基于电子舌的氯吡脲对草莓风味影响的研究

在草莓“甜查理”盛花后一周,喷施清水及4个浓度（2.5、5.0、10、20 mg/L）的氯吡脲,检测由此产生的草莓果实可溶性固形物、总酸、游离氨基酸、单宁等风味营养品质含量,电子舌分析技术检测酸、甜、苦、鲜、咸、涩味、苦味回味、涩味回味等味觉指标,评价氯吡脲的使用及浓度水平对草莓风味营养品质和滋味的影响,并分析电子舌在检测氯吡脲对草莓滋味影响方面运用的优势。结果表明：氯吡脲能够提高草莓果实的可溶性固形物的含量,降低总酸含量,提高固酸比值,降低游离氨基酸种类和游离氨基酸总量;低浓度（2.5、5.0 mg/L）的氯吡脲处理能降低草莓单宁含量,而高浓度（10、20 mg/L）处理会使单宁含量显著升高;电子舌味觉分析结果表明低浓度氯吡脲处理可使草莓甜味增加,酸味降低,但是咸味和鲜味及与其高度相关（相关系数均为0.99）的苦味也相应降低;游离氨基酸总量与鲜味值、单宁含量与涩味回味值、总酸含量与酸味值、固酸比与甜味值均呈正相关性。低浓度氯吡脲使用对草莓的甜味、酸味等滋味和风味组成具有正面影响,而无论氯吡脲浓度使用高低对咸味和鲜味等滋味和风味组成均有负面影响。     

Flavor Characteristics of Lactic, Malic, Citric, and Acetic Acids at Various pH Levels

The objective of this study was, through the use of free-choice profiling, to determine flavor characteristics of four acids (citric, malic, lactic, acetic) and two acid blends (lactic/acetic 1:1 and 2:1) at three different pH levels (3.5, 4.5, 6.5) and at 0.2% (w/v). Research was conducted to explores flavor differences and similarities among common food acidulants. Generalized Procrustes Analysis was performed on free-choice profiling data, which resulted in three significant principal axes. The first principal axis was characterized by overall intensity and sourness, the second by vinegar and saltiness, and the third by astringency.     

Ready-to-drink protein beverages: Effects of milk protein concentration and type on flavor

This study evaluated the role of protein concentration and milk protein ingredient [serum protein isolate (SPI), micellar casein concentrate (MCC), or milk protein concentrate (MPC)] on sensory properties of vanilla ready-to-drink (RTD) protein beverages. The RTD beverages were manufactured from 5 different liquid milk protein blends: 100% MCC, 100% MPC, 18:82 SPI:MCC, 50:50 SPI:MCC, and 50:50 SPI:MPC, at 2 different protein concentrations: 6.3% and 10.5% (wt/wt) protein (15 or 25 g of protein per 237 mL) with 0.5% (wt/wt) fat and 0.7% (wt/wt) lactose. Dipotassium phosphate, carrageenan, cellulose gum, sucralose, and vanilla flavor were included. Blended beverages were preheated to 60°C, homogenized (20.7 MPa), and cooled to 8°C. The beverages were then preheated to 90°C and ultrapasteurized (141°C, 3 s) by direct steam injection followed by vacuum cooling to 86°C and homogenized again (17.2 MPa first stage, 3.5 MPa second stage). Beverages were cooled to 8°C, filled into sanitized bottles, and stored at 4°C. Initial testing of RTD beverages included proximate analyses and aerobic plate count and coliform count. Volatile sulfur compounds and sensory properties were evaluated through 8-wk storage at 4°C. Astringency and sensory viscosity were higher and vanillin flavor was lower in beverages containing 10.5% protein compared with 6.3% protein, and sulfur/eggy flavor, astringency, and viscosity were higher, and sweet aromatic/vanillin flavor was lower in beverages with higher serum protein as a percentage of true protein within each protein content. Volatile compound analysis of headspace vanillin and sulfur compounds was consistent with sensory results: beverages with 50% serum protein as a percentage of true protein and 10.5% protein had the highest concentrations of sulfur volatiles and lower vanillin compared with other beverages. Sulfur volatiles and vanillin, as well as sulfur/eggy and sweet aromatic/vanillin flavors, decreased in all beverages with storage time. These results will enable manufacturers to select or optimize protein blends to better formulate RTD beverages to provide consumers with a protein beverage with high protein content and desired flavor and functional properties.     

不同颜色大蒜品质分析

以打破休眠期的大蒜为原料,制备白色、绿色和黄色3种颜色大蒜,对其总酚含量、还原糖含量、自由基清除率、风味及味道进行测定,探究不同颜色大蒜的营养价值、抗氧化能力及感官品质的差异。结果表明,不同颜色大蒜的营养价值、抗氧化能力及感官品质存在显著差异。新鲜白色大蒜中含有较多总酚,绿蒜次之,黄蒜中最少。还原糖含量恰恰相反,黄色大蒜含量最高。不同颜色大蒜都具有较好的清除自由基能力,清除自由基能力强弱为新鲜白色大蒜>绿色大蒜>黄色大蒜。风味分析中,氮氧化合物(W5S)和硫化物(W1W)的感应器具有明显响应值变化,且响应值大小排序为黄色大蒜>绿色大蒜>新鲜白色大蒜。而味觉上,咸味、甜味、酸味、苦味上存在明显差异。绿色和黄色大蒜保持较好酸味,同时甜度下降。新鲜白色大蒜可以较好维持咸味和苦味。     

Impact of apple procyanidins on sensory perception in model cider (part 2): Degree of polymerization and interactions with the matrix components

The impact of the degree of polymerization (DP) of procyanidins and its interactions with fructose, acidity and alcohol in a model solution of cider was investigated. Four sensory characteristics (bitterness, astringency, sweetness and sourness) were studied. At 750 mg/L of procyanidins, the DP impacted astringency and bitterness but not sweetness or sourness. The medium DP (tetramer) of apple procyanidins was the most bitter and astringency increased with the DP. The impact of ethanol, fructose and acidity on the four sensory attributes was also examined. These results provide insights into how the components interact to produce the taste of cider.     

EFFECT OF HYDROCOLLOIDS ON APPARENT VISCOSITY AND SENSORY PROPERTIES OF SELECTED BEVERAGES1

The effects were studied of low concentrations of 5 selected hydrocolloids (xanthan, hydroxypropylcellulose, sodium alginate, and carboxymethylcellulose of low and medium viscosity types) on viscosity and sensory properties of 3 commercial beverages: tomato juice, orange drink and soluble coffee. Tomato juice and orange drink were tested at 0° and 22°C, while coffee was tested at 22° and 60°C by 11-14 highly trained judges. Apparent physical viscosity was determined with a Brookfield uiscometer. Due to precipitate formation, it was not possible to test sodium alginate in orange drink nor hydroxypropylcellulose in coffee at 60°C. Without exception, increasing the hydrocolloid concentration significantly depressed (P < 0.001) the flavor and aroma intensities of all beverages a t both test temperatures. Taste effects were specific for the gumlbeverage combinations. In general, gums depressed the sourness and saltiness of tomato juice, the sourness of orange drink and the bitterness of coffee. Both physical and oral viscosities increased with gum concentration and decreased with temperature. Positive synergism was displayed by gums in tomato juice and orange drink. Excellent correlations (r > 0.9) were obtained between sensory and physical viscosities.     

Malolactic fermentation in four varieties of sea buckthorn (Hippophaë rhamnoides L.)

Malolactic fermentation (MLF) used in winemaking was applied to four varieties of sea buckthorn (Hippophaë rhamnoides L.). Sensory properties and chemical components of fermented and unfermented juices were studied in order to see whether the MLF can have an effect on sensory quality of sea buckthorn and if there are differences between varieties. The juices were inoculated with unadapted Oenococcus oeni at a cell density of 10⁹ CFU/mL and the fermentation was performed over 18 h at 28 °C. The fermentation decreased sourness and astringency in the samples, and fruity flavor as well as fermented flavor were increased. However, the ML reaction was different between the varieties. The size of the reaction was not proportional to the initial pH or malic acid content of the juice. Larger the ML reaction, more changes were observed in the sensory properties.     

Effects of replacing buttermilk with yogurt acid whey in ranch dressing

Greek-style yogurt has expanded from 5 to 50% of the US yogurt market in the past decade, accompanied by a corresponding increase in production of its by-product: yogurt acid whey (YAW). Yogurt acid whey qualities (e.g., low pH, mineral content, astringency, and saltiness) present challenges for processing, disposal, and ingredient use. A shelf-stable ranch dressing was formulated by replacing buttermilk in the control with YAW and concentrated YAW (6.3 to 25.2 °Brix). Added salt, gums, and acids were adjusted. The effects of buttermilk substitution on stability were studied on pasteurized samples (8 mo at room temperature). A consumer sensory study (n = 96) was conducted utilizing hedonic and just-about-right scales. Purchase intent and demographic data were also collected. A focus group (n = 7) evaluated the sensorial attributes of the samples after 6 mo. The experiment was performed in triplicate and all instrumental analyses (pH, soluble solids as °Brix, water activity, refraction index, and color) were conducted in triplicate for statistical analysis. Increasing the gum content in YAW samples resulted in equivalent texture liking compared with the control. Matching the control's NaCl concentration resulted in undesirable higher saltiness. The pH of the 18.9 °Brix YAW ranch sample without lactic acid added was under 4.6, with no effect on flavor liking. Increasing concentrations of YAW decreased L* and water activity, and increased the refractive index and hue. The YAW samples presented minimum changes over 8 mo of storage and had better water retention than the control. We conclude that 15 to 17 °Brix YAW is the optimal replacement for buttermilk in a dressing. The formulation of dressings may be accomplished successfully, sustainably, and cost effectively, with minor processing adjustment, by substituting buttermilk with YAW.     

Sensory, chemical and gas chromatographic evaluation of five raspberry cultivars

Five raspberry cultivars, ‘Chilcotin’, ‘Chilliwack’, ‘Meeker’, ‘Skeena’ and ‘Tulameen’, were evaluated for sensory attributes, and chemical and flavor volatile compounds. ‘Chilliwack’ and ‘Tulameen’ received high ratings in sweetness and overall impression with high soluble solids, total sugars and sugar:acid ratio. ‘Chilcotin’ rated low in overall impression and sweetness, and high in sourness and astringency, with low soluble solids, sugar:acid ratio and total sugars, and high titratable acidity. Principal factor analysis (PFA) of the sensory results separated the cultivars based on desirable (appearance, color, texture, aroma and sweetness) and less desirable (sourness, bitterness, astringency and off-flavor) attributes. Twenty-eight volatile compounds were analyzed by dynamic headspace and 18 identified by gas chromatography-mass spectrometry (GC-MS), most of which were terpenes which included -pinene, sabinene, γ-terpinene, - and β-ionone and caryophyllene. Volatile compounds varied among cultivars, with benzaldehyde (11·1–31·8%), -pinene (4·0–11·5%), ethyl heptanoate (6·9–15·2%), β-myrcene (13·2–19·6%) and γ-terpinene (12·2–20·0%) as the predominant volatiles. Correlation analysis established no relationships between sensory and chemical data with volatile compounds.     

Impact of apple procyanidins on sensory perception in model cider (part 1): Polymerisation degree and concentration

The impact of the degree of polymerization and of the concentration of procyanidins in a model solution of French cider was investigated. Four purified fractions of procyanidins at three concentrations were added in a solution containing water, ethanol, fructose and malic acid. The four studied sensory characteristics (bitterness, astringency, sweetness and sourness) were modified according to the concentration of procyanidins. The degree of polymerization (DP) of procyanidins influenced only bitterness and astringency but this impact was not the same for all concentrations. Despite the fact that pH, fructose and malic acid concentrations were the same in all samples, the perception of sweetness and sourness were modified according to the concentration of procyanidins.     

Bitterness and Immature Flavor in Grapefruit:Analyses and Improvement of Quality

Coumarin concentration was very high in early grapefruit juice had an undesirable “immature” or “greenish” flavor. Thirteen Coumarins and psoralens were isolated and identified from such juices. Specific compounds added to mature Duncan juice increases in astringency, sourness and bitterness. About 35% of naringenin-7-beta-rutinoside and 80% of the hesperidin were along with most suspended pulp when such juices were centrifuged. TLC analysis of insoluble solids indicated over 50% of five coumarins and about 25% of five other compounds were removed. Overall quality of grapefruit juice was improved following centrifugation.     

GRAPE JUICE AS AN EXTENDER AND SWEETENER FOR BLUEBERRY DRINKS1

Blueberry juice has a strong flavor and low sugar content, but does not make an affordable, palatable drink unless mixed with water or another juice. This study investigated characteristics of blueberry juice blended with Concord, Reliance, Sunbelt, and Venus grape juices, and Thompson Seedless concentrate (TSC), The blends were evaluated by a trained sensory panel for the attributes of blueberry flavor, color, and aroma, and for astringency, body, and sweetness. Intensity of blueberry-related sensory attributes increased with increased concentration of blueberry juice for all two-way juice beverage blends. Blends sweetened with high fructose corn syrup (HFCS) as opposed to TSC were perceived as significantly different in triangle testing. In three-way blends of blueberry, Concord, and water, replacing HFCS with TSC as a sweetener, and increasing the percentage of blueberry and Concord juice increased intensity ratings for blueberry aroma, and the effects were additive. For the attributes of body, color, flavor, and sweetness, changing sweeteners had no effect, but increasing the percentage of blueberry and Concord grape juice increased the intensity ratings for these characteristics.     

Sensory quality and compositional characteristics of blackcurrant juices produced by different processes

Effects of enzymatic and non-enzymatic juice pressing on key orosensory and chemical quality factors of blackcurrant juices were studied in laboratory scale using berries of five different cultivars (Mortti, Mikael, Marski, Ola and Breed15). Enzymatic processing increased the juice yield by 10–22% and the content of various phenolic compounds in juice by 4–10-fold as compared to the non-enzymatic process. Higher intensity of the mouth-drying astringency of the enzyme-aided juice was the most significant orosensory difference between the processes. Juices of different blackcurrant cultivars varied in sweetness, sourness and bitterness. The most intensive sensory attributes of the juices were sourness and puckering astringency regardless of processing method. They correlated positively with each other and were contributed by acid content and pH. In enzyme-aided juices, the contents of flavonol glycosides and hydroxycinnamic acids were associated with mouth-drying astringency, and sugar/acid ratio correlated with sweetness. These correlations were less clear in non-enzyme juices possibly due to lower content of phenolic compounds and the high content of pectin.     

Factors regulating astringency of whey protein beverages

A rapidly growing area of whey protein use is in beverages. There are 2 types of whey protein-containing beverages: those at neutral pH and those at low pH. Astringency is very pronounced at low pH. Astringency is thought to be caused by compounds in foods that bind with and precipitate salivary proteins; however, the mechanism of astringency of whey proteins is not understood. The effect of viscosity and pH on the astringency of a model beverage containing whey protein isolate was investigated. Trained sensory panelists (n = 8) evaluated the viscosity and pH effects on astringency and basic tastes of whey protein beverages containing 6% wt/vol protein. Unlike what has been shown for alum and polyphenols, increasing viscosity (1.6 to 7.7 mPa·s) did not decrease the perception of astringency. In contrast, the pH of the whey protein solution had a major effect on astringency. A pH 6.8 whey protein beverage had a maximum astringency intensity of 1.2 (15-point scale), whereas that of a pH 3.4 beverage was 8.8 (15-point scale). Astringency decreased between pH 3.4 and 2.6, coinciding with an increase in sourness. Decreases in astringency corresponded to decreases in protein aggregation as observed by turbidity. We propose that astringency is related to interactions between positively charged whey proteins and negatively charged saliva proteins. As the pH decreased between 3.4 and 2.6, the negative charge on the saliva proteins decreased, causing the interactions with whey proteins to decrease.     

Maturity and ripening effects on chemical and sensory properties of apple juice

The effects of harvest maturity and ripening on the chemical composition and sensory characteristics of ‘McIntosh’ and ‘Spartan’ apple juice were evaluated. Juice was extracted from fruit harvested at seven weekly intervals beginning 3–4 weeks before commercial harvest and from fruit held in air storage (1°C) for 1 to 3 months. Internal ethylene concentration and starch index were used as maturity indices. Principal component analysis of juice data (pH. titratable acidity, organic acids, soluble solids, sugars, phenols, turbidity, and Hunterlab colour) showed a distinctive maturity effect on the characteristics of juice extracted from fruit immediately after harvest or after storage. Triangle testing showed aroma and flavour differences in both ‘McIntosh’ and ‘Spartan’ to be first discernable when ethylene was first detected (internal ethylene concentration ≥ 0.1 μl litre^?1) and starch hydrolysis evident (starch index 3.0–5.0 for ‘McIntosh’, 1.5–3.0 for ‘Spartan’), or after 2–3 months of air storage. Sensory profiling of fruity aroma, total aroma, fruit flavour by mouth, sweetness, and sourness in the juices showed increased fruitiness and sweetness and decreased sourness with advancing maturity.     

Effects of smoking and marination on the sensory characteristics of cold-cut chicken breast filets: A pilot study

This study aimed to determine individual and combined effects of smoking and marination on the sensory characteristics of boneless, skinless chicken breast meat. Four types of cooked, cold-cut chicken breast meat, i.e., marinated cooked, marinated smoked, and controls of non-marinated cooked and non-marinated smoked chicken, were evaluated for 28 sensory characteristics. Marination significantly increased saltiness, sweetness, roasted flavor, smoked flavor, and moistness of the cold-cut chicken breast meat. In addition, smoking significantly enhanced the saltiness, bitterness, roasted flavor, smoked flavor, and moistness of mass. Interestingly, a combination of smoking and marination processes resulted in a synergistic increase in the perceived moistness of mass compared to their individual treatments. In conclusion, this study demonstrates individual and combined influences of smoking and marination on the sensory characteristics of cold-cut chicken breast meat.