Analysis of Volatile Organic Compounds in Milk during Heat Treatment Based on E-Nose, E-Tongue and HS-SPME-GC-MS

Potential of beef tallow/palm oil blend as Chongqing hotpot oil from a physicochemical and flavor perspective

Beef tallow is an important raw material in Chongqing hotpot seasoning but raises great concern on health due to the cholesterol issue. Herein, palm oil was expected to replace beef tallow at weight ratios of 2:1, 1:1, and 1:2 without reducing hotpot flavor. The blending of palm oil to beef tallow effectively decreased cholesterol content to 33.20 mg 100 g-1, as well as the level of saturated fatty acids to 50 % in hotpot oil. The fading in brightness and yellowness of oil models occurred owing to heat treatment. The blending oil at 2:1 showed similar hardness, melting and crystallization behaviors to beef tallow, probably due to the similar fat crystal network. The volatile compounds of hotpot seasoning made from the oil were closer to that from neat beef tallow. These findings may provide a new strategy to develop healthier and tastier base oil for the production of Chongqing hotpot seasoning.

Chemically modified filter paper with Jaman fruit extract for visual sensing of milk freshness

Developing a non-toxic, cost-effective, and user-friendly indicator for detecting milk freshness and spoilage, with potential applications in smart packaging, presents a significant challenge. In this study, we extracted natural anthocyanins (ACNs) from Jaman (Syzgium cumini) and incorporated it in to filter paper. The presence of ACNs in the extract was confirmed through UPLC-MS/MS analysis. To enhance stability and prevent leaching, the ACNs-loaded filter paper was coated with 1 % chitosan (CH). The sensor strips were thoroughly characterized using FTIR, contact angle measurements, XRD, and FE-SEM. These strips displayed a distinct and quantifiable color change from red to colorless to yellow across different pH levels. Additionally, in real-time milk spoilage detection, the sensor transitioned from light purple to colorless. The strips demonstrated reproducibility and stability, even under high temperatures and extreme pH conditions. These findings suggest that the ACNs-loaded sensor strips hold promise for use as smart packaging materials.

Effect of Whey Protein Changes on Milk Flavor and Sensory Characteristics During Heating

The flavor of dairy products crucially affects consumer purchase preference. Although the flavor and sensory perception of milk can be influenced by heat treatment during processing, the exact mechanism remains unclear. Therefore, this study analyzed the whey protein content and structural changes of milk heated at different time and temperature combinations and evaluated the flavor compounds and sensory characteristics of milk. The results showed that higher temperatures changed the secondary milk whey protein structures and gradually increased α-lactalbumin, β-lactoglobulin, and lactoferrin denaturation in the milk. There were differences in sensory characteristics of milk heated at different time and temperature combinations. The correlation analysis indicated that whey protein denaturation was negatively correlated with 1-octen-3-ol (p < 0.05) and positively associated with hexanal, isovaleric acid, γ-nonalactone, methyl palmitate, and phenol (p < 0.01). The changes in the content and secondary structure of whey proteins affected the interaction between flavor compounds and whey protein, which affected the release of flavor compounds. Consequently, the sensory characteristics of milk were influenced. This study provides a theoretical basis for exploring the interaction between whey proteins and flavor compounds.

κ-Carrageenan masking bitterness perception in surimi gels containing potassium chloride-based salt substitutes: Gel properties, oral processing, and sensory evaluation

κ-Carrageenan (CG) was employed to mask the bitterness induced by 50% KCl in surimi gels to achieve salt reduction and gel performance improvement. The combination of KCl and CG (KCl + CG) yielded the increased textural characteristics and water-holding capacity (WHC) of surimi gels and facilitated the transition of free water to immobilized water. In addition, the KCl + CG supplement increased the turbidity and particle size of myofibrillar protein (MP) sols but decreased the surface hydrophobicity in a dose-dependent manner. The hydrophobic interactions and disulfide bonds played crucial roles in maintaining the stability of MP gels. The specific binding of potassium ions to the sulfate groups of CG limited the release and diffusion of potassium ions from the surimi gels during oral processing, effectively masking the bitterness perception and maintaining the saltiness perception. This study provides a promising strategy to reduce the utilization of sodium salt in surimi products.

Effects of Broth pH and Chilling Storage on the Changes in Volatile Profiles of Boiled Chicken Flesh

This study investigated the changes in volatile compounds in chicken flesh after boiling at various pHs (6.0-9.0) and after chilling storage (4.0±1.0°C) for 7 d. The volatile compounds were assessed qualitatively and quantitatively by using a headspace gas chromatography-mass spectrometry analysis. Twenty-one volatile compounds were discovered and categorized as amine, aldehyde, alcohol, ketone, acid, and furan. One type of amine, (2-aziridinylethyl) amine, was the most prevalent volatile component, followed by aldehyde, ketone, aldehyde, acid, ester, and furan. The results showed that the quantity and quality of the volatile compounds were influenced by a pH of the boiling medium. Additionally, the types and volatile profiles of the chicken were altered during chilling. In particular, in the chicken that was boiled at a pH of 8.0, the hexanal (an aldehyde) content increased the most after 7 d of chilling. Moreover, various alcohols formed after the 7 d of chilling of the chicken that was boiled at pHs of 8.0 and 9.0. Because of the oxidation and degradation of fat and proteins, the most altering volatile compounds were the reducing amines and the increasing aldehydes.

Z, Cai X, Zhao X, Jiang Y, Miao B. Quality Assessment of Loquat under Different Preservation Methods Based on Physicochemical Indicators, GC–MS and Intelligent Senses

To explore the effects of different preservation methods on the quality of loquat after fresh-keeping treatment, various preservation techniques were employed. These included natural preservation (NP), vacuum freezing preservation (VFP), vacuum at room temperature preservation (VP) and freezing preservation (FP). The quality assessment involved analyzing the effects of these preservation methods using physicochemical indexes, a colorimeter, an electronic nose (E-nose), an electronic tongue (E-tongue) and gas chromatography–mass spectrometry (GC–MS). The results showed minor differences in loquat quality under different preservation methods, with sensory scores ranging from 55 to 78 and ΔE values ranging from 11.92 to 18.59. Significant variations were observed in moisture content (ranging from 53.20 g/100 g to 87.20 g/100 g), calorie content (ranging from 42.55 Kcal/100 g to 87.30 Kcal/100 g), adhesion (ranging from 0.92 to 1.84 mJ) and hardness (ranging from 2.97 to 4.19 N) (p < 0.05). Additionally, the free amino acid content varied from 22.47 mg/g to 65.42 mg/g. GC–MS analysis identified a total of 47 volatile flavor substances in varieties of loquats, including 13 aldehydes, 9 esters, 6 ketones, 2 acids, 3 alcohols, 2 phenols, 3 pyrazines, 1 furan and 8 other substances. The relative content of aldehydes was significantly higher than that of other chemicals. The VFP and FP samples exhibited higher aldehyde content compared to the NP and VP samples. Moreover, Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) revealed 18 marked compounds that could differentiate between 5 loquat species. Analysis using E-nose and E-tongue indicated significant changes in the olfactory and gustatory senses of loquats following preservation. The VFP samples demonstrated the most effective preservation of loquat quality with minimal impact. This study provides some theoretical guidance for the home preservation of loquats.

Non-volatile and volatile compound changes in blueberry juice inoculated with different lactic acid bacteria strains

BACKGROUND

Lactic acid bacteria (LABs) are widely present in foods and affect the flavour of fermented cultures. This study investigates the effects of fermentation with Lactobacillus acidophilus JYLA-16 (La), Lactobacillus plantarum JYLP-375 (Lp), and Lactobacillus rhamnosus JYLR-005 (Lr) on the flavour profile of blueberry juice.

RESULTS

This study showed that all LABs strains preferentially used glucose rather than fructose as the carbon source during fermentation. Lactic acid was the main fermentation product, reaching 7.76 g L-1 in La-fermented blueberry juice, 5.86 g L-1 in Lp-fermented blueberry juice, and 6.41 g L-1 in Lr-fermented blueberry juice. These strains extensively metabolized quinic acid, whereas oxalic acid metabolism was almost unaffected. Sixty-four volatile compounds were identified using gas chromatography-ion mobility spectrometry (GC-IMS). All fermented blueberry juices exhibited decreased aldehyde levels. Furthermore, fermentation with La was dominated by alcohols, Lp was dominated by esters, and Lr was dominated by ketones. Linear discriminant analysis of the electronic nose and principal component analysis of the GC-IMS data effectively differentiated between unfermented and fermented blueberry juices.

CONCLUSION

This study informs LABs selection for producing desirable flavours in fermented blueberry juice and provides a theoretical framework for flavour detection. © 2023 Society of Chemical Industry.

Unraveling volatilomics profiles of milk products from diverse regions in China

To distinguish Chinese milks from different regions, 13 milk samples were gathered from 13 regions of China in this study: Inner Mongolia (IM), Xinjiang (XJ), Hebei (HB), Shanghai (SH), Beijing (BJ), Sichuan (SC), Ningxia (NX), Henan (HN), Tianjin (TJ), Qinghai (QH), Yunnan (YN), Guangxi (GX), and Tibet (XZ). Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) combined with the electronic nose (E-nose) technology, was used to detect and analyze the volatile compounds in these milk samples. The qualitative and quantitative results identified 29 volatile chemicals, and we established a database of flavor profiles for the main milk-producing regions in China. E-nose analysis revealed variations in the odor of milk across different areas. Furthermore, results from partial least squares discriminant analysis (PLS-DA) and odor activity values (OAVs) suggested that seven volatile compounds: decane, 2-heptanone, 2-undecanone, 2-nonanone, 1-hexadecanol, 1-octen-3-ol, and (E)-2-nonenal, could be considered as key flavor compounds in Chinese milk products.