微波泡沫干燥条件对树莓果浆干燥特性影响

为了研究微波泡沫干燥树莓果浆传热传质特性,以树莓为原料,采用中心组合实验设计方法,研究干燥条件对物料温度、含水率以及介电特性的影响规律,分析微波泡沫干燥过程中传热传质过程。结果表明:微波泡沫干燥树莓果浆过程中,干燥初期,介电常数与介电损耗因子均增大,使得物料吸收的微波能增大,果浆温度由室温上升至70℃,含水率无明显变化;干燥中期,介电常数与介电损耗因子先增大后减小,因此物料吸收的微波能呈先增大后减小趋势,果浆含水率由90%降至40%,温度变化不明显;干燥后期,介电常数与介电损耗因子均减小,物料吸收的微波能减少,果浆含水率缓慢降至15%左右,温度继续升高。微波泡沫干燥方法可有效提高高粘度果浆的干燥速度。      

The use of buttermilk as a raw material for cheese production

Buttermilk is dairy by‐product of butter production. The study aimed to analyse the quality properties of commercial buttermilk and its usefulness as a raw material for Quark cheese production. Within the study, 6 kinds of buttermilk were tested and used for cheese production. Evaluation of cheese quality included physico‐chemical, rheological and sensory analyses. Buttermilk properties were varied and corresponded with the diversification of cheese characteristics. Production yield was 17.2–22.7%, water content 68.1–75.8% and pH 4.09–4.43. The texture was diversified; however, all samples had good sensory quality. The research has shown that buttermilk is a good raw material for cheese production.     

Quality of fresh and stored foam mat dried Mandarin powder

Foam mat drying is a lucrative process of mandarin (kinnow) pulp preservation in the form of powder. Foam mat drying of mandarin pulp experiments were carried out at 65, 75 and 85 °C drying air temperatures using carboxy methyl cellulose, milk and egg white as foaming agents at different concentrations levels to get dried mandarin powder. Quality of the reconstituted dried Mandarin pulp‐powder was evaluated for 6 month storage studies at an interval of 2 months for total sugars (%), ascorbic acid (mg 100 mL^?1), total acid (%), pH and microbial load (fungal and bacterial) using standard procedures. It was observed that total sugars, ascorbic acid and total acid were decreased whereas pH was slightly higher than the fresh pulp. There was minor bacterial growth noticed in all the treatments, which is within the permissible limit, furthermore no fungal growth was noticed during storage period.     

Volatile fraction and sensory characteristics of Manchego cheese. 1. Comparison of raw and pasteurized milk cheese

Manchego cheese can be manufactured from raw or pasteurized ewes' milk. An automatic purge and trap apparatus, coupled to a GC-MS was used to isolate. identify and compare the relative amounts of the volatile components of raw and pasteurized Manchego cheese during ripening. The majority of volatile compounds were more abundant in raw milk (RM) cheeses than in pasteurized milk (PM) cheeses. Alcohols and esters predominated in the profile of RM Manchego cheese, while methyl-ketones and 2,3-butanedione were quantitatively important in PM cheeses. Branched chain alcohols were much more abundant in RM cheeses. The discriminant analysis separated 100% samples into RM or PM cheeses by using only 16 volatile compounds. Aroma intensity was correlated with esters, branched chain aldehydes and branched chain alcohols in RM cheeses, and with esters, branched chain aldehydes, 2-methyl ketones and 2-alkanols in PM cheeses. Diacetyl was positively correlated with the aroma attribute 'toasted' and negatively correlated with aroma quality in PM cheeses.     

Physicochemical, microbiological and sensory changes during ripening and storage of Xinotyri, a traditional Greek cheese from raw goat's milk

Physicochemical, microbiological and sensory characteristics, evolution of lipolysis monitored by measuring acid degree value (ADV) and the main mineral elements were studied during ripening and storage of artisanal Xinotyri cheese from raw goat's milk. Cheeses were characterized by a high content in total solids (TS; 83%) and fat (59% of TS), and very low pH (4.0), water activity (0.87) and moisture (17%). Protein and salt contents at the end of storage were 31% and 2.8%, respectively. Lipolysis increased, while variations in mineral (Ca, P, Mg and Zn) content were found during ripening and storage. Cheeses were free of Salmonella and Listeria in 25 g, while enterobacteria, pseudomonads, and coagulase-positive staphylococci were < 100 cfu/g. Mesophilic lactic acid bacteria increased above 8 log cfu/g by day 6, but declined by 2–3 logs in the ripened cheese (45 days) and by 3–4 logs during cheese storage at 4°C for up to 180 days.     

干燥方法对山草莓生食的理化和感官特性的影响

采用热风干燥和冷冻干燥的方法制作山草莓生食,通过对山草莓生食的营养和生理活性成分及感官评定的分析,寻求制作山草莓(Rubus coreanus)生食的最佳干燥方法。结果表明:在冷冻干燥和低温热风干燥(50、60℃)条件下制得的山草莓生食的营养成分和pH值均无显著性差异;色度中冷冻干燥的a*值和L*值最高,而b*值最低;通过冷冻干燥法制得的山草莓生食中酚类化合物和Vc的含量均较高,分别为0.19%和6.87mg/100mL,感官特性也最佳。因此,从营养成分、生理活性成分以及感官评定的结果来看,冷冻干燥方法更适合于制作山草莓生食。     

Free fatty acid composition of regionally-produced Spanish goat cheese and relationship with sensory characteristics

A study was made of free fatty acid composition and sensory characteristics (odour and taste) in regionally-produced Spanish goat cheeses. The most abundant FFAs were oleic, palmitic, stearic, capric and myristic acid which together accounted for roughly 85% of total FFAs. These cheeses generally underwent a lower degree of lipolysis than did other goat cheeses. Panellists judged the cheeses as having considerable odour and flavour intensity. However, both total FFA content and sensory attributes varied considerably among cheeses due, in all likelihood, to differences in ripening time and to production by different manufacturers. Principal component analysis generated three principal components (PC) that accounted for 70% of total variance; the variables that best correlated with them were long-chain and medium-chain free fatty acids (PC1), brine odour, bitterness and goat milk odour (PC2) and short-chain free fatty acids (PC3).