Quantification of free sugars, fructan, pungency and sweetness indices in onion populations by FT-MIR spectroscopy.

BACKGROUND: To facilitate faster phenotyping of onions (Allium cepa L.), Fourier-transform mid infrared (FT-MIR) spectroscopy with partial least squares (PLS) regression modelling was evaluated for the determination of pungency (pyruvate), sweetness (free sugars) and fructan in juice samples (n = 605) expressed from bulbs from breeding populations. RESULTS: Fourier-transform infrared (FTIR) spectra (range 1700-900 cm-1 ) were obtained from droplets (30 µL) of unprocessed juice. Goodness-of-fit (r2 ) and prediction errors (standard error of cross validation) for optimal PLS models were: soluble solids (0.997, 0.1 °Brix), pyruvate [0.825, 0.8 µmol g-1 fresh weight (FW)], fructan (0.98, 1.9 mg g-1 FW), glucose (0.941, 1.1 mg g-1 FW), fructose (0.967, 1.0 mg g-1 FW) and sucrose (0.919, 1.7 mg g-1 FW). FTIR models for industry sweetness indices based on glucose or sucrose equivalents were also developed. Because of its very low concentration (0.8-12 µmol g-1 FW) relative to other compounds, pyruvate was the weakest model developed. Fructan could be determined spectroscopically without the need for enzymatic digestion. CONCLUSIONS: All of the chemometric models developed are acceptable for screening purposes. Those for soluble solids, fructan and fructose are also suitable for routine analysis. FT-MIR can therefore be utilised for the simultaneous determination of pungency, sweetness and fructan in this crop. © 2018 Society of Chemical Industry.

A six year head-to-head comparison of osteopathic and allopathic applicants to a university-based, allopathic general surgery residency.

OBJECTIVE: The number of osteopathic physicians is increasing as is the number applying to allopathic general surgery residency programs. A lack of knowledge of osteopathic schooling leads to a potential applicant bias in favor of allopathic applicants, but the 2 groups have not been compared head to head. DESIGN: Applications over a 6-year period to an allopathic general surgery residency program were reviewed. Demographics, examination scores, employment, education, and research experience were catalogued into a database. Allopathic applicants were compared with osteopathic applicants utilizing statistical analysis. SETTING: A university teaching hospital. PARTICIPANTS: Allopathic and osteopathic applicants to an allopathic general surgery residency program. RESULTS: A total of 1290 applications were reviewed; 1155 allopathic and 135 osteopathic applications. Other than race, the 2 cohorts are similar in age, gender, and citizenship. The groups are not significantly different with regard to the number of letter of recommendations, volunteer activities, scholarly works, and advanced degrees. Graduates of both proceed directly to residency. A significantly higher percentage of allopathic graduates reported their United States medical licensing examination (USMLE) scores, yet when osteopaths released their USMLE transcript, they scored significantly higher on the USMLE Step 1 examination and required fewer attempts to pass. These differences do not apply to the USMLE Step 2 examination. CONCLUSIONS: No single screening tool exists for selecting a successful general surgery resident. We are seeing increased numbers of osteopathic applicants. Many criteria used to evaluate applicants do not apply to osteopathic applicants, but our comparison of common selection variables on the Electronic Residency Application Service (ERAS) application did not demonstrate an overall difference. While our analysis demonstrated a statistically higher USMLE Step 1 score by osteopathic applicants, they may only self-report favorable data.

Pectins from the albedo of immature lemon fruitlets have high water binding capacity.

The white part of citrus peel, the albedo, has a special role in water relations of both fruit and leaves from early on in fruit development. In times of drought, this tissue acts as a water reservoir for juice sacs, seeds and leaves. When water was injected into the albedo, free water was undetectable using magnetic resonance imaging. Microscopy showed tightly packed cells with little intercellular space, and thick cell walls. Cell wall material comprised 21% of the fresh albedo weight, and contained 26.1% galacturonic acid, the main constituent of pectin. From this, we postulated that pectin of the cell wall was responsible for the high water-binding capacity of the immature lemon albedo. Cell wall material was extracted using mild procedures that keep polymers intact, and four pectic fractions were recovered. Of these fractions, the SDS and chelator-soluble fractions showed viscosities ten and twenty times higher than laboratory-grade citrus pectin or the other albedo-derived pectins. The yield of these two pectins represented 28% of the cell walls and 62% of the galacturonic acid content of immature lemon albedo. We concluded that, from viscosity and abundance, these types of pectin account for the high water-binding capacity of this tissue. Compositional analyses showed that the two highly viscous pectic fractions differ in galacturonic acid content, degree of branching and length of side chains from the less viscous albedo-derived pectins. The most striking feature of these highly viscous pectins, however, was their high molecular weight distribution compared to the other pectic fractions.