Bio-Fortified Pork Cracklings with UVB LED Tailored Content of Vitamin D3.

Since few foods are naturally rich in vitamin D, novel food products with a high content of vitamin D are needed to decrease the prevalence of vitamin D deficiency. Pork cracklings are Danish snacks with high contents of protein and fat. They are consumed mostly during wintertime when sun exposure cannot fulfil human needs for vitamin D3. Pork cracklings were produced in an industrially friendly manner from UVB LED illuminated pork rind, using a combination of sous vide (85 °C, 60 min) and roasting in the oven (200 °C, 20 min). Thermal processing resulted in a significant loss of vitamin D3 (>90%). Thus, the process was optimized by the UVB exposure of pork cracklings, i.e., after thermal processing. The produced pork cracklings had a vitamin D3 level of ~10 µg/100 g, with a possibility of tailoring its final content. Furthermore, the fat content at 15−20% was a reduction of 50% compared to marketed products in 2021. No significant difference was found in the content of vitamin D3 during 31 days of storage in the air. A consumer preference test (n = 53) indicated that >80% of participants liked the product and saw its potential as a new food source of vitamin D3.

Quantification of vitamin D3 and 25-hydroxyvitamin D3 in food - The impact of eluent additives and labelled internal standards on matrix effects in LC-MS/MS analysis.

Deuterated vitamin D standards are used commonly as internal standards in LC-MS/MS analysis of vitamin D3 and 25-hydroxyvitamin D3 in food. However, the use of various eluent additives, such as methylamine, formic acid and ammonium formate, also contributes to matrix effects and the performance of analysis by affecting accuracy and robustness. For the first time, continuous post-column infusion experiments of isotopically labelled vitamin D3-[d6] were performed to evaluate ion-suppression in a wide variety of food (salmon, cheese, pork fat, pork meat, and egg yolk). Furthermore, results collected using five analytical methods, employing DAD/UV and MS/MS-detectors, were evaluated with in-house and standardised reference materials. The matrix effect was significant when analysing vitamin D3 in most food matrices using the deuterium labelled internal standard. Even though the use of the 13C5-labelled internal standard reduced matrix effects, a standardised method is needed to agree on the true value of vitamin D in food.

Vitamin K (phylloquinone and menaquinones) in foods - Optimisation of extraction, clean-up and LC-ESI-MS/MS method for quantification.

Growing evidence of vitamin K's importance in human health beyond blood coagulation and bone health necessitates its further research. A method involving extraction, lipase treatment, clean-up, and detection and quantification by LC-ESI-MS/MS of phylloquinone (PK), menaquinone-4 (MK-4), menaquinone-7 (MK-7) and menaquinone-9 (MK-9) was developed, and single-laboratory validated. The matrices included in the validation were hazelnut, cheese, broccoli, and pork. The LC-method runtime was 9 min. The LOQ for PK, MK-4 and MK-7 was 0.5 µg/100 g food, while for MK-9 it was 2.5 µg/100 g food. The intra- and inter-day precision was <15% for endogenous and spiked levels, except for low content at 4 times the LOQ. Trueness was assessed to be in the range 94-125% for spiking at levels approximately 4 and 10 times LOQ. It is further shown that deuterium labelled MK-7 can be used as an internal standard for MK-9.

Collaborative study: Quantification of total folate in food using an efficient single-enzyme extraction combined with LC-MS/MS.

Quantification of the specific folate vitamers to estimate total folate in foods is not standardized. A collaborative study, including eight European laboratories, was conducted in order to determine the repeatability and reproducibility of the method for folate quantification in foods using the plant-origin γ-glutamyl hydrolase as part of the extraction procedure. The seven food samples analyzed represent the food groups; fruits, vegetables, dairy products, legumes, offal, fish, and fortified infant formula. The homogenization step was included, and six folate vitamers were analyzed using LC-MS/MS. Total folate content, expressed as folic acid equivalent, was 17-490 µg/100 g in all samples. Horwitz ratio values were within the acceptable range (0.60-1.94), except for fish. The results for fortified infant formula, a certified reference material (NIST 1869), confirmed the trueness of the method. The collaborative study is part of a standardization project within the Nordic Committee on Food Analysis (NMKL).