin. The gels were also soaked in the solution of AJC. The water content, water activity, densities, some mechanical and acoustic descriptors of gels, and the freeze-dried gels were analysed. The porosity and shrinkage of dried products were also investigated. The addition of AJC significantly changed mechanical and acoustic properties of gels. The hardness of gels decreased with a higher addition of concentrate. Dried samples with a lower concentration of sugars (the lower addition of AJC) were characterised by lower shrinkage and higher porosity, as well as crispness and glass transition temperature. The investigated mechanical and acoustic properties of dried gels showed the addition of apple concentrate at the level of 5% to agar solution was optimal.

Assessment of the Starch-Amylolytic Complex of Rye Flours by Traditional Methods and Modern One.

The properties of the starch-amylolytic complex of commercial low-extract rye flour were determined based on the traditional method, such as falling number and amylograph test as well as differential scanning calorimetry (DSC). The starch, pentosans and protein had a significant effect on the thermal properties of the tested rye flours. Based on the falling number, it was revealed that rye flours were characterized by medium and low alpha-amylase activity. The falling number and amylograph test are not sufficient methods to determine the suitability of currently produced rye flours for bread making. The gelatinization process of the rye flour starch could be evaluated by the DSC test, which, together with the falling number and amylograph test, may allow a better way to evaluate the usefulness of rye flours for bread making. Many significant correlations between parameters determined by DSC endotherm and quality parameters of rye bread, such as volume and crumb hardness, were reported. Breads made from flour with higher enthalpy in DSC were characterized by higher volume and softer crumb.

Quality assessment of cold-pressed strawberry, raspberry and blackberry seed oils intended for cosmetic purposes.

BACKGROUND: Cold-pressed berry seed oils are used for consumption and other applications including skin and hair care. They are natural products which gain the attention of customers. In this study, strawberry, raspberry and blackberry seed oils used for cosmetic purposes, purchased from three different European producers, were analyzed. The aim of the study was to assess the quality and oxidative stability of the berry fruit oils, thus they were analyzed after purchase and after 4 and 8 weeks of storage at room temperature. METHODS: Acid and peroxide values were determined in the tested oils, as was oxidative stability, which was measured using pressure differential scanning calorimetry (PDSC). Additionally, fatty acid profiles and thei. RESULTS: nd. Cold-pressed berry seed oils are used for consumption and other applications including skin and hair care. They are natural products which gain the attention of customers. In this study, strawberry, raspberry and blackberry seed oils used for cosmetic purposes, purchased from three different European producers, were analyzed. The aim of the study was to assess the quality and oxidative stability of the berry fruit oils, thus they were analyzed after purchase and after 4 and 8 weeks of storage at room temperature. Materials and methods. Acid and peroxide values were determined in the tested oils, as was oxidative stability, which was measured using pressure differential scanning calorimetry (PDSC). Additionally, fatty acid profiles and their distribution at sn-1,3 and sn-2 positions of triacylglycerols were characterized. Results, principal. Most of the fatty acids of the tested berry seed oils are polyunsaturated fatty acids (67.04-74.95%). The results show the low quality of the tested oils in terms of oxidative stability (high peroxide values: 21.9-249.6 mEq O2/kg oil). CONCLUSIONS: Based on this study, it is necessary to evaluate the effects of these products on the body. Moreover, standards clarifying the oxidation of cosmetic oils should be set internationally.

Reformulation of spray-dried apple concentrate and honey for the enhancement of drying process performance and the physicochemical properties of powders.

BACKGROUND: Apple concentrate and honey were spray-dried with traditional carriers (maltodextrin, Nutriose®, Kleptose®) and with skimmed milk powder as a carrier substitute offering added value for the final product. RESULTS: Skimmed milk powder, although having the lowest glass transition temperature, was the best carrier in terms of the highest powder recovery (higher than 80% was achieved) and with powder physical properties comparable to those obtained with other carriers. Thus, skimmed milk powder was used to produce honey powder of reduced carrier content (to 25% solids). The physical properties of the powders obtained and lower powder recovery indicated more problematic drying of AC. Powders produced with skimmed milk were characterized by enhanced nutritional value compared with variants with traditional carriers. CONCLUSION: Thus, skimmed milk is proposed as a natural carrier for spray-drying, offering high processing yield, the possibility to reduce carrier content in honey powder, and to create products of nutritional added value. © 2020 Society of Chemical Industry.

The Synthesis Followed by Spectral and Calorimetric Evaluation of Stability of Human Milk Fat Substitutes Obtained from Thistle Milk and Lard.

The central point of current investigations was the first time ever synthesis of modern substitutes of human milk fat followed by versatile evaluation of their oxidative properties. The enzymatic interesterification conducted at 70°C for 2, 4, and 6 hours, respectively, with milk thistle oil and lard blend as starting reactants was catalyzed by 1,3-specific lipase Lipozyme RM IM, obtained from Rhizomucor miehei. Pressure Differential Scanning Calorimetry (PDSC) and Fourier Transform Infrared Spectroscopy (FT-IR) were applied to evaluate quality of products formed. Although PDSC curves showed lower oxidative stability of newly synthesized fats as compared to both starting materials separately, they can be considered adequate substitutes of human fat milk fat, as distribution of fatty acids in triacylglycerol molecules of substitutes obtained is much alike human milk fat itself, as resulted from analysis of GC data collected. Obvious changes in chemical structure of fats occurring during interesterification resulted in specific alterations in IR spectra of processed materials. Spectral data accompanied by PLS technique were successfully used for accurate determination of oxidative stability of new fats through indirect procedure, i.e., IR-PDSC-reference analysis of induction time. Additionally IR data exclusively, i.e., without any reference data, occurred powerfully in discrimination of human fat milk substitutes obtained.

Effect of hydrothermal modifications on properties and digestibility of grass pea starch.

This study aimed to investigate functional and thermal properties and digestibility of grass pea starch, and provide information on the effect of hydrothermal modifications - annealing (ANN) and heat-moisture treatment (HMT) on the physico-chemical characteristics of the starch and digestibility, especially after processing (cooking, storage after cooking and freezing). After heat treatment, especially after cooking and storage at a temperature of -18 °C, the total content of slowly digestible starch and resistant starch in grass pea starch was high, which may indicate its great tendency for retrogradation. The HMT and ANN modifications of grass pea starch caused changes in its crystalline structure and increased integrity of its granules, which in turn resulted in a lower swelling power and amylose leaching, however this effect was more pronounced upon HMT which contributed to starch polymorphic type transformation from C to A. Despite greater resistance of granules of modified starches to swelling during cooking their suspensions, after cooking these starches were characterized by a higher predicted glycemic index than the non-modified ones. A similar content of resistant starch determined in modified and non-modified gelatinized starches stored at lowered temperatures indicates that starch modifications, HMT in particular, cause no changes in its susceptibility to retrogradation.

Oxidative stability and triacylglycerols structure of lipid fraction from cookies for infants.

The aim of this research was to analyse the quality of the lipid fraction extracted from commercially available cookies intended for infants. The composition, fatty acid distribution and oxidative stability of fats, interpreted as the resistance of fats against autooxidation, were studied. In addition, the kinetic parameters of the oxidation process, such as activation energies (E(a)), pre-exponential factors (Z) and reaction rate constants (k) for fat oxidation under the differential scanning calorimetry tests conditions were calculated using the Ozawa-Flynn-Wall method and the Arrhenius equation. The distribution of fatty acids in the tested cookies is similar to that present in most of infant formulas, but differs significantly from that in human milk. Based on the results obtained, high oxidative stability of tested fats can be observed. The E(a) values ranged from 86.22 to 116.13 kJ/mol; Z from 1.95 × 10(9) to 1.05 × 10(13); and k values ranged from 5.70 × 10(- 4) min(- 1) at 100°C to 2.12 × 10(- 1) min(- 1) at 170°C.