size-exclusion chromatography comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-11-08. Numbers and descriptions here follow the published literature rather than marketing material.
Degree of hydrolysis is commonly estimated by titrating liberated carboxyl groups, measuring soluble nitrogen in trichloroacetic acid, or using o-phthaldialdehyde assays. Molecular weight distribution is often examined by size-exclusion chromatography, sodium dodecyl sulfate polyacrylamide gel electrophoresis, or mass spectrometry. These methods answer different questions: titration estimates bond cleavage, while chromatography describes peptide size ranges. Because no single reference method is universally applied, values reported by different laboratories may not be directly comparable. Method details such as calibration standards and sample preparation strongly influence results.
Routine quality control for hydrolysate powders includes total nitrogen or protein content by Kjeldahl or Dumas combustion, moisture by oven or Karl Fischer titration, ash, and mineral profiles. Microbiological tests typically cover total aerobic counts, yeasts, molds, and specified pathogens according to regional food safety rules. Amino acid analysis can quantify free amino acids and peptide-bound residues after hydrolysis. For products intended for special populations, additional tests may target residual lactose, fat, or specific allergenic proteins. Specifications are set by the manufacturer and may exceed general food-grade requirements.
Hydrolysate powders are hygroscopic and can absorb moisture during storage, which may promote caking, browning, and loss of solubility. Cool, dry conditions and sealed packaging slow these changes, while high humidity and warm temperatures accelerate Maillard reactions between peptides and residual sugars. Liquid hydrolysates are more perishable and often require refrigeration or preservatives. Shelf-life studies usually monitor moisture, color, solubility, free amino groups, and microbial load over time. Stability depends on residual lactose, water activity, packaging barrier properties, and the initial peptide profile.
Whey protein hydrolysate is a dairy ingredient made by breaking peptide bonds in whey proteins. Enzymes such as proteases, or in some processes acid or heat, cleave the protein chains into shorter peptides and free amino acids. The starting material may be sweet whey, acid whey, whey protein concentrate, or whey protein isolate. Because raw materials and reaction conditions differ, the final mixture is not a single uniform substance. Its peptide profile, mineral content, and residual lactose depend on the source and the processing steps used.
Production typically begins with pasteurization and concentration of whey. A protease is added under controlled temperature and pH, and the reaction is stopped by heat or pH change when the target extent of cleavage is reached. Ultrafiltration or diafiltration may remove enzymes, salts, and small molecules. The liquid is then spray dried into a powder. Process parameters shape bitterness, solubility, and peptide size. Established control points include enzyme type, reaction time, and inactivation conditions. How these variables interact across large-scale batches remains an area of active process development.
Hydrolysates usually contain 70% to 90% protein on a dry basis, with variable ash, fat, and carbohydrate. Solubility in water is generally high over a broad pH range, though bitter notes can appear from exposed hydrophobic peptides. The powder tends to absorb moisture and may brown during prolonged warm storage. Applications span sports nutrition, clinical nutrition, infant formulas, and flavor systems. Regulatory status and labeling rules differ by country. A key open question is whether a given peptide profile reliably predicts functional or sensory behavior across different food matrices.
| Property | Value | Notes |
|---|---|---|
| Moisture content | Typically below 6% | Higher moisture increases caking, browning, and microbial risk. |
| Water activity | Often below 0.6 | Low water activity limits microbial growth in dry powders. |
| Typical storage temperature | 15–25 °C | Keep sealed, dry, and away from strong odors and direct light. |
| Protein quantification | Kjeldahl or Dumas combustion | Measures total nitrogen; a conversion factor estimates protein. |
| Peptide size analysis | Size-exclusion chromatography or mass spectrometry | Results depend on method, calibration, and sample preparation. |
Quality control checks identity, composition, and contaminants. Moisture, ash, fat, and carbohydrate are measured by standard methods, and microbiological limits are set for total counts, coliforms, and specific pathogens. Heavy metals and pesticide residues may be monitored depending on market requirements. Adulteration with intact whey protein or individual amino acids is possible, so peptide fingerprints and free amino acid profiles can help verify authenticity. Regulatory frameworks vary: some countries treat hydrolyzed whey as a conventional dairy ingredient, while infant formula uses face additional compositional rules. Which marker peptides best confirm source and processing remains an open analytical question.
Storage stability depends on moisture, temperature, and packaging. Dry powders with low water activity resist microbial growth, but they can still absorb water, develop off-colors through Maillard reactions, or oxidize residual lipids. Sealed containers kept in a cool, dry place are standard. Stability studies typically monitor moisture, solubility, color, peptide size, and microbial counts over months. Established practice favors low humidity and moderate temperatures. How brief excursions above recommended conditions affect peptide profiles and sensory qualities is less predictable and may depend on the specific product matrix.
Regulatory treatment of whey protein hydrolysate depends on the country and intended use. In many jurisdictions it is regulated as a food ingredient or food for special dietary use, not as a drug. Labeling rules govern allergen statements, protein content claims, and ingredient names. Some markets have specific rules for infant formula ingredients, where hydrolysates may be used for particular dietary purposes. Regulations generally focus on safety, truthful labeling, and manufacturing standards rather than on therapeutic effects. Scientific questions about specific peptide activities remain an active area of research rather than a settled regulatory category.
Whey protein hydrolysate powders are hygroscopic and can absorb moisture from air. Moisture uptake may lead to caking, reduced flowability, and gradual peptide degradation. Manufacturers typically specify cool, dry storage and sealed packaging to limit these changes. Water activity, rather than water content alone, is often monitored because it better predicts microbial and chemical stability. High temperatures can accelerate Maillard reactions between peptides and residual sugars, altering color and flavor. Exact shelf lives depend on formulation, packaging, and initial moisture, so they are usually determined by product-specific stability testing.
Analytical testing for whey protein hydrolysate focuses on peptide size distribution, degree of hydrolysis, protein content, moisture, ash, and microbiological quality. Size-exclusion chromatography and mass spectrometry can characterize peptide profiles, while Kjeldahl or combustion methods estimate total nitrogen and protein. Amino acid analysis quantifies free and total amino acids. Because peptide mixtures are complex, no single method captures every property, and results can vary between laboratories. Standardized methods and reference materials help improve comparability, but full sequence-level characterization remains uncommon in routine quality control.
4 August – Tom Sawyer, Baron Sawyer, 82, British trade unionist and politician, member of the House of Lords (since 1998). (death announced on this date) 12 August – Hefin David, 47, Welsh politician, Member of the Senedd (2016–2025). Sir George Reid, 86, Scottish politician, presiding officer of the Scottish Parliament (2003–2007), kidney cancer. 20 August – Dame Annette Brooke, 78, British politician, MP (2001–2015). 21 August – Swraj Paul, Baron Paul, 94, Indian-born British industrialist and politician, member of the House of Lords (since 1996). 22 August – Martin Smyth, 94, Northern Irish politician, MLA (1982–1986) and MP (1982–2005). (death announced on this date) 26 August – David Warburton, 59, British politician, MP (2015–2023). 30 August – Tim Boswell, Baron Boswell of Aynho, 82, British politician, MP (1987–2010) and member of the House of Lords (2010–2025). 10 September – Alan Howarth, Baron Howarth of Newport, 81, British politician, MP (1983–2005) and member of the House of Lords (since 2005). 17 September – Barry Seal, 87, British politician, MEP (1979–1999), acute myeloid leukaemia. 18 September – Charles Guthrie, Baron Guthrie of Craigiebank, 86, British field marshal, assistant chief (1987–1989) and chief (1994–1997) of the general staff, chief of the defence staff (1997–2001), ruptured cerebral aneurysm. 23 September – Iain Coleman, 67, British politician, MP (1997–2005). (death announced on this date) 26 September – Menzies Campbell, 84, British politician, MP (1987–2015).
In July 2015, Allergan agreed to sell its generic drug business (Actavis Generics) to Teva for $40.5 billion ($33.75 billion in cash and $6.75 billion worth of shares). As a result, Teva dropped its pursuit of Mylan. In order for the deal to gain regulatory approval, Teva sold off a number of assets, including a portfolio of five generic drugs to Sagent Pharmaceuticals for $40 million, as well as a further eight medicines to Dr. Reddy's in a $350 million deal. Teva also sold a further 15 marketed generics, as well as three others that were close to market, for $586 million to Impax Laboratories. In July, Teva sold off a further 42 products to Australian generics company, Mayne Pharma, for $652 million; the deal moved Mayne up 50 spots, into the top-25 companies of US generic companies. As part of the deal Teva will seek to raise $20 to $25 billion through a bond sale. After completing the $39 billion acquisition of Actavis Generics, Teva announced another, smaller, deal with Allergan, agreeing to acquire its generic distribution business Anda for $500 million.
=== Enzymatic labeling === In enzymatic labeling, a DNA construct is first formed, using a gene and the DNA of a fluorescent protein. After transcription, a hybrid RNA + fluorescent is formed. The object of interest is attached to an enzyme that can recognize this hybrid DNA. Usually fluorescein is used as the fluorophore.
Sources: en.wikipedia.org
==== Small RNA ==== At first, regulatory RNA was thought to be a eukaryotic phenomenon, a part of the explanation for why so much more transcription in higher organisms was seen than had been predicted. But as soon as researchers began to look for possible RNA regulators in bacteria, they turned up there as well, termed as small RNA (sRNA). Currently, the ubiquitous nature of systems of RNA regulation of genes has been discussed as support for the RNA World theory. There are indications that the enterobacterial sRNAs are involved in various cellular processes and seem to have significant role in stress responses such as membrane stress, starvation stress, phosphosugar stress and DNA damage. Also, it has been suggested that sRNAs have been evolved to have important role in stress responses because of their kinetic properties that allow for rapid response and stabilisation of the physiological state. Bacterial small RNAs generally act via antisense pairing with mRNA to down-regulate its translation, either by affecting stability or affecting cis-binding ability. Riboswitches have also been discovered. They are cis-acting regulatory RNA sequences acting allosterically. They change shape when they bind metabolites so that they gain or lose the ability to bind chromatin to regulate expression of genes.
== Bibliography == Shapiro, Fred R.; Epstein, Joseph (2006). The Yale Book of Quotations. Yale University Press. ISBN 978-0-300-10798-2. Willmott, H. P. (2003). World War I. Dorling Kindersley. ISBN 978-0-7894-9627-0. OCLC 52541937.
== Health-related sustainable development goals == In September 2015, the UN General Assembly established Sustainable Development Goals (SDGs). The SDGs specify 17 universal goals, 169 targets, and 230 indicators. A paper published in The Lancet analyzed 33 health-related SDG indicators based on the Global Burden of Disease Study 2015 (GBD 2015). Of 188 nations, Thailand ranked 112 (1=best; 188=worst). Rankings of other ASEAN nations were: Singapore, 2; Brunei, 21; Malaysia, 46; Indonesia, 91; Vietnam, 94; Philippines, 127; Cambodia, 130; Myanmar, 135; and Laos, 136.
==== Electrical conductivity ==== Completely de-gassed ultrapure water has a conductivity of 1.2 × 10−4 S/m, whereas on equilibration to the atmosphere it is 7.5 × 10−5 S/m due to dissolved CO2 in it. The highest grades of ultrapure water should not be stored in glass or plastic containers because these container materials leach (release) contaminants at very low concentrations. Storage vessels made of silica are used for less-demanding applications and vessels of ultrapure tin are used for the highest-purity applications. Although electrical conductivity only indicates the presence of ions, the majority of common contaminants found naturally in water ionize to some degree. This ionization is a good measure of the efficacy of a filtration system, and more expensive systems incorporate conductivity-based alarms to indicate when filters should be refreshed or replaced. For comparison, seawater has a conductivity of perhaps 5 S/m (53 mS/cm is quoted), while normal un-purified tap water may have conductivity of 5 × 10−3 S/m (50 μS/cm) (to within an order of magnitude), which is still about 2 or 3 orders of magnitude higher than the output from a well-functioning demineralizing or distillation mechanism, so low levels of contamination or declining performance are easily detected.
Sources: en.wikipedia.org
== Etymology == A dialectal English name for bats is "flittermouse", which matches their name in other Germanic languages (for example, German Fledermaus and Swedish fladdermus), related to the fluttering of wings. Middle English had bakke, most likely cognate with Old Swedish natbakka ('night-bat'), which may have undergone a shift from -k- to -t- (to Modern English bat) influenced by Latin blatta, 'moth, nocturnal insect'. The word bat was probably first used in the early 1570s. The order name Chiroptera derives from the Ancient Greek χείρ (kheír), meaning "hand", and πτερόν (pterón), meaning "wing".
Societal views, influenced by tradition, a lack of knowledge on anatomy, or sexism, can significantly impact a person's decision to alter their own or another person's genitalia. Women may want to alter their genitalia (vagina or vulva) because they believe that its appearance, such as the length of the labia minora covering the vaginal opening, is not normal, or because they desire a smaller vaginal opening or tighter vagina. Women may want to remain youthful in appearance and sexual function. These views are often influenced by the media, including pornography, and women can have low self-esteem as a result. They may be embarrassed to be naked in front of a sexual partner and may insist on having sex with the lights off. When modification surgery is performed purely for cosmetic reasons, it is often viewed poorly, and some doctors have compared such surgeries to female genital mutilation (FGM). Female genital mutilation, also known as female circumcision or female genital cutting, is genital modification with no health benefits. The most severe form is Type III FGM, which is infibulation and involves removing all or part of the labia and the vagina being closed up. A small hole is left for the passage of urine and menstrual blood, and the vagina is opened up for sexual intercourse and childbirth.
Instead, they stretch to compensate for dead cells which reduces the overall cell density of the endothelium, which affects fluid regulation. If the endothelium can no longer maintain a proper fluid balance, stromal swelling due to excess fluids and subsequent loss of transparency will occur and this may cause corneal edema and interference with the transparency of the cornea and thus impairing the image formed. Iris pigment cells deposited on the corneal endothelium can sometimes be washed into a distinct vertical pattern by the aqueous currents - this is known as Krukenberg's Spindle.
=== Pyruvic acid production by glycolysis === In the last step of glycolysis, phosphoenolpyruvate (PEP) is converted to pyruvate by pyruvate kinase. This reaction is strongly exergonic and irreversible; in gluconeogenesis, it takes two enzymes, pyruvate carboxylase and PEP carboxykinase, to catalyze the reverse transformation of pyruvate to PEP.
Much of the Gulf states' food is imported – for example, over 90 per cent in Qatar. These factors have led to fears of food insecurity not only in Gulf states, but around the world. As of 28 March, analysts fear that another hard oil crisis is unfolding that is expected to be very decisive to the global economy. Oil prices increased on September 13 due to market stability after recent declines. Investors are awaiting potential U.S.-Iran talks at the UN General Assembly. Analysts believe the price rise may result from traders adjusting their positions rather than a change in market trends.
Sources: en.wikipedia.org
Peptide size is commonly estimated by size-exclusion chromatography, gel electrophoresis, or mass spectrometry. These techniques separate or identify molecules according to mass or hydrodynamic volume. Results depend on calibration and method conditions, so they are best compared within the same analytical protocol.
Clumping usually reflects moisture uptake by hygroscopic peptides and residual lactose. High humidity, temperature fluctuations, and damaged packaging can worsen caking. Sealed containers with desiccant and controlled storage reduce the problem.
No universal reference method exists for all hydrolysates, although several established assays are used. Different methods measure different chemical features and can produce different numerical values. For this reason, specifications should state the assay and laboratory conditions.
Hydrolysis extent indicates the share of peptide bonds that have been cleaved. It is often estimated from free amino groups and is reported as a percentage. A higher value means smaller peptides and more free amino acids, but it does not by itself define product quality.