Condensed milk storage and evaporation affect the flavor of nonfat dry milk

Abstract

Unit operations in nonfat dry milk (NFDM) manufacture influence sensory properties, and consequently, its use and acceptance in ingredient applications. Condensed skim milk may be stored at refrigeration temperatures for extended periods before spray drying due to shipping or lack of drying capacity. Currently, NFDM processors have 2 options for milk concentration up to 30% solids: evaporation (E) or reverse osmosis (RO). The objective of this study was to determine the effect of condensed milk storage and milk concentration method (E vs. RO) on the flavor of NFDM and investigate mechanisms behind flavor differences. For experiment 1, skim milk was pasteurized and concentrated to 30% solids by E or RO and then either stored for 24h at 4°C or concentrated to 50% solids by E and spray dried immediately. To investigate mechanisms behind the results from experiment 1, experiment 2 was constructed. In experiment 2, pasteurized skim milk was subjected to 1 of 4 treatments: control (no E), heated in the evaporator without vacuum, E concentration to 30% solids, or E concentration to 40% solids. The milks were then diluted to the same solids content and evaluated. Volatile compounds were also measured during concentration in the vapor separator of the evaporator. Sensory properties were evaluated by descriptive sensory analysis and instrumental volatile compound analysis was conducted to evaluate volatile compounds. Interaction effects between storage and method of concentration were investigated. In experiment 1, E decreased sweet aromatic flavor and many characteristic milk flavor compounds and increased cardboard and cooked flavors in NFDM compared with RO. Liquid storage increased cardboard flavor and hexanal and octanal and decreased sweet aromatic flavors and vanillin concentration. Results from experiment 2 indicated that the characteristic milk flavors and their associated volatile compounds were removed by the vapor separator in the evaporator due to the heat and vacuum applied during concentration. These results demonstrate that off-flavors are significantly reduced when RO is used in place of E and storage of condensed milk is avoided.

Correlating Volatile Lipid Oxidation Compounds with Consumer Sensory Data in Dairy Based Powders during Storage

“…Li et al [42] reported higher levels of octanal and 3-octen-2-one in concentrated milk and milk powders than in raw and heated milk, suggesting that these compounds are likely thermally induced LO products. Park and Drake [43] also reported increases in octanal in liquid condensed milk after 24 h storage, indicative of LO. However, in the present study, the levels of octanal fluctuated throughout storage in the IMF samples, and the lowest levels were observed in ACC samples (142 ppm ± 5.32).…”

Production of a New Plant-Based Milk from Adenanthera pavonina Seed and Evaluation of Its Nutritional and Health Benefits

“…These also validate the nutritional status of the pro-milk extracts from A. pavonina seeds (Table 2 ). Further, condensation or concentration of the pro-milk extracts with the aid of appropriate technique (such as freeze-drying) during production may be required to maximize the health benefits to consumers and to meet up with the amount declared by the previously fortified commercialized plant milk indicated in Table 2 ( 57 – 61 ).…”

Optimization of goat milk vacuum-assisted block freeze concentration using response surface methodology and NaCl addition influence

“…The variation of independent factors values was obtained by preliminary tests. Based on Park and Drake (2016) and Sharma, Patel, and Patel (2016) were done a preliminary test with this pressure value equal to 74.5 kPa and between 14.6-8.0 kPa, respectively. However, the separation of the concentrated from the ice fraction was observed when the vacuum pump reached 70 kPa until 10 kPa.…”