Improvements in makkhan (traditional Indian cultured butter) production: a review

Valorization of Sour Buttermilk (A Potential Waste Stream): Conversion to Powder Employing Reverse Osmosis and Spray Drying

Reverse osmosis (RO) is known for the economic dewatering of dairy streams without any change in phase. At the household level, surplus milk is fermented and churned to obtain butter, which is subsequently heated to obtain clarified milk fat (ghee). The production of 1 kg ghee generates 15-20 kg sour buttermilk (SBM) as a by-product that is mostly drained. This causes a loss of milk solids and environmental pollution. The processing, preservation and valorization of SBM are quite challenging because of its low total solids (TS) and pH, poor heat stability and limited shelf life. This investigation aimed to transform SBM into a novel dried dairy ingredient. SBM was thermized, filtered, defatted and concentrated at 35 ± 1 °C, employing RO up to 3.62× (12.86%). The RO concentrate was subsequently converted into sour buttermilk powder (SBMP) by employing spray drying. SBMP was further characterized for its physicochemical, reconstitution and functional properties; rheological and morphological characteristics; and amino acid and fatty acid profiling, along with FTIR and XRD spectra. SBMP was "instant soluble-3 s" and exhibited excellent emulsion stability (80.70%), water binding capacity (4.34 g/g of protein), flowability (28.36°) and antioxidant properties. In nutshell, a process was developed for the valorization of sour buttermilk to a novel dairy ingredient by employing reverse osmosis and a spray-drying process.

Recent innovations in functionality and shelf life enhancement of ghee, clarified butter fat

Ghee (clarified butter fat) is a well relished traditional fat rich dairy product. Ghee preparation involves concentration of milk fat using of different techniques, followed by heat treated at 110-120 °C for 10-20 min. During this process, moisture evaporates from the system with simultaneous changes in protein, lactose, fat and minerals. Interaction among these thermally altered species results into the development of characteristic 'ghee' flavor. But, the presence of unsaturated free fatty acids makes it highly susceptible to oxidative spoilage. Efforts have been made to increase the shelf life and functionality of ghee by adding many functional ingredients and natural antioxidants from different sources. This review deals with the different process employed for ghee preparation and the attempts made in the past two decades years to increase the functionality and shelf life of ghee. Also, the changes taking place during ghee preparation and flavour generation has been discussed in this review.

Microbial diversity of milk ghee in southern Gansu and its effect on the formation of ghee flavor compounds

Ghee is a traditional Tibetan dairy product with high-fat content, low yield, plasticity, caseation, and rich nutrition. In this study, we analyzed the diversity of microbial communities in yak milk and ghee samples at high and low altitudes, especially the Lactobacillus genus, and further used metabolomic techniques to compare the differences in metabolites in yak ghee at different altitudes. The results showed that the increase in altitude had a significant and generally inhibitory effect on the microbial community diversity in milk ghee, and yak milk at high altitude was abundant in nutrients, which could antagonize the negative impact of increased altitude. Using non-targeted metabolomics, we infer the composition of flavor compounds in ghee: nine kinds of carboxylic acids, 11 kinds of esters, six kinds of ketones, two kinds of alcohols, and four kinds of alkene compounds, among which the key flavor compounds are dl-2-(acetylamino)-3-phenylephrine acid, 1-(4-methoxyphenyl)-2-propanone, sebacic acid, Lysope 18:1, and uracil 1-beta-d-arabinofuranoside. These flavor substances are found in Lactococcus, Lactobacillus, and Streptococcus. With the participation of Lactobacillus, it is synthesized through biosynthesis of alkaloids derived from ornithine, lysine, and nicotine acid and glyoxylate and decarboxylate metabolism, among which Lactococcus plays a key role. In this study, a variety of lactic acid bacteria related to ghee fermentation were screened out, revealing the composition of volatile flavor compounds in Gannan yak milk ghee in the Qinghai-Tibet Plateau and providing a reference for further key volatile flavor compounds and the formation mechanism of flavor compounds.