Dairy Processing: The Soft Spreadable Cheese Xygalo Siteias

The aim of cheese manufacturers is to produce high quality and safe products. Along the food chain of “milk to cheese and food products”, milk is collected, transferred, and managed in a standardized manner; processing results in safe, ready-to-eat products, of high nutritional quality. Soft, acid cheeses are prepared in various regions of Greece, mainly from ewe milk, goat milk, or their mixtures. They are produced from the rennet and/or acid coagulation of thermally-treated, full-fat milk undergoing acidification/curdling and ripening. Xygalo Siteias is a Greek soft cheese, produced in the area of Siteia, Crete, where it was recognized as PDO in 2011. It is close—more in texture and less in taste—with other cream cheeses PDO of Greece, such as Pichtogalo of Chania, and Katiki Domokou, still it differs in the preparation technique as well as in its physicochemical, biochemical, microbiological, and organoleptic characteristics. In this review, we focus on the processing and characteristics of Xygalo Siteias, mentioning perspectives for the further microbiological characterization of the product, the determination of its shelf-life in combination with new packaging-materials, as well as the attention it deserves as a food important for breeders, the local economy, and consumers, since it is associated with the Cretan-Mediterranean diet type.

Recovery of Gold in Au/Cu/Mg System from SH/Fe3O4@SiO2 as a Magnetically Separable and Reusable Adsorbent

The recovery of Au(III) in the Au/Cu/Mg system from mercapto-silica hybrid coated magnetite (SH/Fe3O4@SiO2) adsorbent has been investigated. This adsorbent characterized using FT-IR to determine functional groups, crystallinity study using XRD, surface morphology using SEM, material compositions with XPS, surface area using nitrogen adsorption, and TGA to study thermal stability. Adsorption of metal ions carried out with batch system for 30 minutes at a pH of 3. In the Au/Cu/Mg multi-metal system, Au(III) ions were easily desorbed (approximately 85%) by SH/Fe3O4@SiO2 adsorbent based on HSAB (Hard Soft Acid Base) theory that Au(III) ion is a softer metal than Cu(II) and Mg(II) where Au(III)>Cu(II)>Mg(II). The recovery of Au(III) ions was easily desorbed using thiourea 7% in 0,1 M HCl solution with the percentage of 79%. The process of SH/Fe3O4@SiO2 adsorbent separation after adsorption and recovery was very easy. The adsorbent could perfectly separate in 5 minutes using an external magnet. The SH/Fe3O4@SiO2 adsorbent can be reused on the adsorption-desorption process of Au(III) in the Au/Cu/Mg system approximately four times of cycle reactions.

Effects of nitrogen depletion on the biosorption capacities of Neochloris minuta and Neochloris alveolaris for five heavy metals

Neochloris minuta and Neochloris alveolaris grown in nitrogen-rich (+ N) and nitrogen-depleted (-N) media were tested for their heavy metal maximum biosorption capacities (qmax) and adsorption percent efficiencies (R%). By removing nitrogen from the growth media, both algal species showed an increase in their lipid content and a decrease in their protein content. Langmuir and Freundlich adsorption isotherms were used to determine the qmax and adsorption efficiencies of the + N and −N algae in the recovery of Pb2+, Cd2+, Zn2+, Cu2+, and Ni2+. When comparing the two types of algae, N. alveolaris showed the highest adsorption capacities for all five metals either in + N or -N media. The maximum adsorption efficiency percentage of the lowest concentration metal ions for N. alveolaris was 87.10% for Pb2+, 64.98% for Cd2+, 59.50% for Zn2+, 60.08% for Cu2+, and 50.61% for Ni2+. In both algae, nitrogen depletion (-N) caused an increase in the qmax values for Zn2+ and Cu2+. Additionally, the qmax of N. minuta for Cd2+, Zn2+, Cu2+ and Ni2+ increased by the nitrogen depletion demonstrating that the treatment can be applied to improve the biosorption capacity of a particular alga for multiple heavy metals. The biosorption capacity for these algae for heavy metals was also discussed in terms of their biomass compositions and the type of hard or soft metal acid based on the Pearson theory of Hard and Soft, Acid and Bases (HSAB).

Application of hard and soft acid base theory to uncover Lewis bases’ destructiveness to UiO-66 type metal organic frameworks in aqueous solutions

Lewis bases (L-bases) in wastewater, such as F- and PO43-, are destructive to the stability of MOFs which have attracted increasing attentions in wastewater treatment field as adsorbents and catalysts....

A Tuned Lewis Acidic Catalyst Guided by Hard-soft Acid-base Theory to Promote N2 Electroreduction

Electrocatalytic N2 reduction reaction (NRR) to ammonia (NH3) driven by intermittent renewable electricity under ambient conditions offers an alternative to the energy-intensive Haber−Bosch process. However, as a distinct core of...

Identifying Undergraduate Students’ Misconceptions in Understanding Acid Base Materials

Students’ misconceptions have become phenomenon in teaching and learning, especially in chemistry which is considered as difficult subject. The objective of this study is to identify undergraduate student’s misconception profiles related to acid-base concepts in inorganic chemistry. This test was conducted with 15 item three tier multiple choices test. Data were identified descriptively and qualitatively. This test instruments are judged as valid with CVR score of 0,99 and mean of 1,73. Meanwhile, the reliability for this instrument varies for each tier combination; for tier one only, r11 was given reliability score for 0,93; for combination tier one and tier two, r11 score was 0,90, and for combination of all tiers, r11 score was 0,81. The test conducted revealed that average percentage of misconception in this test is 33.31% for all items. The highest misconception profile is 60,61% in item no.6 hard soft acid base concept. This includes 15,15% misconception false positive, 9,09% misconception false negative, and 36.36% specific misconception.