The effect of thermal pasteurization, freeze-drying, and gamma irradiation on donor human milk

New alternatives to holder pasteurization in processing donor milk in human milk banks

Infectious and toxicological risks are the main potential hazards that operators of Human Milk Banks (HMBs) encounter and must eliminate. HMBs are trying to implement procedures that allow to manage and sanitize human milk without altering significantly its nutritional and biologically protective components, obtaining a product characterized by a valid balance between safety and biological quality. The history of human milk processing is linked to the origins of HMBs themselves. And although other forms of sterilization were used originally, pasteurization soon became the recognized most effective means for sanitizing milk: all the milk that arrives at the HMB must be pasteurized. Holder pasteurization (HoP) is the most used methodology, and it is performed using low temperature and long time (+62.5°C for 30 min). With HoP some bioactive milk components are lost to varying degrees, but many other precious bioactive compounds are completely or partially preserved. To improve the quality of human milk processed by HMBs, maintaining in the meantime the same microbiological safety offered by HoP, new technologies are under evaluation. At present, High-Temperature Short-Time pasteurization (HTST) and High-Pressure Processing are the most studied methodologies. HTST is already utilized in some HMBs for daily practical activity and for research purposes. They seem to be superior to HoP for a better preservation of some nutritional and biologically protective components. Freeze-drying or lyophilization may have advantages for room temperature storage and transportation. The aim of this study is to evaluate the advancement regarding the processing of DHM with a literature search from 2019 to 2022. The effects of the new technologies on safety and quality of human milk are presented and discussed. The new technologies should assure microbiological safety of the final product at least at the same level as optimized HoP, with an improved preservation of the nutritional and bioactive components of raw human milk.

Lyophilized (freeze-dried) human milk for preterm infants: a scoping review

Freeze-drying (FD), or lyophilization, is commonly used to preserve foods. FD offers potential to create a human milk-derived human milk fortifier, and an alternative to freeze-storing human milk. However, processing human milk is known to affect its components. This scoping review explores the effect of FD on the; macronutrient, micronutrient, vitamin, bioactive components, microbes and anti-microbial factors in human milk, and studies where lyophilized human milk has been given to newborn infants. 48 articles were identified after full text review. FD human milk reduces the fat globule size and as well as the quantity of enzymes, vitamin C and immunoglobulin. Common serum electrolyte disturbances have been reported when preterm infants' are fed FD human milk however it appears a promising method to avoid exposure of preterm infants' to cows' milk. Due to limited data, further studies exploring the safety and efficacy of FD human milk in preterm infants are needed.

Effect of electron beam irradiation on raw goat milk: microbiological, physicochemical and protein structural analysis

BACKGROUND

Goat milk is considered a nutritionally superior resource, owing to its advantageous nutritional attributes. Nevertheless, it is susceptible to spoilage and the persistence of pathogens. Electron beam irradiation stands as a promising non-thermal processing technique capable of prolonging shelf life with minimal residue and a high degree of automation.

RESULTS

The effects of electron beam irradiation (2, 3, 5, and 7 kGy) on microorganisms, physicochemical properties, and protein structure of goat milk compared with conventional pasteurized goat milk (PGM) was evaluated. It was found that a 2 kGy electron beam irradiation reduces the total microbial count of goat milk by 6-logs, and the irradiated goat milk protein secondary structure showed a significant decrease in ɑ-helix content. Low irradiation doses led to microaggregation and crosslinking. In contrast, high doses (≥ 5 kGy) slightly disrupted the aggregates and decreased the particle size, disrupting the microscopic surface structure of goat milk, verified by scanning electron microscopy and confocal laser scanning microscopy.

CONCLUSION

The irradiation of goat milk with a 2 kGy electron beam may effectively inactivate harmful microorganisms in the milk and maintain/or improve the physicochemical quality and protein structure of goat milk compared to thermal pasteurization. © 2024 Society of Chemical Industry.

Understanding the factors affecting the surface chemical composition of dairy powders: a systematic review

Dairy powder, with abundant chemical components such as protein, fat, and lactose possessing diverse physical and chemical structures, can exhibit a surface composition distinct from its bulk content during the conversion of liquid milk into dry powder. Surface chemical composition is a significant parameter in the dairy industry, as it is directly associated with the techno-functional properties of dairy powder products. The current work provides an overview of the factors influencing the surface composition of dairy powders such as the bulk composition of raw milk (animal source and formulation), liquid dairy processing (homogenization, thermal treatment, and evaporation), the drying process (drying methods as well as operating conditions during the most commonly used spray drying), and storage conditions (temperature, relative humidity, and duration). The underlying mechanisms involved in the variations of particle surface composition include the mechanical properties of emulsion, milk fat globules redistribution caused by mechanical forces, adsorption competition and interactions of ingredients at the water/air interface, dehydration-induced alterations in particle structure, corresponding solid/solutes segregation differentiation during spray drying, and lactose crystallization-induced increase in surface fat during storage. Additionally, future research is suggested to explore the effects of emerging processing technologies on the surface composition modification of dairy powders.

Effects of Drying Methods on the Volatile Compounds of Alliummongolicum Regel

Allium mongolicum Regel (AMR) is a traditional Mongolian food. Various drying methods play an important role in foodstuff flavor. However, the effect of different drying methods on AMR is limited. In this study, freeze drying (FD), vacuum drying (VD), and hot-air drying (HAD) were applied to dry fresh AMR to a moisture content of 8% (wet basis); headspace gas chromatography mass spectrometry was adopted to identify volatile compounds in AMR; and principal component analysis and fingerprint similarity analysis based on the Euclidean distance was used to distinguish the fresh and three dried treatments. In total, 113 peaks were detected and 102 volatile compounds were identified. Drying causes significant changes to the amounts of volatile compounds in AMR, and the drying method plays a key role in determining which volatile compounds appear. Compared to FD, VD and HAD were more appropriate for drying AMR because the volatile compounds after VD and HAD were closer to those of fresh AMR. These findings can provide a scientific basis to help to preserve future seasonal functional food and aid in Mongolian medicine production.

Improvement in the physicochemical characteristics of biochar derived from solid digestate of food waste with different moisture contents

The management of digestate from food waste (DFW) has become a worldwide challenge. Pyrolysis is a promising technology to generate biochar from the DFW. However, unlike other biomass, DFW usually has high salt and moisture content, which affects the properties of biochar generated from pyrolysis. The characteristics of biochar derived from DFW with different MCs (5%, 20%, 40%, and 60%) were investigated in the present study. It was found that more micropore and mesopore structures were generated in the biochar with the increase of MC from 5% to 60%, resulting in the Brunauer-Emmett-Teller surface area of the biochar increased from 89.23 m² g^-1 to 117.75 m² g^-1. The MC could also promote the variation of oxygen-containing functional groups and the generation of amorphous carbon structures, which are beneficial for the adsorption property of the biochar. Pyrolysis could stabilize the metals in the biochar, while MC has little effect on the metal speciations. These results provide fundamental information on the impact of MC on the properties of biochar derived from DFW and are important for the optimization of the pre-drying process.