How long could you wait to brew espresso after grinding? Ask a barista, any barista, and I suspect their answer is immediately or within a few minutes. The common knowledge on coffee grounds freshness is that after 30 minutes or so, coffee grounds go stale. Even if stored, the common knowledge is that coffee grounds still go stale (the length of freshness is not well defined). Is that always true?

磨碎后您要等多久才能煮浓咖啡？ 问一个咖啡师，任何咖啡师，我怀疑他们的回答是立即或在几分钟之内。 关于咖啡渣新鲜度的常识是，大约30分钟后，咖啡渣变陈旧。 即使已存储，通常的知识是咖啡渣仍然过时(新鲜度的长度定义不清)。 总是这样吗？

My experience with the staccato shot has led me to believe that the common thinking on coffee grounds freshness is not correct. I have looked for supporting data, and there is not much, probably because it seems so obvious. So I will share my experience and my data which suggests that if stored in an airtight container, coffee grounds can be used for at least a few days without losing flavor. The past few months, I’ve been storing my the refrigerator for my spicy shots, but I have also looked back at coffee grounds before I refrigerated them regularly.

我使用断断续续拍摄的经验使我相信，关于咖啡渣新鲜度的一般想法是不正确的。 我一直在寻找支持数据，但数量不多，可能是因为它看起来如此明显。 因此，我将分享我的经验和数据，这些数据和建议表明，如果将咖啡渣保存在密闭的容器中，则至少可以使用几天，而不会失去风味。 在过去的几个月中，我一直在存放冰箱以存放辛辣的食物，但是在我定期对咖啡渣进行冷藏之前，我也回过头来。

以往的经验 (Previous Experience)

For awhile, I was grinding fresh, but that changed when I started to develop the staccato espresso shot. Grinding and sifting for every shot was tedious, so I would grind enough coffee for a few shots, and I would sift and store the coffee in air tight containers.

有一段时间，我一直在磨新鲜，但是当我开始制作断断续续的意式特浓咖啡时，情况发生了变化。 每次研磨和筛分都很繁琐，因此我要研磨足够的咖啡以进行几次注射，然后将咖啡筛分并储存在密封的容器中。

I found such a benefit to the containers that I would grind coffee and store it in them even if I wasn’t going to sift it. To make my process more efficient, I would grind in the morning, and an hour later, I would sift the grounds on my way to work. The time between grind and brew started extending.

我发现这种容器有很大的好处，即使我不想筛分，我也可以将咖啡研磨并储存在容器中。 为了使我的过程更有效率，我会在早上磨碎，一个小时后，我会筛选上班方式。 研磨和冲泡之间的时间开始延长。

I also am lazy when it comes to certain things, and I have on occasion left grinds in sealed containers for multiple days. I didn’t notice much of a degradation in taste.

当涉及到某些事情时，我也很懒惰，有时我会在密封的容器中放多个研磨物。 我没有注意到味道的降低。

数据采集 (Data Collection)

I started recording grind date and time only when I started recording bean temperature at grind. I was doing experiments with hot and cold beans at grind, and I figured I would keep track of it. I typically would grind four shots at a time, and it would take me 2 to 4 days depending on how much time I had to drink fancy coffee.

我只有在开始记录研磨时的豆温度时才开始记录研磨日期和时间。 我在研磨时对热豆和冷豆进行了实验，我想我会一直跟踪它。 我通常一次打四针，这需要2到4天，具体取决于我要花多少时间喝花式咖啡。

I started looking at that data to see if I could tell me if there was any change in taste or extraction yield. When I didn’t see a change (as seen further down), I did a few longer experiments where I would grind 8 shots worth of coffee to drink over a week. I also went back to previous data and labeled estimated grind dates based on when the grounds were sifted, which I recorded separately.

我开始查看这些数据，看是否可以告诉我口味或提取率是否有变化。 当我没有看到变化时(更进一步)，我进行了一些更长的实验，在一周的时间里，我将研磨8杯咖啡。 我还回到了以前的数据，并根据筛选的时间标记了估计的研磨日期，我分别进行了记录。

Most of these shots were using home roasted beans that were 1 to 1:30 minutes past the first crack. I ground the beans on either a Rok grinder or a Lime grinder, and this data is from shots pulled on a Kim Express. Additionally, if one thinks having a better grinder is more important, I would refer them to this work where I used a blade grinder and a sifter to make a good shot of espresso which suggests a sifter equalizes the field of grinders.

这些镜头中的大多数使用的是经过第一次烘烤1至1:30分钟的家用烤豆。 我在Rok磨豆机或Lime磨豆机上将豆磨碎，这些数据来自在Kim Express上拍摄的照片。 此外，如果有人认为拥有一个更好的研磨机更为重要，那么我会推荐他们去做这项工作，在该工作中，我使用了刀片研磨机和筛分机对意式浓缩咖啡进行了很好的拍摄，这表明筛分机可以使研磨机的领域更加均衡。

绩效指标 (Metrics of Performance)

I used two metrics for evaluating the differences between shots: Final Score and Coffee Extraction.

我使用了两个指标来评估镜头之间的差异： 最终得分和咖啡提取 。

Final score is the average of a scorecard of 7 metrics (Sharp, Rich, Syrup, Sweet, Sour, Bitter, and Aftertaste). These scores were subjective, of course, but they were calibrated to my tastes and helped me improve my shots. There is some variation in the scores. My aim was to be consistent for each metric, but some times the granularity was difficult and affected the final score.

最终分数是7个指标(“锋利”，“丰富”，“糖浆”，“甜”，“酸”，“苦”和“回味”)的记分卡的平均值。 这些分数固然是主观的，但是根据我的口味进行了校准，并帮助我改善了投篮。 分数有所不同。 我的目标是使每个指标保持一致，但有时粒度很困难并且影响最终分数。

Total Dissolved Solids (TDS) is measured using a refractometer, and this number is used to determine the percentage of coffee extracted into the cup in combined with the output weight of the shot and the input weight of the coffee, called Extraction Yield (EY).

使用折光仪测量总溶解固体(TDS)，此数字用于确定提取到杯子中的咖啡的百分比以及小球的输出重量和咖啡的输入重量，称为提取率(EY) 。

数据发现 (Data Findings)

First, looking at the data, I plotted all the data, and I didn’t notice anything. There was definitely variation over the days in taste (Final Score) and EY, but I didn’t see any patterns. I will note that I stored most of these grounds in the refrigerator due to spicy grinding, but I haven’t noticed a taste degradation for grounds stored at room temperature for a day or two.

首先，查看数据，我绘制了所有数据，但没有发现任何东西。 这些天的口味(最终得分)和EY肯定有差异，但是我没有看到任何规律。 我会注意到，由于辛辣研磨 ，我将大部分这些碎屑储存在冰箱中，但是我并没有注意到室温下存放一两天的碎屑的味道会下降。

So I broke it down by roast, and I shorted the time window to 3 days maximum. Again, each roast seemed not to degrade over time. There was variations within the day related to changes in some experiments I was running, but there was not a trend.

因此，我将其分解为烤肉，并将时间窗口缩短至最长3天。 同样，每次烘烤似乎都不会随着时间而降低。 当天发生的变化与我进行的某些实验的变化有关，但没有趋势。

I decided to simply the data. I cut it in half because half of the data had a grind age of less than 1 day and 4 hours. I wanted to do within a day and greater than a day, but it wasn’t an even cut. In this split, there were some differences, but none of the distribution differences were statistically significant.

我决定简单地处理数据。 我将其减少了一半，因为一半的数据的磨合时间少于1天4个小时。 我想在一天之内完成一天以上的工作，但这并不是一成不变的。 在此拆分中，存在一些差异，但所有分布差异均无统计学意义。

I typically would grind enough for four 18g shots, and I wanted to test the grinds over a longer window than previous. I did this with two roasts, and I saw variations, but not trends. The grounds were also stored in the refrigerator which could have contributed to their taste staying fresh.

我通常会打够四个18g的镜头，而且我想在比以前更长的窗口上测试这些镜头。 我进行了两次烧烤，发现变化，但没有趋势。 地面也被存储在冰箱中，这可能有助于保持口感新鲜。

射击时间 (Shot Time)

Shot time also seemed unaffected by grind age. Across the different roasts, the shot time stays pretty consistent, and I didn’t see any trends.

射门时间似乎也不受年龄的影响。 在不同的烘烤中，射击时间保持一致，我没有看到任何趋势。

更多数据 (More Data)

I pulled 359 shots that I have grind time and time of the shot, but with the wealth of data comes the difficulty of trying to make sense of it. So I first plotted it as a scatter plot. No trend is apparent.

我抽出了359张我一直在努力拍摄的照片，但随着大量数据的出现，很难理解它。 因此，我首先将其绘制为散点图。 没有趋势是明显的。

Then, I plotted box plots, and it seems the Final Score or taste improves, but I suspect that improvement is due to improving shot parameters. Also, the distributions are very wide due to the shots being across different roasts and techniques. The is a slight shift in median score, the distribution still stays pretty similar.

然后，我绘制了箱形图，似乎最终得分或味道有所改善，但我怀疑这种改善是由于改善了击球参数。 另外，由于镜头是通过不同的烘烤和技术进行的，因此分布非常广泛。 中位数得分略有变化，分布仍然保持相似。

To extract learning, I normalized (Z-norm) the data by roast. For each roast, I calculated the mean and standard deviation (std). Then, for each metric, per each roast, I made the normalized data by this equation: X_norm = (X – Roast_mean)/Roast_std. If there was a trend due to grind age, it should be clear as a change of the normalized distribution.

为了提取学习内容，我通过烘烤对数据进行了标准化(Z范数)。 对于每个烘烤，我计算了平均值和标准偏差(std)。 然后，对于每个度量标准，每个烘烤，我通过以下等式制作归一化数据：X_norm =(X-Roast_mean)/ Roast_std。 如果存在由于磨削年龄引起的趋势，则应将其归一化为正态分布的变化。

As a scatter plot, there doesn’t seem to be much of a change, so let’s look at box plots below. For Regular shots, Final Score stays about the same while EY increases a little bit.

作为散点图，似乎变化不大，所以让我们看一下下面的箱形图。 对于常规拍摄，最终得分保持不变，而EY有所提高。

For Staccato shots, there is not a trend for any of the metrics. 0 in this case means the mean score while positive is higher than the mean, and negative is lower than th emean.

对于断音拍摄，任何指标都没有趋势。 在这种情况下，0表示平均值，而正数高于平均值，而负数低于平均值。

After a suspicion that grind age didn’t matter as much as has been suggested, I looked through as much data as I could find. I didn’t find any trends positive or negative between grind age and multiple metrics (Final Score (taste), EY, or shot time). The main caveat of ground coffee losing taste is most likely based on leaving it exposed to air for a period of time, but at least from my experience, grind more less often has not had a negative impact to my espresso experience.

在怀疑磨削年龄并不像所建议的那样重要之后，我浏览了尽可能多的数据。 在年龄和多项指标(最终得分(口味)，安永或出手时间)之间，我没有发现任何积极或消极的趋势。 磨碎咖啡失味的主要警告很可能是由于将其暴露于空气中一段时间​​，但至少从我的经验来看，减少磨碎次数对我的浓缩咖啡体验没有负面影响。

If you like, follow me on Twitter and YouTube where I post videos of espresso shots on different machines and espresso related stuff. You can also find me on LinkedIn.

如果您愿意，请在Twitter和YouTube上关注我，在这里我会在不同的机器上发布浓缩咖啡的视频以及与浓缩咖啡相关的内容。 您也可以在LinkedIn上找到我。

我的进一步阅读： (Further readings of mine:)

Deconstructed Coffee: Split Roasting, Grinding, and Layering for Better Espresso

解构后的咖啡：焙炒，研磨和分层，以获得更浓的意式浓缩咖啡

Pre-infusion for Espresso: Visual Cues for Better Espresso

特浓咖啡的预输注：视觉提示可提供更好的特浓咖啡

The Shape of Coffee

咖啡的形状

To Stir or To Swirl: Better Espresso Experience

搅拌或旋流：更好的意式浓缩咖啡体验

Spicy Espresso: Grind Hot, Tamp Cold for Better Coffee

香浓意式特浓咖啡：磨碎热，捣碎冷可制得更好的咖啡

Staccato Espresso: Leveling Up Espresso

Staccato意式浓缩咖啡：升级意式浓缩咖啡

Improving Espresso with Paper Filters

使用滤纸器改善意式浓缩咖啡

Coffee Solubility in Espresso: An Initial Study

浓咖啡中的咖啡溶解度：初步研究

Staccato Tamping: Improving Espresso without a Sifter

Staccato捣固：无需筛分器即可提高浓咖啡

Espresso Simulation: First Steps in Computer Models

浓缩咖啡模拟：计算机模型的第一步

Pressure Pulsing for Better Espresso

压力脉冲使咖啡更浓

Coffee Data Sheet

咖啡数据表

Artisan coffee is overprice

工匠咖啡价格过高

The Tale of the Stolen Espresso Machine

被盗咖啡机的故事

Espresso filter analysis

浓缩咖啡过滤器分析

Portable Espresso: A Guide

便携式意式浓缩咖啡：指南

Kruve Sifter: An Analysis

Kruve Sifter：分析