Doan D Nguyen

A rapid and simple inductively coupled plasma atomic emission spectrometry (ICP OES) method was developed and validated for the determination of macroelements including calcium (Ca), phosphorus (P), potassium (K), sodium (Na), and magnesium (Mg) in Australian retail pasteurised milk. The milk samples were digested using the mixture of 70% HNO3 and 30% H2O2 (2 : 1, v/v) in an open-tube digester block at 120 degrees C for 4 h. The validated ICP OES method showed good linearity for all elements (R-2 > 0.9993). The method limits of quantification (LOQ) for Ca, P, K, Na, and Mg were 19.85, 8.97, 100.8, 41.92, and 11.56 mu gg(-1), respectively. Recoveries were in the range of 91.54-116.0%. Repeatability and interday reproducibility expressed as the relative standard deviation (% RSD) was below 5.0%. The contents of macroelements in 6 retail pasteurised milk samples were between 1099.32 and 1348.65 mu gg(-1) (Ca), 914.01 and 1091.21 mu gg(-1) (P), 1362.76 and 1549.74 mu gg(-1) (K), 288.89 and 323.22 mu gg(-1) (Na), and 97.62 and 110.57 mu gg(-1) (Mg). Principal component analysis (PCA) revealed that retail pasteurised milk samples were distinctly separated into four groups on the first two principal components (PCs). The difference in the macroelement content between milk brands might be affected by milk regions.

The fatty acid composition of Western Australian commercial pasteurised milk was profiled using gas chromatography-mass spectrometry (GC–MS). A total of 31 fatty acids (FA) were identified in the milk samples. The majority of FA were medium-chain fatty acids (MCFA) with 6–13 carbon atoms and long-chain fatty acids (LCFA) with 14–20 carbon atoms. The results of principal component analysis (PCA) showed significant differences in the levels of MCFA and LCFA in the different milk samples. The levels of MCFA and LCFA ranged from 10.09 % to 12.12% and 87.88% to 89.91% of total FA, respectively. C10:0 and C12:0 were the major components of MCFA comprising 3.46% and 4.22% of total FA, while C16:0 and C18:1 (cis 9-octadecenoic acid) represented the majority of LCFA with the levels of 26.18% and 23.34% of total FA, respectively. This study provides new insight into the FA composition of Western Australian pasteurised milk and differences in FA profiles which influence human health.

Empty carob pods, a by‐product of carob seed production, are abundant in D‐pinitol, dietary fibre and phenolics, offering diverse potential health benefits. However, they also contain high levels of sugars. This study evaluated the capacity of Saccharomyces cerevisiae in submerged fermentation of empty carob pods to enhance D‐pinitol to total carbohydrate ratio, and contents of dietary fibre, and phenolics. Empty carob pods were fermented at pH 5.0, 5.5, 6.0, 6.5, and 7.0 at 30 °C for 10, 20, 30 and 50 h. After 20 h of fermentation, the total carbohydrates decreased by 70% ( P < 0.001); the ratio of D‐pinitol to total carbohydrates increased by nearly fivefold ( P < 0.05); total phenolic and total flavonoid contents and antioxidant activity significantly increased ( P < 0.05), whereas condensed tannin content and α‐glucosidase inhibitory activity remained stable. Fermented carob pods may be potentially used as a functional food ingredient to help control blood glucose levels.

Hyacinth bean was used for developing a functional yogurt-like product with a high level of gamma aminobutyric acid (GABA). Germinated hyacinth bean extract was fermented with three different yogurt cultures to pH 4.5 and then stored at 4–6°C for 21 days. The variation in GABA and phytic acid levels during cold storage was evaluated. The type of culture and storage time significantly influenced GABA and phytic acid levels. Lactococcus lactis ssp. cremoris, Lc. lactis ssp. lactis and Streptococcus thermophilus produced a yogurt-like product with the highest level of GABA. In addition, the level of GABA and phytic acid significantly decreased during cold storage.

Consumers have shown increased interest in functional milk products that promote health and prevent disease.(Reference Nguyen, Busetti and Johnson1) Milk fat has an important nutritional role.(Reference Gómez-Cortés, Juarez and de la Fuente2) The purpose of this study (part of an Innovation Connections Grant with Bannister Downs Dairy) was to determine if quality or nutritional differences exist in milk processed in WA. Six different WA retail pasteurised whole milk products were provided by six dairy manufacturers and collected from two local supermarkets in March and September 2022. Milk composition was analysed using the Milkoscan FT1 (Foss, Hillerod, Denmark) for fat, protein, lactose and solids-non-fat (SNF) content. The separation and quantification of fatty acids (FAs) were performed using gas chromatography-mass spectrometry (GC-MS) (Agilent 7890 GC system fitted with a mass spectrometer detector (MSD) and a capillary column (30 m × 250 μm × 0.25 μm, DB-5 ms, Agilent). Whole milk colour measurements were measured using a BYK spectroguide handheld spectrophotometer to measure CIE L*, a*, b*. A discrimination test (Triangle test) was used to determine whether sensory differences existed between the different milk samples. Milkoscan protein, lactose and solids-non-fat (SNF) results were not significantly different between dairy manufacturers (p > 0.05) and one dairy manufacture's fat content (3.5%) was significantly higher than the others (p < 0.05). All dairy manufactures results matched their product nutritional panel. Fat content was 3.1–3.5%, protein content was 3.2–3.4%, lactose content was 4.6–4.8% and SFN content was 8.7–9.1%. Principal component analysis (PCA) showed significant difference in concentration of medium-chain fatty acids (MCFA) and long-chain fatty acids (LCFA) between WA milk samples. The level of MCFA ranged from 10.1% to 12.1% of the total identified fatty acids (FAs) determined and were predominantly C12:0 and C10:0. The level of LCFA ranged from 87.9% to 89.9% of total identified FAs. The C16:0 and C18:1 (8-octadecenoic acid) represented the majority of LCFA. PCA showed three significantly different groups. Colour was significantly different (p < 0.05). L* whiteness/brightness range was 43.2 to 70.6, a* greenness/redness range was −5.6 to +2 respectively, b* yellowness range was +1.6 to +5.9. Preliminary sensory evaluation results showed consumers (n = 23) could identify differences in milk colour and flavour (p < 0.05). Fatty acid profiles and sensory characteristics were significantly different between whole milk samples produced from different WA processors. The present study provides valuable information of FA composition in commercial milk for potentially developing alternative dietary fat sources and contributing to human health.

Ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS/MS) enables simultaneous identification and quantification of beta-casomorphine 5 (β-CM5) and beta-casomorphin 7 (β-CM7) at the level of ng/mL in milk. This analytical technique uses stable isotope-labeled beta-casomorphin 5 (β-CM5-d10) and beta-casomorphin 7 (β-CM7-d10) to achieve accurate quantitation of target peptides. In addition, solid-phase extraction (SPE) can be used for concentration and purification of milk extracts to improve the limits of detection and quantitation of the method.

Ginsenosides are saponins found in plants of panax genus. Despite having a wide range of health benefits, they cannot optimally reach their target tissues and organs due to their low intestinal absorption. However, reduction of their sugar moieties can produce more absorbable and bioactive compounds. Even though they are known as a good source of glycosidase, edible and medicinal mushrooms are less investigated for their capability to hydrolyse ginsenosides. An enzyme from Cordyceps militaris was used to convert ginsenosides from Panax notoginseng roots. Response surface methodology was used to study the effect of temperature (30 – 60 °C), pH (6 – 7), time (30–80 h) and enzyme concentration (0.5 – 1%), on minor ginsenoside production and optimum conditions for maximum ginsenoside hydrolysis. Regression analysis was used to develop a second-degree polynomial model for the production of minor ginsenosides. Statistical significance of the model was evidenced by coefficient of determination (R2 = 95.15%) and (P value = 0.000). Minor ginsenosides production was affected by enzyme concentration, temperature and time respectively in order of magnitude. The effect of pH was found insignificant. Maximal minor ginsenosides were found at 0.86% enzyme concentration, 42.88 °C, 62.63 h and pH 6.62. A significant difference between hydrolysates from different treatments was observed for DPPH scavenging activity and antimicrobial activity. Hydrolysates have shown a strong cytotoxic activity against (SK-LU-1) and (MCF-7) cell lines. The model developed for Panax notoginseng hydrolysis by C. militaris derived glycosidase can potentially be used for producing minor ginsenosides with improved bioactivities for use in the production of food and medicines.

This study assessed the impact of heat treatment on beta-casomorphin 5 (β-CM5) and beta-casomorphin 7 (β-CM7) after in-vitro gastrointestinal digestion of milk representing beta-casein (β-CN) A1A1, A2A2 and A2I phenotype. After heat treatment at 73 °C/20 s, 85 °C/5 min and 121 °C/12 min, milk samples were subjected to in-vitro gastrointestinal digestion. β-CM5/7 were analysed using ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and further confirmed using ultra high-performance liquid chromatography-high resolution accurate mass Orbitrap™ mass spectrometry (UHPL-HRMS). β-CM5 was not released after in-vitro gastrointestinal digestion of all heated milk. Similarly, β-CM7 was not released in all milk with β-CN A2A2 phenotype. However, this peptide level ranged from 127.25 to 198.10 ng/mL (4.94–7.70 ng/mg protein) in heated milk with β-CN A1A1 phenotype, whereas it was released at much lower levels ranging from 19.35 to 24.50 ng/mL (0.71–0.91 ng/mg protein) in heated milk with β-CN A2I phenotype.